Zinnias are great to grow for summer blooms.

Zinnias are the work horses of the cutting flower garden. They are easy to grow and have a short time from planting to bloom time. They attract bees, butterflies and hummingbirds so are a great addition to a pollinator-attracting garden. I have done some flower show judging at fairs and the first time that I judged zinnias at the Big Fair in Fresno I was amazed at the variety of zinnias as I had only known a few cultivars of Zinnia elegans. There are other species but insufficient room here to describe them all.

Zinnias require rich, well-drained soil in full sun. Zinnias do best when kept evenly moist, and you can feed them with compost or a balanced fertilizer every few weeks for best flower production. For extended bloom, deadhead plants throughout the season or just keep all your vases full. Remove unsightly leaves to prevent the spread of disease and to keep plants looking healthy.

They evolved in the warm climate of Mexico so they are heat and drought tolerant but not frost tolerant and should not be set out before frost time is past. They are best planted after night temperatures reach above 50 degrees F. You can get a head start on the blooming season by starting the seeds indoors or in a greenhouse 4-6 weeks before planting in the garden. Seeds should be planted about 3 inches apart. A sunny windowsill will work and germination takes about 6 days.

Seeds can also be sown directly in the garden; 1⁄2 inch deep with 2- to 3-inch spacing in rows 12 inches apart in well-worked, fertile garden soil in full sun. Gently firm the soil and then keep it evenly moist while awaiting germination. When seedlings become large enough to handle, thin them to 10 to 12 inches apart. In the garden, it is good to provide for air circulation to minimize infection with powdery mildew. Zinnias come in a wide range of colors (except blue) from lime green, red, yellow, pink, orange to white. You can usually purchase a mix of colors or a one-color selection. They also come in a multitude of forms and sizes as described below. Hence they can fit a lot of garden spots from containers to front and back borders.

Petite: ‘Thumbelina’ zinnias generally don’t grow more than 4-6 inches and come in all the colors of the rainbow in a compact, versatile plant that is good in border fronts or containers. ‘Pepito’ and ‘Button Box’ seeds produce dwarf plants that are 10 inches tall. ‘Profusion’ zinnia series is a hybrid of (Zinnia angustifolia x Z. elegans) and it is a low growing choice especially for containers or mass planting. The two-inch flowers are single or semi-double and daisy-formed which cover 12 to 15-inch mounding plants. This All-America Selections award-winning series has cultivars that come in shades of orange, cherry, white, and apricot, all of which partner well with other colorful plants. Profusion zinnias are highly disease resistant and require little maintenance because they are self-cleaning; dropping their blossoms after they fade.

Small: ‘Lilliput’ are 18-24 inches with blooms that are small, round bauble-like that add interest and texture to your garden, or flower arrangements.  ‘Pulcino’ produces 18-24 inch, bushy plants that are early and prolific flowering with double and semi-double blooms. It is also known as ‘Cut and Come Again’ zinnia. 

Medium: ‘Scabiosa’ has finely textured blooms on plant 30 inches tall. ‘State Fair’ has 5-6 inch, double-flowered blooms and a bounty of colors on 30-inch robust plants that are great for cutting and enjoying in the vase.  ‘Peppermint Stick’ zinnias grow to 30 inches and are uniquely striped like a holiday peppermint. ‘Oklahoma’ series are 30-40 inches and can be obtained in several individual colors from white, pink, salmon, scarlet and gold. The flowers are 1.5 to 2.5 inches in diameter.

Large:California Giants’ are 48 inches with flowers 5 inches across; a very productive, large plant for the cutting garden. ‘Benary’s Giant’ zinnia is an award-winning variety producing large 4-5 inch diameter fully double flowers on sturdy 40-48 inch branching stems. ‘Dahlia Flowered’ zinnia grows to 40 inches and has fully doubled flowers 4-5 inches in diameter with tightly packed petals that bend downward slightly at the ends. They were developed in 1919; so definitely an heirloom. ‘Gift’ is an heirloom zinnia that is a Russian contribution with all red color and 36 inches tall with 3-4 inch flowers—a favorite of mine. Happy zinnia gardening!

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/.    

Posted in Uncategorized | Tagged , | Leave a comment

It’s time to plan for spring garden events

Spring is a busy time for garden-related happenings in San Joaquin and neighboring counties. There’s something happening nearly every weekend between now and summer, and with so many events to choose from, there are plentiful opportunities for fun and enriching outings. Consider taking advantage of these upcoming events to expand your knowledge, buy new water-wise plants, view beautiful and inspirational gardens, and more:


Classes by UCCE Master Gardeners of San Joaquin County

When:      Various dates

Where:     Various locations

Website:   http://sjmastergardeners.ucanr.edu/

Your local Master Gardeners have a wonderful series of free classes planned for spring this year. Dates and locations vary to encourage attendance throughout the county. See the Calendar of Events on the right side of our website’s home page, and click on “Show More” for additional details. Upcoming classes include “All About Tomatoes” (February 25), “Creating Your Summer Vegetable Garden” (March 9), “Planning Your Summer Vegetable Garden” (March 16), and “Summer Vegetable Garden Above the Ground” (March 24). Space is limited; call 209-953-6100 to reserve a space.


2020 Smart Gardening Conference

When:       Saturday, March 14 from 8:15 a.m. to 4:10 p.m.

Where:     Robert J. Cabral Agricultural Center

                  2101 E. Earhart Ave., Stockton

Website:   http://ucanr.edu/sgc20

This conference by the UCCE Master Gardeners of San Joaquin County features a choice of 20 garden-related presentations, to be held in two morning and two afternoon sessions. This year’s featured speaker is “Plant Lady” Marlene Simon, horticulturalist and garden columnist for the Sacramento Bee. A few presentations will be given by the local Master Food Preservers. More details to come in next week’s article!


Fair Oaks Horticulture Center Open Garden Days

When:       Saturday, March 14 from 9:00 a.m. to noon

                  Wednesday, April 15 from 9:00 a.m. to noon

                  Saturday, May 9 from 9 a.m. to noon

Where:     11549 Fair Oaks Boulevard, Fair Oaks

Website:   http://sacmg.ucanr.edu/Fair_Oaks_Horticulture_Center/Workshop_Schedule/

This center is the demonstration garden for the UCCE Master Gardeners of Sacramento County, and it boasts a water-efficient landscape, a composting area, an irrigation display, and an expansive edible garden. Each monthly event features several different, free mini-demonstrations by knowledgeable presenters. These are rain-or-shine, outdoor events.


UC Davis Arboretum Plant Sales

When:       Saturday, March 14 from 9:00 a.m. to 11:00 a.m. (members only)

                  Saturday, March 14 from 11:00 a.m. to 1:00 p.m. (public sale)

                  Saturday, April 4 from 9:00 a.m. to 1:00 p.m. (public sale)

                  Sunday, April 26 from 9:00 a.m. to 1:00 p.m. (public sale)

                  Saturday, May 9 from 9:00 a.m. to 1:00 p.m. (public clearance sale)

Where:     UC Davis Arboretum Teaching Nursery

                  Garrod Drive (across from the Veterinary School), UCD campus, Davis 

Website:   https://arboretum.ucdavis.edu/plant-sales

The semi-annual sales at this one-acre nursery feature a huge variety of offerings, including reliable California natives and plants on the Arboretum All-Stars list — those species specifically recommended for planting in the Central Valley. Arrive early for the best selection; these sales attract many visitors. View the plant sale inventory at https://bit.ly/2HxDPNP. Arboretum members (including anyone who joins during the sale) receive a discount on purchases. While you’re in the area, take time to look at the beautiful, water-wise landscaping at the nursery, visit the adjacent Mary Wattis Brown Garden of California Native Plants, or wander the Arboretum pathways along Putah Creek. 


CNPS Spring Native Plant Sale

When:       Saturday, April 4 from 9:00 a.m. to 2:00 p.m.

Where:     Elderberry Farms Native Plant Nursery

                  2140 Chase Drive, Rancho Cordova

Website:   https://www.sacvalleycnps.org/native-plant-gardening/plant-sales          

This semi-annual sale by the Sacramento Valley Chapter of the California Native Plant Society (CNPS) features a wide variety of California native perennials, shrubs, and trees. CNPS’s spring sale is held at Soil Born Farms on the American River Parkway, which features attractive native plants gardens and wildlife-friendly hedgerows (an example of conservation-based agriculture). Admission is free; proceeds from this event support CNPS’s educational and conservation work.


Gardens Gone Native

When:       Saturday, April 25 from 9:30 a.m. to 4:00 p.m.

Where:     Gardens throughout Sacramento and Yolo Counties

Website:   https://www.sacvalleycnps.org/native-plant-gardening/garden-tour

This free, inspiring, self-guided tour by Sacramento CNPS features different residential landscapes planted at least 50% with Northern California native plants. (Many gardens also include compatible water-wise plants from Mediterranean regions.) Online registration is required. A list of garden locations will be provided to registered participants closer to the tour date; every participant selects their own route and which gardens to visit. Learn how to support native pollinators and wildlife, reduce water and pesticide use, and encourage beneficial insects while meeting enthusiastic tour hosts.


San Joaquin Master Gardener Open Garden Day and Plant Sale

When:       Saturday, April 18 from 9:00 a.m. to noon

Where:     Robert J. Cabral Agricultural Center

                  2101 E. Earhart Ave., Stockton

This event showcases the UCCE Learning Landscape, a demonstration garden created and maintained by the UCCE Master Gardeners of San Joaquin County. Explore the different sections of the garden (Mediterranean, California native, pollinator, edible, and more) and get gardening-related advice from our many on-site volunteers. Offerings at the plant sale will include vegetable seedlings, culinary herbs, a variety of perennial plants, some California native plants, and a nice selection of easy-care succulents. A plant list will be posted online closer to the date of the event.

A colorful scene from a past regional garden tour, with a whimsical sculpture and many beautiful California native plants. (Photo courtesy of Kathy Ikeda)


Bringing Back the Natives Garden Tour

When:       Sunday, May 3 from 10:00 a.m. to 5:00 p.m.

Where:     Various locations in Alameda and Contra Costa Counties

Website:   https://www.bringingbackthenatives.net/garden-tour

This is another self-guided garden tour. Pre-registration is required, a $10 fee is charged for the garden guide, and a donation of $15 per person is suggested to help cover event costs. Garden access will only be granted with the tickets included in the paid garden guide.

This year’s tour showcases 35 private gardens and several East Bay California native nurseries. Garden sites for this tour are divided into two categories: “Bayside Cities” and “Inland Cities.” Be sure to visit gardens in the latter category if you’re looking for inspiration, since the weather pattern in inland Bay Area cities most closely matches the hot-summer climate in our area. Visit the website to register, view the tour flyer, and access photos and other helpful information. 

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/.

Posted in Uncategorized | Leave a comment

Reveling in warmth, hoping for cold

I enjoy mild winter weather as much as the next person. It’s so refreshing to emerge from the house on an unseasonably warm and dry day and bask in the sun’s rays while catching up on garden chores. 

People tend to think of cold weather as inconvenient at best and damaging at worst. Frigid days and nights lead to chilly hands and feet, higher heating bills, and other nuisances. In our gardens, predictions of overnight frost or deep freezes mean that we need to protect our cold-sensitive citrus trees, tender perennial plants, and outdoor pipes from damage.

Cold days might be unwelcome, but the horticulturalist in me yearns for more of them. Why, you might ask?

Cold temperatures are an essential element of the Northern California climate, and they’re actually beneficial to our native plants, many favorite perennials, and orchards. The natural yearly progression from warm weather to cold and back again triggers biochemical responses in plants that regulate their growth cycles. Cold weather is one signal that plants heed to begin their winter rest period, called “dormancy.” Like people, plants need their sleep.

The dormant period begins in the fall when the day length shortens and temperatures decrease. These changes prompt deciduous plants to drop their leaves and produce growth-inhibiting hormones. Those hormones prevent the plants from “leafing out” during the winter, even if there are periods of unseasonably warm weather. This chemical mechanism protects the plants by delaying the growth of tender new leaves, which would be damaged if the weather suddenly turned cold again. The dormant period is broken only when the plant experiences a cold spell of sufficient length to break down the hormones. This process is often referred to as chilling or vernalization. 

Such chilling is also essential to our local agricultural production. Temperate fruit and nut trees — those species that go dormant in winter but can’t survive extreme cold — need a specific, cumulative number of chill hours where temperatures are between 32 and 45 degrees Fahrenheit. Without adequate and consistent cold weather, their productivity can suffer tremendously: leaf bud growth and development will be delayed, flower buds will drop or be poorly formed, flowering can be prolonged (thus making blooms more susceptible to diseases), and fruit set will be reduced.

Some common orchard trees have high chill requirements. Depending on the variety, walnut trees need 500 to 700 chill hours to break dormancy. The ever-popular Bing cherry needs 900 chill hours to effectively bloom and set fruit. And the Bartlett pear, which comprises roughly 75% of the world’s pear production, needs a whopping 1500 chill hours each winter! On the other hand, almonds, figs, olives, pecans, and persimmons have relatively low chill needs. To read more about this topic, see the University of California’s online publication, The California Backyard Orchard, “Tree Selection” (http://homeorchard.ucanr.edu/The_Big_Picture/Tree_Selection/#chill)

A Manteca almond orchard in full and glorious bloom. (Photo by Kathy Ikeda)

Chill hours are one set of data recorded throughout the state by the California Irrigation Management Information System (CIMIS). Our local CIMIS station is located in Manteca, and during the 2018-2019 winter season — measured from the first day of November to the last day in February— it recorded 924 chill hours. During the unseasonably warm winter of 2014-2015, we had only 723 chill hours.

As of February 9 this year, San Joaquin County has an accumulated winter total of 881 chill hours. That might sound adequate, but other factors come into play as well. When cold weather is interrupted by periods of several consecutive days of warm, sunny weather, the cumulative seasonal chilling requirement can increase. Spring-like weather during winter essentially offsets some of the prior chill hours. According to the Master Gardener Handbook, “Cloudy or foggy weather that maintains temperatures below about 60°F during the day and 45°F at night is often necessary in parts of California to achieve adequate chilling hours.”

For the sake of our plants, we should rejoice in a normal season of cold winter weather.

With the certainty of warming trends due to climate change, home orchardists might want to plan ahead when selecting new fruit or nut trees. Consider planting types with naturally low chill needs, or buy fruit varieties specifically bred to have “low chill” requirements — 300 hour or less of temperatures below 45 degrees F. (Low-chill cherry cultivars have only been developed in the last couple decades.)

If we do get more near- to below-freezing temperatures this year, here are a few tips on caring for cold-tender plants:

  • Move sensitive potted plants indoors or to a protected area (under a patio cover or overhang, or against a wall that’s warmed by the sun).
  • Keep in-ground and potted plants well watered, because dry plants are more susceptible to cold damage.
  • Drape old-style Christmas lights over citrus trees and other tender plants. Unlike the newer styles of bulbs, old incandescent bulbs generate enough heat to provide a measure of protection from the cold.
  • If plants are damaged by frost, don’t remove any dead or dying growth until the risk of freezing weather is past, because the damaged leaves and stems will help insulate and protect the still healthy parts of the plant.
  • Once it’s safe, prune away all damaged parts. Dead growth will be spongy or limp, and if the bark is gently scraped away from a part of a dead stem, the color below will be black or brown. On the other hand, living tissue will be firm, and a thin layer of green will appear below the bark.
  • Avoid pruning live plants too early or heavily, because that could stimulate them to produce new, cold-sensitive growth. 

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our websitehttp://sjmastergardeners.ucanr.edu/.

Posted in Uncategorized | Leave a comment

Growing common herbs is best done by your back door.

If you like cooking with fresh herbs you can easily grow many of your own in containers or in the garden. This is much more convenient than going to the store because a recipe you want to try dictates this or that fresh herbal ingredient.  Starting herbs from seed is not difficult, but purchasing young plants at plant sales or a nursery is also an option. Every year I grow parsley, culinary sage and basil from seed for myself and for plant sales. Herbs like full sun and tolerate drought as most are native to Mediterranean climates. They also don’t need rich soil or a lot of care.

Basil is easily started from seed either in the greenhouse in early spring or later in the garden and there are various cultivars available. It is must-use-herb for many dishes.

Parsley (Petroselinum crispum) is a biennial herb of two types, Italian flat-leaf, and curly leaf parsley. The Italian flat-leaf is used for a variety of flavoring whereas the curly leaf is more often used as a garnish. Parsley seeds can be soaked overnight to facilitate germination which is slow. Plant seeds in the greenhouse 8-12 weeks before frost date at a soil temperature of 70 ºF. 

Culinary sage (Salvia officinalis) is a leafy green herb of which there are golden and purple variants if you desire more color. Seeds are planted about 1/8 inch deep and best started in February and take about 2 weeks to germinate. Soil temperatures should be 60-70 ºF. It can also be started by cuttings or layered. It is used to flavor meatloaf, stuffed pork roasts and turkey stuffing, soups and stews.

Culinary thyme (Thymus vulgaris) is a low, woody perennial, highly aromatic Mediterranean herb. The three most common varieties of culinary thyme are French, lemon, and caraway. It does well in somewhat dry, sunny conditions. It holds its flavor in cooking and blends well with the flavors of its native region, such as garlic, olive oil, and tomatoes. It can be grown from seed or propagated from cuttings.

Cilantro (Coriandrum sativum) also known as Chinese parsley is a very popular herb in Mexican cuisine and it can be grown from seeds usually planted in succession as the plants tend to bolt to seed rather quickly. If you really like Mexican food and cilantro, then it might be worth your effort to plant it over and over again. There is a slo-bolt variety, but slo-bolt isn’t no-bolt. If you don’t catch it before going to seed, no worries, the seeds are coriander another useful spice for breads, Asian, Middle East and Latin dishes as well as pickling.

Oregano is an herb used commonly in Italian, Morrocan and Mexican cuisine. There are several species and cultivars; Mediterranean or common oregano (Origanum vulgare), and a variant —Origanum vulgare Aureum, golden oregano; Greek (Oregano heracleoticum).  Mediterranean oregano can best be grown from seeds in late winter in the greenhouse with bottom heat and a soil temperature above 60 degrees. Germination takes about 7-14 days.

Sweet Marjoram (Origanum majorana) is a milder sweeter tamer version of oregano. It is started from seed much as oregano.

Rosemary (Rosmarinus officinalis) can be started from seed but is more easily propagated by using cuttings taken from a neighbor or friends plant. Rosemary seeds can take 3 months to germinate so not an easy method to pursue. Rosemary cuttings are best taken in the spring or summer when actively growing. Cuttings of young growth work best. Cuttings can be 4-8 inches long; the leaves are stripped off the lower two-thirds of the sprig leaving at least several leaves.

I use rooting hormone a powder that can be dipped into and then tapped off of the rooting portion of the twig. Rooting hormone is not absolutely necessary, but a good practice. With a pencil make a hole in the well-draining potting medium in the pot and place the rosemary cutting in the hole and then tamp down the medium. This will help keep the root hormone on the cutting.  

Water and drain well and then place a plastic bag over the pot to keep the cuttings moist and place in indirect light. When growth is observed, either by roots coming out the bottom of the pot or by tugging on the cuttings to see if rooted, it is time to plant in a larger container or in the garden. Rosemary makes a reliable shrub in the landscape. For more on herb propagation see: https://learningherbs.com/skills/herbs-from-cuttings/.

Tarragon (Artemisia dracunculus) is an herb grown for its aromatic leaves and is used to flavor dishes and is popular as flavoring for vinegar. Most tarragon cultivars can be grown from seed in the greenhouse but French tarragon, which has an especially desirable anise-like flavor, is one of those rare plants that is not grown from seeds. It must be grown either from cuttings or bought from a nursery.

May your future include growing delightful herbs.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/  

Posted in Uncategorized | Leave a comment

Seed starting time is here.

Winter is still with us, but it is time to think about the plants that we will plant this spring. Three that immediately come to mind for me are tomatoes, eggplant and peppers, a trio of vegetables in the Solanaceae family that are widely planted for summer cuisine. All are tropical plants and thrive in warm weather and they do best with long growing seasons. Hence the seeds need to get planted from mid-January to early February so that the plants are the right size to get off to a good start for early backyard tomatoes. Last year, I bought a greenhouse, but not in time to use it for last year’s seed starting.  Hence I am initiating my seed starting this year in the comforting environment of a bright warm greenhouse.

I still marvel at what happens when these little seed packets of stored DNA are planted. They are genetically programmed to replicate the species or variety as they burst forth with roots and shoots from the little embryo inside. All they need is the proper conditions of moisture, oxygen and heat. Some seeds need a little help to germinate, but tomatoes, peppers and eggplant are not among those that need to be refrigerated (a process called stratification which mimics winter) or have their seed coats scratched (scarification) to permit water to enter in order to break dormancy.  

However, if you don’t have a greenhouse and all the timers and heat-producing mats it is still possible to start seeds successfully. Tomatoes and peppers need soil temperature of about 70 degrees or more to germinate, so placing them in a warm spot in the home will work. Placing them near a heater or on the top of a refrigerator where heat from the coils rises and heats the area above it. After germination place in a warm place and provide 12-14 hours of light to keep them from getting leggy when day length is short. A fluorescent fixture with ordinary bulbs can provide the light and should be kept no more than 3 inches from the plant. A south-facing window is good for light too.

I have already assembled my containers, seed starting mix and a good number of seeds of varieties I like to grow. I collect all the half-gallon milk and juice containers through the year and I use about 50 containers because I grow plants for plant sales. I cut out one side of the containers, punch two holes in the side at the bottom for drainage and then fill with seed starting mix. I have had good luck using compost as a seed-starter for several years, but I am open to trying something new this year. The advantage in compost is that additional fertilizing the seedlings is not needed as the compost provides sufficient nutrients until transplanting.

This year I am experimenting with seed starting soil. I am dividing the containers into three groups with each to get a different soil mix: Group 1) compost; Group 2) commercial seed-starter mix; Group 3) 50=50 compost and commercial seed-starter mix. The containers are ideal for labeling with a sharpie the planting mixture used, name of the cultivar and planting date on the backside of the container (what previously was the bottom).

Many directions for seed starting recommend sterile, non-soil starting medium to avoid damping-off fungus, but I have not had a serious problem with damping off. Not overwatering and keeping the planting medium warm with heat seems to keep this fungus at bay.

While I use half-gallon cartons for a lot of my seed starting, I also reuse plastic plant containers from nurseries especially for plants that don’t like to be transplanted such as parsley. I have also used wooden flats for lettuce and other plants that don’t require as much heat to grow.

I start about 8-12 seeds per carton container. After the plants have grown to about 2-4 inches I transplant them to deep 4-6 inch pots to give the roots room to grow which is important to foster better faster growth when transplanted into the garden. After transplanting and the weather warms I put the plants outside where they can get sunlight, grow and get toughened up and ready to transplant to the garden.

If you don’t have time or inclination to grow your own tomatoes, you will have opportunities to buy plants that Master Gardeners and others have grown. The Linden Garden Club holds its annual plant sale on April 4th at Mission Hall in Linden and the Master Gardeners will be having theirs at the Ag Center on April 18th. There will be lots of varieties to check out for a happy summer of tomato, eggplant and pepper tastes as well as herbs and many other plants.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/.    

Posted in Uncategorized | Leave a comment

Euphorbia euphoria — a fascinating collection of plants

Euphorbias are simply incredible.

Over my many years of visiting various botanical gardens, arboretums, and nurseries, I’ve developed a great fondness for and sense of amazement about this genus of plants. Almost every time our family visits a new public garden, we encounter yet another Euphorbia species, and we exclaim in near disbelief, “That’s a Euphorbia too?!”

Euphorbias are an astonishingly variable and diverse group of plants, with forms that include succulents and spiny, cactus-like species; low-growing groundcovers; leafy, decorative shrubs, some with brilliantly colored, flower-like structures; tall, sculptural trees; and small, pesky, weedy species that I hope never to see in my garden again!

The genus name Euphorbia comes from the ancient Greek physician Euphorbus, who purportedly discovered the plants. The leafy, non-woody forms of Euphorbia are often called “spurges,” a name that derives from the Old French word espurgier and the Latin word expurgare. Both of these words mean “to purge,” since the sap of some Euphorbias was historically used as a laxative or purgative medication.

There are more than 2,100 identified species in the genus Euphorbia. They’re native to locations around the world, occurring naturally on every continent except for Antarctica. Depending on the species, they can be annual (with a lifespan of one year), biennial (with a lifespan of two years), or perennial (living for many years). They can also be evergreen (holding their leaves throughout the year) or deciduous (dropping their leaves seasonally). 

Despite their many differences, Euphorbias do have a few characteristics in common. One is their white, milky sap or latex. In some species this sap is only mildly toxic or irritating, but in other instances it’s poisonous, so it’s always wise to be cautious and wear gloves and eye protection when touching or pruning these plants.

Culturally, Euphorbias all require well-drained soil; many species naturally grow in poor, sandy, or rocky soils. Their water needs are generally low, and most types require plenty of sun exposure and a warm to hot, frost-free climate (although some species are cold hardy).

Plants in the Euphorbia genus also have unique flowering structures called cyathia. Each cyathium is composed of a cluster of tiny, true, male and female flowers surrounded by a cup of fused bracts (modified leaves). In some species, a whorl of larger, colorful, petal-like bracts appears below the cyathia.

The poinsettia (Euphorbia pulcherrima) — described in detail in last week’s article — is probably the best-known species in the Euphorbia genus. Another Euphorbia commonly seen in our area is spotted spurge (Euphorbia maculata), a tenacious, self-sowing, low-growing, readily spreading weed. You can learn more about this garden pest on the UC IPM website.

Besides a table-top poinsettia, my personal Euphorbia collection includes these indoor and outdoor plants:

African Milk Tree (Euphorbia trigona). This was the plant that first introduced me to Euphorbias, since I inherited a potted specimen from my paternal grandmother many years ago. It has three-sided, rigid, succulent green stems adorned with short spines and small ovoid leaves, and it has slowly branched and grown upright to nearly six feet tall. I now also have a more colorful cultivar named ‘Rubra’, which has very pretty, red-tinged stems and leaves.

A close-up photo of the red-tinged stems and leaves of Euphorbia trigona ‘Rubra’
(Photo by Kathy Ikeda)

Ascot Rainbow Spurge (Euphorbia x martinii ‘Ascot Rainbow’). This small perennial shrub has narrow, variegated leaves of blue-green and creamy yellow that emerge in all directions from long, thin, fleshy stems. Its leaves develop a glowing blush of rosy pink in colder temperatures. These plants bloom in early summer to fall, with large sprays of bright yellow-green cyathia that grow from the top of each stem.

Euphorbia Inconstantia (E. inconstantia). This is a cactus-like species that grows in a compact clump of thick, columnar, succulent, bluish-green stems. Its upright growth reaches a height of one to two feet, and the stems are deeply ribbed, with an array of sturdy grey spines emerging along the outer edge of each rib. 

A couple other noteworthy Euphorbia species are:

Pencil Cactus, Pencil Bush, or Milk Bush (Euphorbia tirucalli). This plant is spineless and isn’t a true cactus, but it does have toxic sap containing terpenes and other corrosive chemical compounds (giving it the name of “Petroleum Plant” in some countries). The species plant has bright green, thin, many-branched, vertical succulent stems that reach a height of 2 feet or more. The named cultivar ‘Sticks on Fire’ has stems that transition from bright green at the base to pink and vivid coral red at the ends. It’s a gorgeous accent plant, especially when paired with a succulent having blue-green leaves.

Crown of Thorns (Euphorbia milii). This native of Madagascar has one of the showiest flowering displays of any Euphorbia. Its woody grayish-brown stems are covered with long sharp spines, but each stem is topped with large, rich green leaves and a tight cluster of flower-like cyathia that resemble single begonias. Depending on the variety, the bracts can be pale to bright pink, intense red, creamy yellow, or variegated in color.

Euphorbia myrsinites, another noteworthy species
(Photo by Kathy Ikeda)

For more history, pictures, and descriptions of the different species of Euphorbias, consult these sources:

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website.

Posted in Uncategorized | Leave a comment

Poinsettias: history, fun facts, and more

Poinsettias have become a symbolic plant during the holiday season, their deep green leaves and bright red rosettes adorning tables and windows across the country. Marcy Sousa’s recent column briefly discussed the care of this and other ubiquitous Christmastime houseplants, but let’s take a closer look at this unique plant species.

Poinsettias (Euphorbia pulcherrima) are evergreen to semi-evergreen, perennial plants with woody stems. They’re native to tropical, mid-elevation regions and dry interior forests of central Mexico, where they grow as shrubs or small trees. In their natural habitat, they have open, “leggy” growth and can reach a surprisingly large size, reaching 10 to 15 feet tall and six or more feet wide. 

Brilliant red poinsettias growing in a greenhouse (Photo by Kathy Ikeda)

We enjoy poinsettias for their showy winter display of large, deep green leaves and bright red rosettes. But the vividly colored structures that are commonly thought of as flower petals are actually modified leaves called bracts, and not part of the flower at all. The true flowers are the tiny, yellow-petaled, inconspicuous structures found in a tight cluster surrounded by the bracts. 

If you’ve ever pruned a stem or broken off a piece of this plant, you’ll know that it has a thick, white, milky sap that oozes from damaged or cut surfaces. This sap sometimes causes skin irritation, but it isn’t poisonous, and if ingested it usually doesn’t result in anything worse than mild stomach upset or nausea. (The leaves taste awful.) This milky sap is typical of most plants in the Euphorbiaceae or Spurge family, to which the poinsettia belongs.

People of Mexico’s early Aztec culture prized these colorful plants, and cultivated them to produce a medicinal compound and a reddish-purple fabric dye. In the Aztec language of Nahuatl, the plant was named Cuitlaxochitl (from “cuitlatl”  for residue or soil and “xochitl” for flower). Poinsettias didn’t become associated with Christmas until the 16th or 17th century, when Franciscan priests near present-day Mexico City began to use them in nativity processions.

Joel Roberts Poinsett, a botanist and physician from South Carolina, introduced the plant to the United States in 1825 while he was serving as the first U.S. ambassador to Mexico; the plant’s common name in English-speaking countries is derived from his surname. He died on December 12, 1851, a day now commemorated as Poinsettia Day. 

A German immigrant family by the name of Ecke was instrumental in creating America’s commercial poinsettia industry over 100 years ago. The Eckes became the dominant force in breeding, growing, and establishing the popularity of the poinsettia in the United States, and the Paul Ecke Ranch in San Diego County, California now grows more than 70 percent of poinsettias sold in America each year. The Eckes and other breeders have developed numerous named cultivars of this plant over the years, including plants with atypical bract colors (such as white, yellow, pink, burgundy, and salmon), different bract patterning (speckled, bicolor, and multihued), and double-bracted and miniature forms.

In the last two centuries, the poinsettia has been elevated from a little-known exotic plant to one of the most important and commercially valuable plants in the U.S. floriculture industry. With annual wholesale sales of roughly $60 million—occurring mostly in the six-week period before Christmas—and a contribution of more than $250 million to America’s retail economy, the poinsettia far outpaces the sales of its closest competitor, the orchids. 

Like many plants, poinsettias are photoperiodic, meaning that their growth cycle responds to the seasonally changing length of light and dark periods during a day. However, poinsettias are also in a smaller group known as “short-day” plants, meaning that they naturally flower in the winter and they need to have less than 12 hours of light per day (and nearly total darkness for the rest of the day) in order to begin the bloom cycle. Most poinsettias develop their full color from 8 to 9 weeks after the flowering cycle is initiated, depending on the variety. Once full color is reached, plenty of light is needed to maintain the bright hues.

A poinsettia plant just beginning to develop color in its upper bracts. (Photo by Kathy Ikeda)

Commercial growers use a very specific and carefully timed regimen of pruning, fertilization, pest management, and controlled exposure to artificial light in order to develop the uniform looking, cheerful plants we see in stores and nurseries every year. New poinsettia plants are generally grown by taking cuttings from the stem ends of mature plants, but many cultivars are patented and they shouldn’t be propagated by anyone other than the patent holder.

Poinsettias prefer soil on the dry side and don’t like “wet feet” or soggy soil. They’re also easily stressed by lack of sufficient water, and will drop leaves and bracts readily if the soil is too dry. Monitor the soil moisture of potted plants carefully to keep them in good health. 

Poinsettias are usually treated as throwaway plants, discarded in the trash after the holidays. However, with proper care and attention, they can be maintained as houseplants for repeat performance of bloom. In some areas, they can also be planted in the garden. 

According to the Sunset Western Garden Book, poinsettias aren’t suitable for outdoor planting in our climate zone because we get below-freezing temperatures each winter. However, they could be grown successfully as outdoor potted plants if the pots are placed in a sunny location and are moved to a warm, protected area during the colder months of the year.  The garden guide’s growing instructions include these tips: “Thin branches in summer to produce larger bracts; or prune them back at 2-month intervals for bushy growth and smaller bracts. To improve red color, feed every 2 weeks with high-nitrogen fertilizer, starting when color begins to show.”

Enjoy the cheerful colors of poinsettias while they last, and if you want to try a fun experiment, try growing your 2019 plants as a “Happy New Year” project during 2020!

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/.

Posted in Uncategorized | Leave a comment

Time to think about garden plans.

It is almost winter or what counts for that mild season in California; a good time for taking stock of our gardens and plan for next year. What do I want to plant for next year? What seeds do I order and do I want to change the landscape or some aspects thereof next year? Winter is a good time to think about what next year’s garden could feature in terms of texture, color, cutting flowers, vegetables, and fruit or other landscape aspects. It is also a good time to plant perennials, fruit trees and roses that can get their roots established before next summer.

For example, I am considering doing away with a large, lush grass feature and replacing it with a dwarf citrus tree. The childhood farm boy in me enjoys things edible over an ornamental grass even though the ornamental grass likely doesn’t demand a lot of water nor is it unattractive.  When I moved here I removed oleanders and fruitless olives and replaced them with 5 Citrus trees, a Santa Rosa plum, and three peach trees. I also grafted two flowering plums to Laroda plums. Do I really need another citrus or something else? I need to think more about this.

I also love flowers and new Dahlia catalogues are winter arrivals that provide an opportunity to order some that I don’t have or to replace favorites lost along the way. I already have more than enough tubers to fill all of my available dahlia sites, but I could not resist ordering several that I don’t currently have. I noticed that some of the new dahlia offerings cost 30-35 dollars; which I find to be a bit pricey and who knows how well they might perform? Based on past experience, they are likely to be much more reasonably priced in next year’s catalogue, so being patient can be prudent. 

As a garden club member I once completed a National Garden Club sponsored four week-end course in Landscape Design, but I have to confess that I never became a practicing Landscape Design Consultant which was the aim of the course. It was a great course taught by a Landscape Architect from UC Davis. I learned a lot, but I always felt that the certificate of achievement and a couple of bucks would get me a cup of coffee.

We all love certain plants and it is a matter of our personal preferences how we organize them in our landscapes. However, it is a good idea to follow principles of design which will make the landscape organization functional as well as esthetically pleasing, see: https://www.gardendesign.com/landscape-design/rules.html. This garden design site also contains several suggestions for planting perennials and other plants in your garden.

Some landscape design ideas might include a pollinator garden, a butterfly garden, a beneficial insect garden, a native plant garden, a theme garden such as a Japanese garden or some combination thereof. For a butterfly and native plant garden ideas see: https://www.cnps.org/gardening/gardening-for-butterflies-3106

A mostly native landscape front yard was created at my new home before I bought it and we love it. No lawn to mow and an easy maintenance attractive front yard with lots of blooming shrubs, perennials and ground covers to enjoy. Each fall we especially like the vibrant red-orange, trumpet-shaped blossoms of California fuchsia (Epilobium canum) which is a drought tolerant, deer-proof native plant. The California Native Plant Society has lots of information on native plants at: https://www.cnps.org/gardening.

For ideas on new plants and design ideas there are lots of books, magazines and on-line resources to help. It is amazing how many garden books there are and many are redundant in what they cover, but they just keep coming because there is always such great interest in gardening. Unfortunately, a lot of gardening books, articles, ideas and advice pertain to gardens not in California and we have a special mild Mediterranean climate that often demands different plants and plans than those recommended in other places. Sunset Western Garden Book is great resource for California gardeners and it expands with each edition to cover new plant introductions. A website that features lots of information on California unique gardening requirements is this UC website: http://cagardenweb.ucanr.edu/General/.

Bareroot season is coming so it is a good time to consider adding shade trees, fruit trees and roses to your landscape. California is a great place for fruit trees as so many do well here including Citrus as per Kathy Ikeda’s recent column on fruit trees. Happy garden planning.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/ .

Posted in Uncategorized | Leave a comment

Pruning crape myrtles without murdering them

Winter time is here and it is time to think about pruning our ornamentals, roses and fruit trees. Crape myrtles (Lagerstroemia indica) are a wonderful ornamental tree commonly planted in our area. It has bark that is attractive; blooms from about July until fall in colors of white, pink, purple, crimson and comes in a range of sizes from 4 to 30 ft. tall. Plant breeders have been busy with this species. They are drought tolerant as well as beautiful and also have colorful fall foliage in reds, yellows and orange.

I have written before about folks committing crape murder. I can testify that I still see it being committed so I am addressing this issue again. Crape myrtles can be left unpruned and have a nice natural shape. However, since blooms occur on new growth they are often pruned to stimulate new growth for blooms. The problem is how to foster new growth without disfiguring and diminishing the health of the tree.

Often pollarding is the approach used to commit this crime. Pollarding is defined as a tree cut back nearly to the trunk, so as to produce a dense mass of weak, new-growth branches. It is like kneecapping the tree. Perhaps Wikipedia says it best about pollarding crape myrtles “This is not a practice to use if one wants an attractive, healthy natural tree as the natural growth is stunted. Many times this is done in southern states of the USA to crape myrtles, and is called ‘crape murder’ by some.”  

I prefer to train crape myrtles like a fruit tree with an open center. This openness allows sunlight and air into the center, reducing diseases such as powdery mildew and promotes new growth for blooms. A heading cut on a young tree at about 3 to 4 feet will create branches to be trained to an open vase. After selecting a single trunk, it is a matter of making choices of which of the new shoots will be selected to create the vase shape of the tree. Select no more than 3-5 main scaffold branches. I usually head prune these at 2-3 feet the following year to produce secondary scaffolds. At some point when the tree is shaped and the secondary scaffold branches are at a sufficient height, I truncate these branches to a two bud spur.

The choice is often for spurs which will keep the tree opening up. Pay attention always to which way the buds are facing on your two-bud spur selection as well as scaffold selections. Buds are usually located opposite each other in alternating sets, i.e., the next set is 90 degrees from first, so in some cases leaving 4 buds will provide the best directions for the shoots because these top buds will usually dominate. Last year’s two-bud spur may produce two or three shoots, so you will need to reduce this to one shoot from which to select the next two-bud spur.

You can keep the tree at whatever height you want. By selecting two bud spurs on each branch each year, you will only add about a foot to the tree in 6-8 years. If you want to shorten the tree you can cut back into old wood and the tree will push some vestigial buds and continue to bloom. Thus this method allows you to keep the tree at a reasonable height and looking attractive.  Keeping the tree short so you don’t need a ladder is safest, but a ladder can be used too.  

There is a tendency for the crape myrtle to have multiple trunks, but as I stated above I prefer to select one main trunk and work with it. However, you can create an open vase tree with multiple trunks from the ground, especially if you start to work with a tree established in this manner: see http://www.finegardening.com/pruning-crape-myrtles.  Select no more than 3 to 5 well-spaced trunks and prune out the rest. Crape myrtles often send up suckers near the base which should also be removed.

At my new home, I have two crape myrtles that were established with multiple trunks. I would estimate that they are perhaps 12-15 years old and had not been pruned, so I was challenged to shape them to my fancy. There were crossing limbs, too many limbs and a densely crowded top of branches. After pruning they had an open vase shape with a thinned top. I also prune weak side growth to strengthen it and induce more vigor. This will help provide blooms in places other than just at the treetop. More evenly distributed blooms are more appealing. Cheers to better pruning and enjoyment of crape myrtles.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website:  http://sjmastergardeners.ucanr.edu/CONTACT_US/

Posted in Uncategorized | Leave a comment

Winter pruning of fruit trees

We’re fortunate to live in California’s Central Valley—one of the most fertile agricultural regions in the country—and thus we have the ability to grow a huge variety of fruit- and nut-bearing trees. Stone fruits (apricots, cherries, nectarines, peaches, plums), pome fruits (apples, pears, Asian pears), nuts (almonds, walnuts, pecans), and others (figs, persimmons) all do very well in our climate and soils.

Knowing how and when to prune these types of trees is essential to their successful establishment, their long-term health, and their productivity.

Careful, purposeful training of fruit trees during their first few years of life after planting is crucial to having a well structured, healthy, and high-yielding tree in later years. Generally speaking, fruit trees should be trained to have a few main branches that emerge low on the trunk, for easier access when pruning and fruit-picking, at a 45 degree angle for good strength. These main or “scaffold” branches should form an open, un-crowded framework, to allow for proper sun exposure and air circulation within the tree. Shaded and/or crowded branches will eventually stop bearing fruit.

Fruit trees can be trained into several forms: vase-shaped, central leader, Y, or espalier. The pruning methods and timing for creating these forms vary and is too complex to cover in detail here. Consult one of the sources listed below if you have a young new fruit tree and want to know how to effectively “parent” it during its adolescent and teenage phases.

Mature, deciduous fruit trees—those fully grown trees that lose their leaves and go dormant during the cold winter months—can be pruned during the months of December, January, and as late as mid-February, while their branches are bare. Late January is our best month for pruning deciduous fruit trees, since it’s well into the dormant season but before the buds begin to swell. Avoid pruning on foggy or rainy days or when the trees are moist, since damp conditions can spread pathogens into freshly cut wood.

Depending on the kind of fruit tree, between 20% to 50% of the prior year’s growth should be removed to encourage the best fruit production. Consult the references mentioned below for specific recommendations.

(Image courtesy of UCANR)

When pruning, pay close attention to the location of the buds along the branches. All pruning cuts should be made no more than ¼-inch beyond a bud; don’t leave long stubs of branch without buds. Also pay attention to the orientation of the buds; they produce growth in the same direction they point, and it’s best to end the branch with an outward facing bud. New branch growth emerges at the location of the cut (not closer to the trunk), and the more buds cut off the end of the branch, the more vigorous the new growth will be.

Some types of growth should be removed completely: dead wood, damaged or diseased branches, suckers (small, vigorous, weakly-attached sprouts that emerge from the root line or trunk), downward growing branches, or branches that cross over others. When removing entire branches, make the cut at the attachment point but just beyond the ring of thickened tissue at the base of the branch; preserving this “branch collar” will help maintain the tree’s ability to heal itself. Don’t leave long stubs, and allow cut surfaces to dry out and seal naturally.

Fruit trees can also be pruned during the growing season while leaves are still on the tree. However, this should only be done under limited circumstances, such as to train a young tree or to slow or correct the growth of a too-vigorous or overgrown older tree. Do this type of pruning in late summer after fruit has been harvested.

One principle to remember when pruning actively growing trees, whether fruit or other: don’t remove more than one-third of the crown (the upper,  leafy part of the tree) at a single time.  When pruning mature leafy fruit trees, it’s best to remove no more than one-tenth of the overall growth. The leaves are where the process of photosynthesis occurs, and if too many leaves are removed at once, the tree’s capacity to produce its own food (carbohydrates) and your food (fruit) is drastically reduced. This in turn will cause a significant portion of the tree’s root system to die, which makes the tree more susceptible to underground fungal infection, internal rot, and even death after a few years. 

Another very important caveat is to use well-maintained pruning tools. Cutting plant stems or branches with dull and dirty hand pruners, loppers, or pruning saws is the equivalent of performing an operation with rough-edged, unsterilized surgical implements. Neat and clean pruning cuts help prevent excessive damage to a tree’s living tissues, and that in turn allows the tree to heal its wounds and recover quickly.

Using hand pruners to remove an inward growing branch on a fruit tree (UNANR)

Before you head out into the garden for your annual fruit tree maintenance project, grab a sharpening stone and use it regularly and frequently as you shape your treasured trees. Remove dirt and debris from pruning tools and scrub them with hot soapy water both before and after use, to keep them and your trees in good condition.

Disinfection of pruning tools is usually recommended only when working on diseased trees or shrubs. This can be done by soaking tools for at least one minute in a solution of 1 part denatured alcohol to 9 parts water, or by spraying them with a household aerosol disinfectant. 

These wintertime pruning recommendations do NOT apply to citrus trees: oranges, tangerines, lemons, limes, grapefruits, kumquats, etc. Citrus trees are evergreen (keeping their leaves year-round) and they don’t need regular, annual pruning. If citrus trees need thinning, do it in warm weather: either in the spring before trees bloom, or in late summer after harvest. This prevents any tender new shoots from being damaged by winter frosts or frigid winds.

For those of you who want to grow trees that reward you with homegrown, healthy food, here are a few great resources:

  • The Home Orchard: Growing Your Own Deciduous Fruit and Nut Trees, by the University of California, Agriculture and Natural Resources (UCANR) — UCANR Publication 3485. This book was written specifically for backyard orchardists, and it covers a full range of helpful topics, from the planting and care of young trees to the pruning and harvesting of fruit from mature trees.
  • Growing Your Backyard Orchard (http://sjmastergardeners.ucanr.edu/Growing_fruits_in_your_backyard_orchard/), a webpage of the San Joaquin County Master Gardeners. This site has links to a wealth of information, including several publications about pruning fruit trees of different ages and conditions; calendars of operations for different types of fruit and nut trees; information on pests and diseases; fruit preservation guides; and much more.
  • Fruit Trees: Training and Pruning Deciduous TreesUCANR Publication 8057 (http://homeorchard.ucdavis.edu/8057.pdf)
  • Peach Leaf CurlUCANR Publication 7426 (http://ipm.ucanr.edu/PDF/PESTNOTES/pnpeachleafcurl.pdf). This fungal disease causes severe leaf distortion on peach and nectarine trees; post-pruning treatment with an appropriate antifungal spray is recommended during the dormant season.
  • An Illustrated Guide to Pruning, by Edward F. Gillman. This is an exhaustive and beautifully illustrated manual on anything you’d ever want to know about pruning trees and shrubs. Widely used as a horticultural textbook, it’s also an invaluable reference book for both homeowners and landscaping professionals.
  • Winter Fruit Tree Pruning 2012 (https://www.youtube.com/watch?v=EpU8W-H5xZ4).  This video by Dave Wilson Nursery, although not an endorsement, provides a very good visual overview of early fruit tree pruning.

Whether you have only one fruit tree, are beginning to plant a home orchard with many different trees, or have several established trees, use the late fall and early winter months and these excellent reference guides to prepare for upcoming pruning tasks, and then enjoy a bountiful harvest in 2020.

For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website: http://sjmastergardeners.ucanr.edu/.

Posted in Uncategorized | Leave a comment
  • Categories

  • Archives