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/.

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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/  

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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/.    

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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.

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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/.

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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/ .

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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/

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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/.

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Loving trees is good for the spirit.

Recently, Andrew Carmichael, a Master Gardeners who is also a certified arborist among many other accomplishments provided our monthly meeting education lecture.  He spoke about the aesthetics of trees and about how if you really love trees you will both care about them and care for them. I was in total agreement with his views on trees. The next day, my Linden Garden Club had a nurseryman speaker who also advocated for planting trees that do well in the Central Valley especially for colorful fall foliage. It was a week for a tree lover to be re-inspired by information on trees to grow and how best to care for them.

My affection for trees began as a child on a 165 acre farm in New Jersey. We had a forty-acre woodlot and when I got home from school, I put on my work duds and with my dog went to the woodlot to enjoy nature and especially the trees. There were tulip poplars, red oaks, white oaks, blackjack oaks, pin oaks, persimmons, flowering dogwood, white cedars and others as well as a white pine/Norway spruce Christmas tree plantation that my father had planted in 1944 on some land that was no longer farmed due to erosion.

I also remember one large, dead American chestnut that still stood upright like a white bleached ghost in the forest. It was a casualty of chestnut blight caused by a fungus organism accidentally introduced in 1904 on some nursery stock. It spread rapidly and killed an estimated four billion of one of the best trees in our native forests by 1940. Chestnut wood was good for furniture, rail fences, lumber, and the chestnuts were good “roasting by the fire.”  The tree was also a good shade tree as recognized in Longfellow’s poem: ‘The Village Blacksmith:  Under a spreading chestnut tree the village smithy stands’. My father, who witnessed the whole sad chestnut blight saga unfold, informed me about why the dead ghost chestnut tree was in our woodlot as well as how important chestnut trees had been.

Chinese chestnuts were introduced for providing edible chestnuts but do not replace other qualities of the American chestnut. For many years there have been efforts to breed a disease-resistant American chestnut and recent efforts at genetic engineering will hopefully bring back this wonderful tree: https://www.sciencemag.org/news/2018/08/save-iconic-american-chestnut-researchers-plan-introduction-genetically-engineered-tree.

Here are some thoughts on planting and caring for our trees. Plant them in the right place which is a basic gardening axiom: “right plant right place.”  Don’t plant a potentially large tree close to your home, power lines or other service lines. See PG and E guidelines for trees: https://www.pge.com/pge_global/common/pdfs/safety/yard-safety/powerlines-and-trees/Bay-Area-Small-Trees.pdf.  I would avoid trees vulnerable to diseases or pests such as the Bradford Pear which is susceptible to fireblight. The American sweetgum (Liquidambar styraciflua) produces spiny seed fruit “gumballs” that are no fun to step on or rake up by the hundreds. I recently removed one for that and other reasons, although I did enjoy the fall foliage and the shade. I have yet to choose a replacement, but there are lots of good fall foliage trees to enjoy and there is now a sterile, non-fruiting sweetgum variety ‘Rotundiloba’ which ends the gumball problem.

Japanese maples can show a range of fall colorsHybrids of silver and red maples have been developed that are good for fall foliage and a red maple is more drought tolerant than these hybrids which have glowing names such as: ‘October Glory’, ‘Autumn Blaze’, ‘Autumn Fantasy’.  They are all about 50 feet and 30 feet wide. October Glory’s leaves stay on the tree later into the fall than other cultivars. Ginkgo biloba is an ancient tree that has proven to be a colorful fall foliage tree and it is resistant to pollution and pests though it grows slowly. Chinese pistache, crepe myrtles, ash, Eastern redbuds and tupelos are some moderate-sized trees with colorful foliage.

When planting a tree it is best to plant on a small undisturbed soil pedestal under the root ball to assure that the tree does not sink to a depth below where it was planted in the nursery; very important for grafted fruit trees. Also, do not add soil amendments but use native soil in the planting hole so that roots are encouraged to spread.

Joyce Kilmer, a romantic poet killed in WWI, expressed well my sentiment on trees: “I think that I shall never see/ a poem lovely as a tree.”  May all your trees be colorful, fruitful, shadeful and poetic.

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/

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Multiply and share your perennials this fall

Gladiolus are beautiful to share with friends.

Have your favorite perennials been looking crowded and not blooming as abundantly as they used to? Maybe it is time to divide them and replant or share them with neighbors or friends. There are actually tables that will tell you how often you should divide your German bearded irises (Iris germanica), daylilies, Coreopsis, Pentstemons, Shasta Daisy, Delphiniums, Achillia (yarrow), Agapanthus and many other perennials; see this table resource for information on dividing over 100 perennials: https://docs.google.com/spreadsheets/d/1Sv07afJ8jz9h_CGA_NNdjuFcaV83BUXtT2uIsYUsNdI/edit?ts=5c478a81#gid=1250055917.
Most spring and summer blooming perennials are best divided and replanted in the fall. This is a good time because they are not blooming so energy can go to establishing roots and leaves before winter sets in. Fall bloomers can be divided in the spring. It is good to irrigate a day before digging and it may also be good to trim foliage back moderately for some plants.
Plants should be dug with a shovel or a spading fork. For very dense clumps it is sometimes necessary to use back to back spading forks to pry clumps apart after digging them out or use a hori-hori Japanese gardening knife to tease them apart or a shovel to cut them apart. Some fall perennials have spreading root systems; aster, bee balm, lamb’s ear, and purple cornflower are examples. These plants can easily be separated by hand or cut apart. Each new plant should have 3-5 vigorous shoots and discard non-vigorous plants.
Another perennial group to divide in the fall has clumping root systems that originate from a central clump with multiple growing points. This group includes astilbes, hostas, daylilies, and many ornamental grasses. Keep at least one developing eye or bud with each division. If larger plants are wanted, keep several eyes.

‘Smokerings’ is a prolific iris that will need to be divided every 3 years.

Irises have rhizomes that grow at the surface and as they get crowded, bloom less. They are usually divided every 3 years. The best time to do this is in late summer, but fall is alright too, especially if you have repeat bloomers which should be divided after blooming. Rhizomes should be lifted with a shovel, cleaned and examined. Often rhizomes older than one year without leaf fans attached are shriveled with poor roots. These should be discarded and only rhizomes that are young, healthy with roots and one or more leaf fans attached should be replanted.
Peonies and other plants having a taproot and are not easily divided. Peonies can stay in one place for a 100 years and not get crowded, but if you take care they can be divided and they must be planted at the same original depth where they previously were growing.
Dahlias are a special case that are dug and divided late in the fall. They can be dug a couple of weeks or more after frost kills the foliage. The tubers can be divided after being dug and washed or they can be washed, stored and divided later in the spring when the eyes are more evident on the tubers.
Dahlias can also be left in the ground in the Central Valley since the ground here does not freeze as in most parts of the country. In New Jersey, my mom had to dig them every fall and put them in the cellar away from killing freezing temperatures. However, they are vulnerable to rotting in wet winters here so you take your chances when not digging them. I accept that I might lose a few when I don’t dig them, but always hope my favorites will survive. After 3 years of not being dug they will likely get crowded and need to be dug and divided.
Agapanthus is another flower that will need dividing every few years or the blooms will get sparse. Instructions on how to do this can be found at: https://www.gardenandhome.co.za/gardening/how-tos/how-to-divide-agapanthus/
Gladioli are a drama flower I like and they can be dug annually or left in the ground, but if left in the ground they should be divided every two years. Dividing gladiolus will provide double the corms and double the pleasure of growing these gorgeous flowers. I used to leave a few in the ground each year to make sure I had some in bloom to enter in the County Fair Floriculture exhibit each June. I won a lot of best of show ribbons with

Best of Show-San Joaquin County Fair-2005

these beauties. Alas, the floriculture exhibits were discontinued for several years and this year although it was resumed, they had zero entries. Apparently, discontinuity is the enemy of good participation.
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/

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