Gardening is a lifelong learning experience

Most of us find gardening a challenge.  So many plants to know and choose from, so many configurations of plants possible and so many things to consider, sun exposure or shade, plant textures, flower colors and advancing verses receding colors. What type and amount of hardscape and paths to include and also styles of gardens and themes, such as pollinator gardens or native plant gardens or Japanese gardens. Landscapes that are bio-diverse are also the best because they help minimize some pests and pest damage as well as being aesthetically pleasing.

Having downsized in this past year to a smaller home and garden, I have a new garden to work in and to learn new ways to garden. Fortunately, the previous owners did a wonderful job of landscaping with a mostly native plant garden in the front and in the back are roses, flowers for pollinators and an area for composting and vegetable growing in raised beds. I added 3 more raised beds making 9 in total. I like to grow a variety of musk melons which takes up nearly two raised beds.  Corn and pole beans take up a lot of room so I gave up the pole beans and the corn in favor of melons and of course dahlias which you can’t buy at the local market.

Gardening is a lifelong activity that requires continued learning and exploration.  It can be a challenge for our brains to keep us young in spirit as we age. Recently, I judged 4-H entries in the youth floriculture show at the Stanislaus County Fair in Turlock. I enjoy my flower judging activity and it can be a learning experience for me as well as for the kids entering their flowers. I score them less than first place for flowers entered past prime, deformed, ungroomed or so short-stemmed that they barely peep out of their containers.  However, most of the entries get a first place and hopefully those getting second place will improve their showmanship next time.

Mexican Bird of Paradise is a collage of bright golds and reds.

At this show, I was treated to two flowers which I had never seen before. I suspect that more than one 4-H kid came from a family growing these flowers as there were four entries each of these unusual flowers. A white cactus flower that was awesome as well as a Mexican Bird of Paradise, which I later discovered is a drought tolerant shrub native to the Mojave Desert. The exact white cactus flower that I saw was not easily identified in Google images as there seem to be several so named. There were also lots of zinnias, dahlias, marigolds, lilies and crepe myrtles which kept me busy for 2 hours scoring them all. It is inspiring to see such interest in flowers by youngsters.

We also need to learn to better use our landscape watering. In our Mediterranean California climate where water supply is getting scanter, water conservation in our landscapes is very important.  Water use per person per day for Californians in July 2016 was about 113 gallons. Traditionally, about 53 percent of household water use is on the landscape. It has likely improved

White cactus flower is about 5 inches in diameter and is awesome to behold.

since then with reductions in lawns and water needy plants.

Recently, at midafternoon and with temperature exceeding 100 ºF; I drove by a yard in my neighborhood where lawn sprinklers were running. When humidity is low and temperatures high,   evaporation is also high. Perhaps 30 percent of the water being applied in the heat of the day is evaporating and not reaching or helping the lawn. To be smart at minimizing evaporation and maximizing efficient use of irrigation water, it is best to water between 4 AM and 8 AM. Watering in the evening is more apt to promote water borne diseases than watering in the early morning and watering in the heat of the day definitely wastes water.

With irrigation controllers it is not hard to be consistently correct with watering times. Also, if you are watering a steeply sloping bank or have heavy clay soils, it is possible with a controller to water for short periods interspersed with no watering periods so that the water has a chance to infiltrate rather than run off.  For more tips on water conserving landscape plants see: Here is to both life-long garden learning and water conservation in your landscape.

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:

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Become a UC Master Gardener

If you love to garden, have an interest in lifelong learning, enjoy sharing your knowledge and are committed to community service, the Master Gardener program is the place for you. Master Gardeners are community members who love gardening and are enthusiastic to share their knowledge with others. This program offers comprehensive training in the best home gardening practices and an opportunity to use your knowledge in service to your community. Master Gardeners are helping home and community gardeners reap the maximum benefits and enjoyment from gardening.

The mission of the San Joaquin UC Master Gardeners is to extend research-based knowledge and information on home horticulture, pest management, and sustainable landscape practices to the residents of San Joaquin County. UC Master Gardeners extend research-based information by conducting workshops and demonstrations, diagnosing plant and pest problems, speaking to community groups, utilizing social and print media,  educating teachers and parents at school gardens, and answering gardening questions at local fairs and farmers markets as well as on our email and phone helplines. Master Gardener volunteers help empower neighborhoods to foster healthier gardens, communities and a sustainable environment.

The Master Gardener program began in Washington State in 1972 and quickly expanded to other states. The first University of California programs were established in Riverside and Sacramento counties in 1980. San Joaquin re-launched its program in 2007 and since then, the San Joaquin Master Gardeners have volunteered over 53,000 hours and have earned over 14,700 continuing education hours. The program is funded by the cities and counties of San Joaquin and AB939. We are excited to announce the Stanislaus County will be starting a Master Gardener Program and San Joaquin County will be training those volunteers to help get their program up and running.

Our next training will begin in January 2019 and is open to residents of San Joaquin and Stanislaus counties.  Prospective Master Gardeners will attend an orientation meeting in October and are then interviewed to make sure that they are willing and able to complete the volunteer commitment. Those who enter the program must commit to donating a minimum of 50 volunteer hours the first year to Master Gardener public education projects and 25 hours every year after along with earning 12 hours of continuing education.

The training program will be an extensive 19-week course providing a practical overview of horticultural and sustainable landscape practices. Training sessions meet Wednesdays from January 30 to June 5. Classes are taught by experts from the UC faculty and staff, landscape and nursery professionals, local horticultural educators and certified Master Gardeners that are outstanding teachers, who inspire students. Trainees must pass the weekly quizzes and take home final exam with a 70% or better. Classes will be held on the Robert Cabal Agricultural Center in Stockton. Applications may be downloaded from our website or picked up at our office. The registration fee for this program is $180, which includes a copy of the UC Master Gardener manual as well as other UC home horticulture books and covers class supplies.

After completing this training, newly certified Master Gardeners possess not only increased knowledge but, most importantly, an understanding of how and where to find accurate information to share with the public on all kinds of gardening topics. As a bonus, you also have a group of new friends who share the same interest, enthusiasm and dedication to helping the public. You get to meet other like-minded people as well as learn how to have healthier plants, healthier gardeners, a healthier environment and a healthier community and you choose projects that fit your interests, abilities and skills.

If you want to get involved in your community and enjoy preserving food, the UC Master Food Preservers are also accepting applications for their 2018 training that begins in September of 2018. More information about their program can be found on their website,

More information about our program and the next training can be found on our website. If you have questions, feel free to contact the Master Gardener Helpline at 209-953-6100.





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The carpenter bee – friend or foe?

We usually think of carpenter bees as those bulky, black bees that buzz loudly around our yards and burrow into wood, earning them a reputation as pest insects to be eliminated. You might be surprised to learn better side of these interesting native bees!

Three different species of large carpenter bees live in California, all belonging to the genus Xylocopa. The one usually seen in our area is the Valley carpenter bee (Xylocopa varipuncta). The females of this species are common and instantly recognizable: black and slightly hairy, with black eyes and shimmering dark wings.  The males are seldom seen but stunning: slightly fuzzy and rich golden-brown in color, with a yellowish head and mesmerizing olive green eyes. Their appearance has earned them the moniker “teddy bear bees.”

Valley carpenter bees (Xylocopa varipuncta). On the left is a black female dusted with yellow pollen (perched on a passionflower, with a honeybee in the background). On the right is a golden-brown male (perched on the flower spike of a Mexican bush sage). Photos © Kathy Ikeda

Despite their somewhat startling size and sound, these carpenter bees aren’t as scary as they might appear. Male carpenter bees can’t sting, and females will sting only if disturbed (and even then, that threshold is high). Their large body size and relatively small wings make their flight look aerodynamically impossible and even comical at times!

Large carpenter bees have earned their name — and a bad reputation — by their practice of nesting in wood. They don’t construct hives like honeybees; instead, the females use their strong mandibles (jaws) to chew a small round entry hole and a narrow, six- to ten-inch-long tunnel into soft wood or the trunks of dead trees (cottonwoods and plane trees are favorites). They then use the leftover sawdust from tunnel excavation to wall off a series of brood cells inside the tunnel. A large mass of pollen and nectar is deposited in each cell, then a single large egg is laid on each mass. The eggs soon hatch and develop into adult bees, which remain in the nest until spring.

Preventive measures are the best way to prevent any structural damage from carpenter bees. They won’t disturb painted, varnished, or treated wood and they will avoid holes and cracks that have been sealed or caulked, so regular home maintenance is an effective deterrent. They also won’t tunnel into composite wood decking. Steel wool stuffed into the nest entry holes will discourage carpenter bees from returning, but the nests must be empty for this technique to work. For more specific information, visit the University of California Integrated Pest Management (UC IPM) website:

Pest control companies used to recommend insecticidal sprays and dusts to eliminate carpenter bees from homes, decks, and other wooden structures. Fortunately, that practice is changing as researchers learn more about carpenter bees’ habits and their beneficial role in our natural ecosystem. As one expert notes, “their contribution to pollination far outweighs any damage to structures.” Also, our California carpenter bee species are far less destructive than other species in the eastern U.S.

Chemical control should never be used as a first line of defense against carpenter bees, because the recommended insecticides also can be lethal to honeybees and a wide range of other beneficial insects (See

You can encourage large carpenter bees to nest in a non-damaging way by placing a scrap piece of untreated 4×4 redwood post or a log section in a sheltered place in your garden, and pre-drilling it with some shallow holes. The bees will find and enlarge the holes.

California is also home to thirteen bee species in the genus Ceratina, collectively known as small carpenter bees. They look nothing like their better-known relatives; they are tiny (less than ¼ inch long), have narrower abdomens, and are metallic greenish-black in color. They bore into and build their nests inside pithy or soft-cored stems of plants such as elderberries, agave, cole crops (Brassica), and sunflowers. This nesting behavior does not harm the plants.

Both the large and small species of carpenter bees act as valuable pollinators. They visit a wide variety of native plants, ornamentals, and some crops, feeding on the sweet liquid nectar from the flowers and collecting pollen to feed to their young. When they do this, they facilitate plant reproduction by carrying pollen from flower to flower. Read more about carpenter bees and their roles as pollinators at

Narrow, tubular flowers present a special challenge for the large species of carpenter bees; the bees are too big to squeeze inside them to get to the nectar and pollen. In these cases, the carpenter bees engage in nectar robbing: they land on the outside of the flowers and use their sharp mouthparts to pierce them and drink the nectar inside. This doesn’t harm the blooms, but it also means that the bees don’t come in contact with the pollen-laden structures inside the flowers, and in these instances, no pollination occurs. Fortunately, large carpenter bees also visit and are able to pollinate wide variety of plants with more accessible flowers, and the smaller species of carpenter bees — unlike their larger cousins — are able to climb into tube-shaped flowers and pollinate them.

I’ve spent many hours in my garden in close proximity to these fascinating insects, observing them without worry. Valley carpenter bees constructed a nest in our redwood arbor many years ago, but we leave them undisturbed, because their limited burrowing doesn’t compromise the structural integrity. It’s been fascinating to watch them fly in and out of the small nest hole and visit nearby perennials, including two of their favorites, autumn sage and foothill penstemon. I’ve been able to photograph the bees up close and to watch them as they hover nearby; I’ve never once been stung, and have been well entertained.

My carpenter bee verdict: Definitely a friend!

To learn more about the highly diverse species of bees in our state, read the book “California Bees & Blooms: A Guide for Gardeners and Naturalists,” published by Heyday Books. For gardening-related questions, call the UC Master Gardener office at 209-953-6112, or visit our website.




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Contemplating climate change and gardening

After several days of scorching temperatures and skies dusky with smoke from local wildfires, it seems an appropriate time to consider how climate change will affect the plant life that gardeners love so dearly.

As our California weather patterns become more unpredictable, it’s inevitable that changes will occur to our local ecosystems. Forests stressed by higher summertime temperatures, more frequent drought conditions, and bark beetle infestations will experience tree die-off at an accelerating rate. Wildfires will become more severe and frequent, burning natural habitat, gardens, and homes. Native plant communities will be forced to migrate to higher elevations as average temperatures rise — or die off if they can’t adapt.  The ability of plants to adapt to changes in precipitation patterns has wide-ranging implications for agriculture, forestry, grazing, the nursery industry, and home gardeners.

California’s water supply, already a critical issue in our naturally arid state, will become an even more pressing issue as our state’s population continues to increase. Mandatory water rationing and water metering for all homes will probably be the wave of the future.

Our family lives in a neighborhood without water meters. We’re extremely conscious about both our interior (home) and exterior (garden) water use, to the point of allowing our never-used front lawn to go mostly brown in summer while we plan a more water-wise landscape. (Sorry, neighbors!) It’s not very attractive at the moment; however, it’s far more discouraging to see other households be so wasteful with precious water. One neighbor runs front yard sprinklers every day on a too-long cycle, leading to wasteful runoff and persistent flooding of a drainage area that leads away from their property. Pay-for-usage water billing (rather than flat-rate charges) will hopefully encourage water conservation and reduce or prevent such misuse.

Weather patterns and water supply are inextricably connected to the health of our gardens and to the productivity of the farming operations that are such a vital part of our county’s economy. The potential effects of climate change are dire, but there is hope. We can all do our part to minimize human impact on our planet and to garden sensibly. Making appropriate adaptations now — such as implementing permanent water conservation measures and switching to water-sensible plants/crops — will help prevent potentially catastrophic consequences in the future.

Here are some ways to make water- and climate-sensible changes to your home landscape:

  • Convert gardens from high-water-use plants to California native plants and low-water-use plants. Consult the WUCOLS IV plant list ( to learn more; it classifies hundreds of plant species by their water needs, from very low to high. (WUCOLS = Water Use Classification of Landscape Species)
  • Water plants and lawns deeply and infrequently (rather than shallowly and often). This encourages their roots to penetrate far into the soil, which in turn makes them more resistant to hot, dry weather.
  • When landscaping, use the principle of “hydrozoning,” or grouping plants together by their water usage. That way, irrigation systems can be adjusted to provide only as much water as those plants need. (Intermixing plants with different water requirements results in overwatering some plants to provide enough water to the thirstiest ones.)
  • Use organic mulches in planting beds to conserve soil moisture and keep plant roots cooler.
  • Use your powers of observation to see what plants look best under stressful conditions. Those that thrive are far better choices that ones that don’t. (For example, after the last severe drought, our local neighborhoods were riddled with dead, dying, or badly suffering redwoods and birch trees. These two species are naturally adapted to moist environments and they require lots of water; therefore, they’re poor choices for the Central Valley.)
  • Check your irrigation system to make sure all sprinklers and emitters are working properly, and fix any leaks. Also, watch for runoff; it’s a sign that water is being applied faster than it can soak into the soil. Adjust your irrigation timer to reduce the length of the watering cycle, or water in a series of shorter cycles.
  • Plant area-appropriate, deciduous shade trees on the south and west sides of your home, if possible. They will help shield your house from the afternoon sun in the summer, keeping it cooler and minimizing air conditioner use. In the winter, the leafless trees will allow the sun to warm your house, reducing the need for heating.

Red buckwheat (Eriogonum grande var. rubescens), one of many durable and beautiful California native plants. It’s an excellent choice for a garden adapted to tough climate conditions. (Kathy Ikeda)

I’m using a portion of my yard as a test plot for low-water-use plants, and I’m being intentionally hard on them. Not counting the initial year of plant establishment, this area gets deep, supplemental watering only a few times each year; I rely mostly on natural rainfall. Despite little water and mostly full-sun conditions, these California native plants are thriving and attractive: California fuchsia, California coffeeberry, red buckwheat, foothill penstemon, sedum autumn joy, deer grass, and two varieties of yarrow. Some other non-native plants—bidens, hybrid soapwort, and cape balsam—are also great successes.

One innovative experiment regarding plants and climate change is now under way at U.C. Santa Cruz. The newly installed Future Garden is a joint science and art project to determine which native plants respond best to the conditions expected to occur with climate change. Read more about it at

In these times of change, let’s all take the time to be conscious of our gardening practices, and to improve them for the benefit of our community and our planet.

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

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Plant it right and don’t plant invasives.

PlantRight is an organization that works to reduce the number of invasive plants sold at nurseries in California. Master Gardeners and other volunteers have helped conduct eight annual surveys to assess how many invasive plants are currently for sale and to encourage nurseries to stop selling such plants. This year, PlantRight is not doing a nursery survey, but instead is concentrating efforts on outreach to landscape professionals (e.g. architects, designers and contractors), and to water districts promoting sustainable landscaping. In the 2017 survey, the rate of nurseries selling invasive plants continued to decline; dropping from 44 percent in 2014 to 29 percent in 2017. For a list of invasives see:

I have battled many invasive, obnoxious plants in my lifetime, so I am always glad to warn others about the hardships that such plants can bring your way. I can say that I have not won a battle with invasive plants. When I bought my farm 42 years ago I inherited some nasty plants along with the beautiful redbuds that caused me to name the place Redbud Farm.

Periwinkle (Vinca major) was growing in several places and it still is today though greatly reduced in abundance. I tried hard to eradicate it, but it has proven very resilient. The roots must be removed or it comes back and I suspect residual seeds too. It has become a major invasive plant in the shade of redwood trees on the north coast where it displaces native understory plants.

Another invasive is Algerian Ivy (Hedera algeriensis) along with others of its ilk who provide good rat habitat. Although I removed it long ago, I keep finding new plants coming up and I am uncertain if this is due to birds dropping seeds or residual seeds from the original plant. It is mostly now a nuisance weed. Birds dropping seeds reminds me of Privet (Ligustrum sp.) whose seeds cause lots of weed trees requiring vigilant weeding, even if you don’t have one in your garden.

Italian Arum (Arum italica) is a woodland shade-loving plant that grows from corms. It resembles a jack-in-the-pulpit with large, arrow-shaped leaves. It grows in the winter and fades away with summer weather but leaves a large seed stalk with orange seeds. It reproduces with seeds along with deeply rooted corms that divide. It naturalizes readily and did so long before I bought the farm, so basically I was stuck with it.

In small locations you can cover the plant with a board and starve the corms for a year or more. This approach is not going to work when it is abundant everywhere. Herbicides do not work and digging out the corms is only practical in small areas. It is difficult to remove all the small corms.

I did remove Arum seed stalks before the seeds were scattered which perhaps helped curb their spreading. Years ago, to develop my step-daughter’s work habits, I paid her 2 cents for every seed stalk pulled and she pulled a few hundred. However, since all parts of the plant are poisonous it is wise to be careful when being in contact with this plant. Would you believe that on-line nurseries will sell you, for only $25 for 5 corms, a bundle of misery and trouble?

Small-leaf spiderwort (Tradescantia fluminensis) is a shade-loving creeping perennial herb that roots at nodes, I thought I had gotten rid of this plant, but it re-emerged to take over all shady understory areas. It smothers everything with vigorous growth and the rooted sections break off easily so removal is difficult. Herbicide such as a 3 percent glyphosate is recommended, but this may not be a solution in circumstances where other plants are present.

Spiderwort is a problem in Florida and in New Zealand where it covers vast areas of understory forests. Recently, I belatedly saw some being sold at a plant sale that I was involved with. I hope none were purchased and next year I will insist we not offer it for sale.

Bermuda buttercup or Buttercup oxalis (Oxalis pes-caprae) is an invasive impossible to eradicate as it grows from bulbs and it makes a bunch of new little bulblets every year. The flower is pretty and blooms in late winter/spring. I had to acquiesce to living with it.

Bermuda buttercup or Buttercup oxalis (Oxalis pes-caprae) is an invasive impossible to eradicate as it grows from bulbs and it makes a bunch of new little bulblets every year. The flower is pretty and blooms in late winter/spring. I had to acquiesce to living with it.

Last week was Invasive Species Action Week in California to awaken the public to the downside of invasive species. I wrote this article before I knew that. For more information see: . Sometimes, the only way to get rid of invasive plants is to sell the farm; so I did. To all gardeners, I wish you happier gardening sans invasive plants, so plant carefully.

If you have a gardening related question, you can contact the UC Master Gardeners at 209-953-6112. More information can be found at:


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Some garden myths to lose

In this new age of ‘Fake News’ when facts are branded as fake and lies are freely airborne, it might be appropriate for gardeners to sort myths from garden facts.

Planting by the moon. I had a gardening friend who swore that you should plant root crops by the dark of the moon. I don’t automatically discount such advice, but finding credible evidence that this is true is non-existent.  True, the moon does affect ocean tides, but its effect on smaller bodies of water is nil and the likelihood that it can affect water movement in plants or germination has never been demonstrated. For more information on this myth see: .

Sunshine focused through raindrops will burn plants. Watering plants in the sun should not be done because droplets of water act like magnifying glasses and will burn holes in the plant’s leaves. If this is so, farmers would encounter huge losses after each daytime rainstorm. Sorry, but there is no way that a drop of water can raise the leaf temperature to a burn.

It is advisable to water gardens in the early morning hours to conserve water and to avoid nurturing moisture-fostering diseases. Plants so watered will dry as the sun shines; unlike plants watered in the evening or at night which will dry off much more slowly thus enhancing disease possibilities.

Copper strips keep slugs and snails away. This is a touted way (though not inexpensive) of keeping these pests from the vegetables in your raised beds. Allegedly, the copper induces an electric charge that deters the pests. Several tests of this shown on YouTube tend to disprove this method. A couple of tests used pre-1981 actual copper pennies and other copper materials in an experiment with snails and slugs. They observed the pests sliding across the copper undeterred. I am not sure that this is a definitive disproof of copper’s deterrence, but it does strongly suggests it doesn’t work. See:

There are ways to curtail snails and slugs and handpicking with a flashlight in the evening, early morning or during or after irrigation/rain will reduce their numbers. Diatomaceous earth and wood ashes piled in rings around plants will protect them as long as the materials are not wet and dry egg shells may work too. Baits using iron phosphate which are harmless to pets and children also can be used. Upturned citrus, shingles or boards with space beneath will provide hiding places that can be checked in the morning for pest disposal.

Use coffee grounds to acidify soil. While coffee grounds are acidic, mixing them into the soil would affect pH very slowly. Fresh coffee grounds tie up nitrogen as they decompose and this can adversely affect plant growth. It is best to use coffee grounds in your compost bin to facilitate the breakdown of leaves or high carbon materials. To acidify soil for acidophilic plants such as azaleas, rhododendrons or blueberries it is best to use soil sulfur as directed on the package.

Newly planted trees should always be staked. Unless the tree is top heavy or in an especially windy location, it does not require staking. Movement is good for young trees as the trunk will grow thicker and stronger when not immobilized by staking. Last winter, I pruned in a small local orchard where young fruit trees had been properly staked as if they were landscape trees. It should never have been done since fruit trees, when properly pruned at planting, need no staking. Unfortunately, they were not properly pruned at planting either. If properly staked, movement should be allowed to help strengthen trunks. Most trees should have stakes removed after 6 months to assure development of strong trunks.

Gravel in the bottom of containers improves drainage. A myth slow to die and one that actually is counterproductive with an increase in the possibility of root rot, not less, with the use of gravel. The water saturates the soil above the gravel as gravity moves it downward, so basically it makes the effective size of your container smaller by moving the saturation pool of water higher in the pot. It is better to use a potting soil that is porous and well drained. Adding perlite or organic matter will increase drainage and soil can be prevented from leaving though the bottom hole by covering it with a piece of screen or landscape cloth.

Adding sugar to the soil will yield sweeter tomatoes. Sugar in tomatoes is the result of photosynthesis. Adding sugar to the soil might feed some soil bacteria, but if you want sweeter tomatoes add sugar after slicing. Some tomatoes are genetically programmed to be sweeter than others and I vote for Early Girl as a sweet one. Happier gardening if you lose the myths.

If you have a gardening related question, you can contact the UC Master Gardeners at 209-953-6112. More information can be found at:

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Protecting Plants from Summer Heat

By Kathy Ikeda

Scorching days have arrived! All but the hardiest of us wilt when outdoor temperatures hit the 90s and 100s, and we seek refuge in air-conditioned places or in water-cooled

Foliage damaged by weather (sunburn).

outdoor areas. Plants don’t have that luxury; they’re literally rooted where they are, and they sometimes need our help to deal with the Central Valley sunlight and heat.

Summer weather can damage plants by stripping them of the moisture they need or by exposing them to more heat or light than they’re adapted to handle. Higher than usual air temperatures, intense light, and overheated or too-dry soil can harm a plant’s leaves, stems, and roots. Wind can further worsen the effects of hot air.

Like humans, plants rely on water partly to cool themselves: we sweat, plants “transpire.” Transpiration is the process by which plants absorb water through their roots, move this water upward through the part of their vascular system called xylem, then lose this water through tiny pores called stomata on the leaf surfaces. The transpiration rate rises in hot temperatures; a plant’s water loss generally doubles with every 18-degree increase.

Plant species vary in the amount of water they need to resist heat and maintain good health (hence their classification as low, medium, or high water use). New plant growth, tender seedlings, fruits and vegetables, and cool-season annuals are particularly susceptible to sun-related damage.

Plants exhibit different levels of heat damage, and it’s important to know the distinction. Wilting is the drooping or shriveling of plant tissues that occurs when they lack sufficient water; it’s reversible if plants are watered in time. (Large-leaved plants will usually wilt a little during peak daytime heat even with adequate water, but will recover when temperatures cool.) Heat stress is when plants begin to suffer irreversible heat-related damage; at this stage, some plants will try to conserve water by dropping leaves or buds. Sunburn (or “leaf scorch”) is when a plant’s leaves or non-woody parts are permanently and severely harmed by excessive heat or sunlight; leaves develop dried brown patches or margins and they eventually wither and fall off. Sunscaldis the cracking, discoloration, and warping of bark that occurs when the trunk or branches of a woody plant get too much sun exposure; the damage is permanent and very harmful since it increases the plant’s disease susceptibility.

A toyon with damaged bark from sunburn after canopy pruning. Photo by Jack Kelly Clark.

Follow these simple guidelines to minimize heat damage:

  • Conserve soil moisture and protect plant roots from excessive heat by covering bare ground with a 2- to 4-inch-thick layer of organic mulch—wood chips, shredded bark, leaves.
  • Don’t place inorganic mulches—sand, pebbles, rocks, shredded rubber—or black-tinted mulch near plants in sunny locations (with the exception of desert-adapted plants), because these materials collect and radiate heat.
  • Follow the principle of “right plant, right place.” Select plants adapted to our Mediterranean climate and choose planting locations with proper exposure. (No shade-loving plants in full sun!)
  • Don’t heavily prune trees and shrubs in summer, because this can suddenly expose tender bark to the sun’s intense rays. It also encourages a flush of heat-sensitive new growth and places additional energy and water demands upon heat-stressed plants.
  • Avoid planting during peak summer heat; this stresses plants and compromises their chances of successful establishment. Delay planting until fall, or (if you must plant this season) wait until a cooler spell, plant in the evening, and water deeply after planting.
  • Keep potted plants well watered and (if possible) move them to shadier locations. Use light-colored or plastic containers, which absorb and transmit less heat than dark-colored containers or those made of ceramic, cement, or metal. Hydrogels (water-retaining polymer granules) can be mixed into potting soil to help hold moisture.
  • Whitewash trunks of young trees to help prevent sunscald. Mix equal parts water and white interior latex paint, then apply it from 1 inch below ground to at least 2 feet above ground.
  • Use strategically placed shade cloth to shelter plants.
  • Ensure that plants receive appropriate and consistent levels of water, and check irrigation systems for proper operation. Do this yourself, or enlist the services of a Qualified Water Efficient Landscaper (

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


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California’s State Soil

We all know California has many state symbols. The grizzly bear flying in the state flag, golden poppies and the valley quail are all symbols that connect you back to our golden state. Did you know that California has a state soil?

What is a State Soil?

A state soil is a soil that has special significance to a particular state. Each state in the United States has selected a state soil, twenty of which have been legislatively established. These “Official State Soils” share the same level of distinction as official state flowers and birds. Also, representative soils have been selected for Puerto Rico and the Virgin Islands. California’s State Soil is the “San Joaquin” soil. The San Joaquin soil was initially documented and officially established in California in 1900 and therefore is the oldest, continuously recognized soil series within the state. It was designated the official state soil of California in 1997.

San Joaquin soil has a distinctive soil horizon (layer) known as a “hardpan” to many people. It is extremely hard and it can be chipped with mechanical means or through use of a pick or very strong, heavy shovel. Typically, San Joaquin soils have a brown to reddish brown surface with a loam texture that has an accumulation of organic matter. It was chosen as the California State Soil because of its interesting soil characteristics, had agricultural significance, had extensive distribution, had a soil name recognizably Californian, and had its typical location in California. California’s central valley has more than half a million acres of San Joaquin soils that can be found along the east side of the San Joaquin and lower Sacramento Valleys as a small but important part of this huge California agricultural base.

A little about soil profiles and textures

Soil Horizons: Soil is made up of distinct layers, called horizons. Each layer has its own characteristics that make it different from all of the other layers. These characteristics play a very important role in what the soil is used for and why it is important.

O HORIZON- This is the top layer of soil that is made up of living and decomposed materials like leaves, plants, and bugs. This layer is very thin and is usually pretty dark.

A HORIZON- This is the layer that we call “topsoil” and it is located just below the O Horizon. This layer is made up of minerals and decomposed organic matter and it is also very dark in color. This is the layer that many plants roots grow in.

B HORIZON- This is the layer that we call “subsoil” and it is located just below the A Horizon. This layer has clay and mineral deposits and less organic materials than the layers above it. This layer is also lighter in color than the layers above it.

C HORIZON- This is the layer that we call “regolith” and it is located just below the B Horizon. This layer is made up of slightly unbroken rock and only a little bit of organic material is found here. Plant roots are not found in this layer.

Soil Textures: Three types of particles are found in soil: sand, silt and clay. Soil texture is classified by the type of particle that makes up the majority of the soil. Each soil type has a distinctive textural feel and holding a sample of your garden soil in your hand may help you determine the type of texture that makes up your garden soil.

Sandy Soil: Sand is the largest of the particles found in soil. It is a sharp-edged material, giving the soil a gritty feel. When wet, it remains course and breaks apart easily. Beach sand is at the extreme end of sandy soils. Sandy soil holds almost no nutrients and does not retain moisture. Plants do not grow well in this type of soil.

Silty Soil:  Silt particles are smooth and smaller than sand particles. When wet, a silty soil feels mud-like; it’s smooth and has a silky texture. It’s rich in nutrients but retains moisture to the point where garden plants are unable to access oxygen. In a silty soil, plants wilt because they can’t breathe.

Clay Soil: Clay is the smallest of the particles and a clay soil will clump and feel sticky when wet. Air flow between particles is limited if not non-existent. When dry, the soil has a dusty feel to it and the surface is hard and dense, making it difficult to work the soil for tilling or digging. Although high in nutrients, clay soil is less than ideal for gardens. Plant roots may not be able to penetrate the dense soils to access nutrients and oxygen.

Loamy Soil: Loam is a combination of all three particles– sand, silt and clay–in nearly-equal proportions. The large sand particles promote drainage and air flow within the soil. The smaller silt particles are rich in nutrients and aid in moisture retention. Clay, also rich in nutrients, balances the poor soil retention of the sand and the excessive moisture of the silt.

Does your garden have the official state soil? Find out the name of the soil in your landscape by visiting the NRCS’s web soil survey page,

If you would like to see all of California’s state symbols from fish to gemstone, visit

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


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An up-close look at pollen (achoo!) By Kathy Ikeda

For many people, pollen is the “p-word”. . . as in, “PLEASE, don’t say that word!” The mere mention of pollen can conjure up runny noses, watery and itchy eyes, and looks of desperation from those with hay fever. Here in the fertile, crop-rich San Joaquin Valley, it’s often said that if you don’t already have allergies, you’ll develop them.

Trees such as oaks, birches, conifers (pines, firs, spruces), and nut crops (walnuts, almonds, pecans) are especially prolific producers of pollen, and they’re ubiquitous in our area. They’re joined by other common pollen-producing plants, including grasses and many of our favorite garden flowers. It’s an allergy sufferer’s nightmare.

Pollen literally means “fine flour” or “mill dust” in Latin. While it’s a health nuisance, it’s also a valuable and necessary evil.

We’re familiar with pollen as that yellowish, powdery-looking stuff that drifts away from trees and other plants in spring and summer, making us miserable as it floats through the air, collects on our cars and homes, and settles in our nostrils. But without pollen, we literally couldn’t survive. The vast majority of plants on Earth depend on pollen for their reproduction, and we in turn depend on plants for food and oxygen.

Pollen is unique to seed-producing plants, which are divided into the flowering plants (Angiosperms) and the cone-bearing plants (Gymnosperms). The pollen-bearing structures of these plants are contained either in the flowers or the cones. More primitive plants such as ferns, fungi, mosses, and horsetails don’t make pollen; instead, they produce spores.

So, what exactly is pollen, anyway?

A clue to pollen’s specific purpose lies in the aforementioned scientific classifications of pollen-producing plants: the suffix –sperm means “seed” in Greek. Pollen is the male vehicle for a seed-forming plant’s sexual reproduction. Each microscopic pollen grain has a hard outer coating that protects the inner contents—two sperm cells and a tube cell—from damage and dehydration.

Plants fall into two categories when it comes to the type of pollination: (1) self-pollinated, or (2) cross-pollinated, where pollen from one plant must transfer to another plant of the same species.

Pollination begins when grains of pollen move from the male part of a plant to the female part of a plant. Pollen transfer can occur in one of two ways: (1) abiotic pollination, where pollen is carried by wind or water (most common in grasses and trees), or (2) the far-more-typical biotic pollination, where a living organism such as a bee, butterfly, moth, wasp, fly, bird, bat, or other animal moves the pollen (most common in non-tree flowering plants).

Once a pollen grain comes in contact with the female part of a plant, it germinates. A pollen tube develops, emerging through a specialized opening in the outer covering then extending toward the structure that holds the egg. The sperm cells then leave the pollen grain and travel through the pollen tube, ending their journey when they reach the egg. Fertilization occurs once the plant’s egg/ovule and sperm cells unite, and that initiates seed development.

Some amazing pollen-related facts about corn: Just one stalk can produce about 18 million pollen grains! The pollen grains land on the ends of the female corn silk; there is one strand of silk attached to each developing kernel. The single-celled pollen tubes that grow from the pollen grains through the silk can be up to a foot long!

Many small members of the animal kingdom depend upon pollen. Honeybees and native bees use protein-rich pollen, either eating it themselves or mixing it with sugary nectar before feeding it to their developing larvae. (Pollen is not used to make honey; honey is regurgitated nectar.) Some beetles—including ladybugs—and many common types of web-weaving spiders also consume pollen as part of their diet.

When seen under a microscope, pollen grains are exquisitely beautiful natural works of art. Their outer coatings are intricately patterned, spiked, or pitted, and different plant species produce their own unique pollen designs. Pollen can be sticky-surfaced or spine-studded so that it’s easily carried on the hair, feathers, or fur of pollinators, or it can be lightweight and aerodynamically crafted to float in a breeze.

False-color scanning electron microscope image of pollen grains from a variety of common plants: sunflower, morning glory, prairie hollyhock, oriental lily, evening primrose and castor bean. (Public domain image from the Dartmouth Electron Microscope Facility)

For more information and a visual treat, read the book Pollen: The Hidden Sexuality of Flowers, or search the Internet for “pollen electron microscopy” to see extraordinary images. And try very hard to appreciate pollen, even as it makes you sneeze.

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


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Deadheading: what it is and why it’s important

What is deadheading? The word sounds somewhat sinister, and if you belong to a certain generation, you might associate the term with those avid fans of a certain 1970s rock band. (Followers of the group The Grateful Dead are known as “Deadheads.”) While the word might lead to amusing confusion, a gardener’s use of the term deadheading has nothing to do with either music or macabre rites.

In the gardening world, deadheading is the practice of removing withered and faded blooms from a plant. There are several reasons why you should make this chore a standard part of garden upkeep.

One of the best reasons to deadhead plants is to improve their appearance. Brown, dry flowers covering a plant tend to look unattractive, and removing them on a regular schedule can tidy up and brighten most landscapes.

Another important reason to deadhead plants is to extend their blooming season and/or to increase the number of flowers they produce in a given year. It all comes down to science. The main purpose of flowers is to attract pollinators, and once that purpose has been served, the pretty blooms’ jobs are done. The plant then diverts its energy into the developing seed heads or seedpods, because seeds are what ensure its ongoing survival. However, if those young seeds are removed, the plant once again channels its energy into the first stage of reproduction. The result: more flowers!

Most annual plants and many perennial plants will continue to bloom (or have a second period of bloom) if deadheaded on a regular basis. Common bedding plants such as marigolds, pansies, and snapdragons benefit from deadheading, as do many favorite perennials, including blanket flowers, coneflowers, cosmos, dahlias, lupines, Shasta daisies, yarrow, and more.

Deadheading is also wise if you have plants that self-sow easily. The word sow means “to plant seed by scattering it on the earth,” and that’s precisely what these types of plants do. Each plant can produce hundreds to thousands of easily germinating seeds, and when the seedpods ripen and dry, they distribute the seeds over a wide area, either by popping open suddenly or with help form the wind. To control the spread of these plants—including beautiful and prolific ones such as California poppies—deadheading throughout the blooming season is recommended to prevent massive re-sprouting the following spring.

Some flowering plants don’t need to be deadheaded, because their flowers drop off on their own once spent. This process, whereby a plant discards a part no longer needed, is called abscission. Plants with flowers that naturally abscise are camellias, impatiens, and rosemary. Other ornamental plants such as fuchsias don’t produce a lot of seeds, and don’t require deadheading.

It’s very easy to deadhead. As a flower fades or drops its petals, snip off its stem just above the first complete set of healthy leaves. On plants with delicate or tender flower stems, this technique can be done without any garden tools; just pinch the stem between your thumb and forefinger. In other instances, where the plants have tough or sturdy stems—especially roses—use a clean pair of bypass pruners with sharp blades to make clean cuts. For plants with a profusion of small flowers, an occasional light shearing is the easiest way to deadhead, but try to avoid cutting off any developing flower buds still left on the plant. Any disease-free trimmings can be composted.

Avoid deadheading when growing plants with decorative seedheads or fruits (such as buckwheats) and plants with seeds that attract birds (such as black-eyed Susan, coreopsis, and sunflowers). Allow these plants to progress through their flowering cycle naturally, and enjoy the transformation from bloom to a different show. Or, if you want to collect and grow plants from seed next year, allow some of the last flowers of the season to reach maturity.

The job of deadheading can seem overwhelming if left undone for weeks at a time. Not many gardeners want to spend valuable time on such a tedious task, snipping dead flowers for hours on end! But if you devote a few minutes every day or two wandering your yard and picking off spent blooms here and there, the seemingly daunting task can become a pleasure. What better way to become intimately familiar with your garden, enjoy some fresh air and natural beauty on a daily basis, and get a healthy dose of vitamin D with a little time in the sunlight? Both you and your garden will benefit.

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


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    Lee Miller is a University of Delaware graduate and retired fisheries biologist, he gardens on 10 acres and makes wine each year with the help of a cadre of friends. However, his first love is gardening and he grows various fruit trees, heirloom ... Read Full

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