Be sure to put on your sunscreen, wear a hat, and keep those tools clean and sharp as you enjoy the garden in June!

May is one of the busiest months in the garden. Temperatures have warmed enough for us to begin planting in earnest. Weeds, pests, and beneficial insects are out in force. And it's gorgeous outside!                                                                                                           


Aerate the soil                                                                                                          

Our San Francisco Bay Area soil is heavy clay. This means it can hold on to lots of water and nutrients, but it can be difficult for roots, earthworms, and soil microorganisms. You can hire a professional aerator to come in with their heavy equipment to punch plugs out of your soil. While the machine creates its own soil compaction, the plugs really do make a big difference in soil health. Or, you can do what I do, which is to contact your local tree trimmer and ask for a load of tree trimmings. It won’t be the pretty bagged variety, but it will contain chipped twigs, leaves, stems and branches that can be spread on top of the soil as a mulch that will profoundly improve your soil structure. In 2012, when we bought our home, the soil was more like concrete. Now, thanks to mulches of tree trimmings, my soil is rich and black, loose, and filled with earthworms and beneficial microorganisms. For free.


Bees

Bees are very active in May. There is simply so much pollen and nectar to collect! Sometimes, a honey bee colony may swarm. If you see a swarm, don’t panic. As in any other time when working around bees, remain calm, move gently, and give them their space. Contact your local Bee Guild or  Master Gardeners to have swarms removed.


Bulbs and other flowers

If flowering bulbs were looking crowded during the recent bloom time, delay digging them up to separate until after all the foliage is completely dry. Bulbs pull important nutrients from these leaves to help start up again next spring. Bulbs that are dug up and separated can be replanted in a new location, gifted to friends, or stored in a cool, dry, dark location until fall. If you want fall blooms, plant now.


Container plants

They are countless varieties of plants that perform well in containers. Do them all a favor in May and get them off that soon-to-be hot concrete patio. Creating even the smallest space under container plants can reduce the roasting effect, which means they will need less water. Speaking of water, warmer temperatures mean container plants will start drying out more quickly. Water as needed.


Deadheading

Many flowers are in full bloom in May. To encourage plants to continue creating blooms, remove spent flowers as soon as they are seen. This also reduces habitat for many pests and diseases. Pinch back borage, petunias, and fuchsias to prevent plants from becoming top heavy.


Fireblight

May is the time fireblight shows itself in the Bay Area. Fireblight is a bacterial disease that makes plants look as though they had been damaged by fire. It attacks apples, pear and quince, most often, but can also infect ornamentals, such as toyon and pyracantha. Very often, the growing tip folds over into a shepherd’s crook shape. Fireblight can kill a mature tree, so complete removal of any diseased tissue is critical. Dip clippers into a 1 part bleach, 9 parts water solution between each cut to prevent reinfection. The final cut should be 8-12 inches below the diseased area.


Fruit trees

May should be the time when fruit trees are covered with immature fruits. Thin those fruits now or regret it later. Too much fruit in one place means none of them taste as good as they might have. It also creates habitat for pests and disease. Apples should be thinned to no more than 3 fruits to a cluster, or one fruit for every 6 inches of branch. Apricots and other stone fruits need 4-6” between fruits for optimal growth, flavor, and sweetness. Also, be sure to check apples for codling moth damage.


Lawns

If you still have a lawn, be sure to water it as early in the morning as possible. That way, the water isn’t lost to evaporation and the grass has time to dry out during the day, reducing the chance of fungal diseases. For the most part, I use water from my washing machine to water my lawn and it has been working very well. Check the lawn for weeds such as spurge, burclover, and whatever happens to invade your neighborhood. When mowing, set the blade height as high as you are comfortable with in summer. Taller grass shades the soil. This reduces evaporation and it makes the soil more comfortable for valuable  earthworms and microbes.


Mulch and compost

Compost and mulch are two of the best things to add to any landscape. They add valuable nutrients to the soil, improve soil structure, and stabilize soil temperature. In our heavy clay soil, mulch prevents the baked concrete look we have come to expect in summer. [An important note about soil additives - while it may sound right to add sand to clay soil, to reduce compaction, it ends up creating concrete. Don’t do it!]


Slugs & snails

Slugs and snails can devastate young May seedlings. Applying non-toxic slug and snail bait lightly around new planting areas can save the crop. While there are more effective baits, those made with iron phosphate are not toxic to pets and wildlife and I have found they work well enough.


Soil test

Before you start applying fertilizers and fungicides, collect a soil sample and send it out to a lab. [I use the UMass lab, but there are many to choose from]. The information provided in soil test results is invaluable. More often than not, your soil does not need more of all the nutrients found in a bag of fertilizer. It may only need some, or, in my case, it only needed iron because it held an excess of everything else. Simply adding more fertilizer can create nutrient imbalances that make it difficult for plants to absorb what they need. Get a soil test. It’s worth it.


​Start planting!

This is the most welcome news of the season in the Bay Area. Nearly all summer growing plants (tomatoes, cucumbers, melons, squash, beans, corn, and peppers) can be put in the ground in May. If you are using transplants, be sure harden them off gradually or they may lose much of their vigor and productivity. Hardening-off simply means placing them outdoors in a protected location for a few hours. Slowly increase the time over a couple of weeks. Be sure to stake tomato plants now, while they are small. This can be done in tandem with quarantining new plants. And add straw under melon, squash, and strawberry plants to reduce fungal infection.


Verticillium wilt

If verticillium wilt occurred last year, it is important to plant members of the nightshade family (tomatoes, potatoes, peppers and eggplant) someplace else. Verticillium wilt is a fungal disease that shows as yellowing older leaves, at first. Then, as the disease spreads, wilting occurs. Young plants nearly always die. Since the fungal spores can remain in the soil for 10-15 years, crop rotation is the best prevention.


Water

California’s drought is continuing, despite the fair bit of rain we have received so far. The truth is,  the Golden State has always been drought-prone and we would be wise to learn to live accordingly. When water restrictions were first implemented, I vowed to take meaningful steps to reduce our water consumption. As a result, we now use only 25% of the water we used to use! Surprisingly, my garden has not suffered and neither have we. These steps can help you conserve water while still caring for the garden:

• Collect water from the bath or shower as it warms and use it to water plants.
• Collect water from boiling pasta and vegetables and use it to water plants.
• Inspect spigots, hoses, sprinkler and drip irrigation systems for leaks.
• Water early in the morning, and water deeply and less frequently.
• When adding new plants, pick varieties that are suited to the local microclimate.
• Avoid urban drool by setting sprinklers to go through a series of pulses. Start with just a few minutes to allow hydrophobic soil to absorb the water, rather than run off.
• Apply organic mulch or wood chips everywhere.
• Turn off faucets while washing hands, brushing teeth, or shaving.
• Use only the minimal amount of fertilizer. Excess fertilizer forces plants to grow faster than they can maintain without a significant increase in water use. Without a soil test from a reputable lab, you don't know if fertilizers are needed.
• Be aware that the drought brings more wildlife into yards as they search for food and water. You may want to provide a water source, such as a birdbath, but be sure to not create a mosquito breeding ground.

Weeds

Just as young garden plants are really kicking it into high gear in May, so are the weeds. Take my word for it, pulling them while they are small, and before the soil is baked, is much easier than later. Weeds take precious water and nutrients from garden plants. In most cases, the sooner they are gone, the better.


So, put on the hat and sunscreen and get out there in that May garden!

April is a busy month in California gardens. With scorching summers on a not-too-distant horizon, flowers, weeds, and every other living thing are striding toward sunlight. Cool nights may hold this rampant growth in check for another week or two, but most gardeners have plenty of April garden tasks to keep them occupied.


Plum bud gall mite

As of January 2019, we have a new pest in northern California. Be on the lookout for abnormal growths, or galls, on almond, apricot, plum, pluot, and many other fruit and nut trees. These tiny eriophyid mites are only 1/100th of an inch long. If you have a 20x hand lens, you may be able to see them. They can be a translucent yellow, pink, white, or purple, with two pairs of legs up near the head. You are more likely to see galls on new shoots and fruit spurs that plants produce in response to these invaders. This new pest threatens tens of thousands of fruit and nut trees in California. If you happen to see this new pest on your trees, please contact your County Extension Office right away.


Tree Trunk Painting

If you didn’t whitewash your tree trunks (and exposed branches) in March, there is still time to provide this valuable sun protection. Trunks and branches that get too much sun exposure can be damaged, causing the bark to split and peel. This provides pests and diseases with easy access to your trees’ inner workings. A simple mixture of half water and half white interior latex paint is all you need to protect your trees from sunburn this summer.


Sticky barriers

This is also a good time to replace last year's sticky barriers. The protection from crawling insects cannot be overstated. Sticky barriers block those crawlers (and slugs and snails) from getting up into your fruit and nut trees. This is especially helpful when it comes to ants, which will protect and farm aphids. Over time, the goo dries, making it ineffective. Also, the tape tends to pull away from the trunk, creating an easy trail for pests. Gently remove the old tape, inspect the trunk, and apply a fresh sticky barrier.

 
Codling moth

Codling moth larvae can devastate apple, plum, pear, and walnut crops. The larvae pierce the fruit and burrow into its core, where it then feeds on the fruit, making it inedible. On apples, look for tiny dimples with a small hole in the center. These holes are usually filled with frass (bug poop). Trees should be monitored every week for signs of infestation. Infested fruit should be removed and discarded, to break the codling moth life cycle. Pheromone traps can be hung in isolated trees, but you need to understand that these traps attract codling moths to the tree. The traps are really a population monitoring device, not a control measure. Fruit can be bagged for protection, but this is a very labor intensive method. Kaolin clay application is an excellent organic control method. Heavy infestations may require the use of pesticides on the moths, before fruit is affected. 

Deadheading

As flowers begin blooming, you can increase production by removing spent blooms. Take a look at buds further down the stem and clip just above a bud that points in the direction you want the new growth to go. Deadheading can help the plant structurally and allow for good airflow, as well as stimulate new flower development.

Thinning

As difficult as it may be for gardeners to thin out fruit and young plants, it really is necessary for the optimal growth of remaining plants. April is the time to thin fruit on fruit trees, such as apricots, peaches, apples, pears, nectarines, and plums. Crowded fruit doesn’t get as big as it could and it encourages fungal diseases. Close-quartered fruit also provides great hiding places for pests. The best fruit grows from strong flower buds in full sunlight. The basic rule of thumb for thinning fruit is to leave one fruit per spur, with fruit 4-6” apart. Apricots, nectarines and peaches are normally thinned when the fruit is 1/2-3/4” in diameter. Nut trees do not need to be thinned. Seedling plants should also be thinned according to seed packet or other reputable information. This allows each plant to reach its full potential and it reduces problems with pests and diseases.


Fungal diseases

Spring rains bring moisture that can cause many fungal diseases. Anthracnose, brown spot, powdery mildew, sooty mold, and verticillium wilt should all be watched for and treated. Many of these conditions can be avoided with pruning that allows good air flow and irrigation that does not come from overhead. Overhead watering splashes millions of fungal spores onto uninfected plants, spreading the disease (plus, it wastes water through evaporation).


Irrigation & greywater

As temperatures rise, irrigation becomes more important. Container plants will begin to dry out and need to be checked every day. If the irrigation system wasn’t inspected in March, be sure to do it now. Greywater, from sinks, washing machines, and rain barrels can be used to irrigate ornamentals and lawns. I use water collected from the shower, as it heats up,  to water edibles.


Mulch

To add nutrients, reduce weeds, and to help retain moisture, nothing beats mulch. Wood chips and aged compost both make excellent mulch. You can request free wood chips from local tree trimmers. To stop weeds from growing, the mulch should be 4 to 12” think. I used to recommend a layer of cardboard or newspaper. That was until I learned that cardboard attracts termites and voles, and slows gas and water exchanges. Be sure to keep mulch at least 8” away from tree and shrub trunks, to avoid fungal diseases, such as crown rot.


Oranges

If you have Navel orange trees, the crop will be ripening in April. Oranges left on the tree too long will dry out and become inedible. Instead, harvest the entire crop by the end of the month and you can make my new favorites, Cardamom Orange Marmalade, Orange Cumin Chutney and Spiced Oranges. Once canned, these delicious condiments make lovely gifts. You’ll want to be sure to save plenty for yourself - it’s that good! Valencia oranges will ripen during the summer and they make excellent juice. April is a good time to add nitrogen for orange trees. One-year old trees will need 1/10 of a pound of nitrogen, while mature trees need approximately 1-1/2 pounds. These amounts should be divided into three different feedings in April, June and August. Blood meal is an excellent source of nitrogen, without all the fillers.

QUARANTINE WARNING: MOST OF SANTA CLARA COUNTY IS UNDER QUARANTINE FOR CITRUS, DUE TO THE ASIAN CITRUS PSYLLID. CHECK THIS MAP TO SEE IF YOU ARE AFFECTED. ALSO, BE ON THE LOOKOUT FOR ORIENTAL FRUIT FLIES. IF EITHER PEST IS SEEN, PLEASE CALL THE PEST HOTLINE AT 1-800-491-1899.


Perennial edibles

Fennel, arugula, rhubarb, and asparagus provide many years of food production and April is a good time to plant. Fennel and rhubarb will take up a good amount of space, so be sure to keep mature sizes in mind. 


Salad planting

Temperatures have finally reached the point when gardeners can plant most herbs, leafy greens, and other salad ingredients. Lettuce, spinach, bok choy, basil, parsley, cilantro and radishes can be planted every couple of weeks (succession planting) for a continuous harvest until temperatures get too hot.


Vegetable planting

Most vegetable crops can be planted in April, here in the Bay Area. Potatoes, bush and pole beans, corn, cucumber, summer and winter squash, and tomato seeds put in the soil now will begin their journey toward fruitfulness. Be sure to read packet directions for planting depth, spacing, and sun requirements for the best results.

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Weeding

One of the most important April garden tasks is to get rid of those weeds. Since they can go to seed faster than everything else in the garden, removing them out now will save you countless hours of work later on, in the summer.

Autumn leaves

As trees drop their leaves, think before you rake. Fallen leaves make excellent compost or mulch but they will interfere with your lawn, if you still have one. Leaves should be removed from lawns and concrete (due to staining), but there is no reason that I know of for removing leaves from anywhere else. From my point of view, fallen leaves are plant foods and soil amendments that have been around a lot longer than us. The only exception might be leaves that are exposed to a lot of car exhaust. You might not want to add those amendments to your soil.


Rain barrels

If you have rain barrels in place, be sure to check all the connections and spigots before the rain starts. If you haven't yet, this is an excellent time to take a power washer or your garden hose to the interior of your rain barrels. Throughout the year, various microorganisms can take up housekeeping in these moist, protected areas, and some of those critters can cause illness in pets, plants, and humans.


Sooty mold fungus

Remember those aphids, mealybugs, whitefly and scale bugs that tormented your garden all summer? Well, they left behind copious amounts of honeydew that create the perfect growth medium for mold. Sooty mold is common in the Bay Area and is easy to recognize as black smudges on leaves and fruit. While the mold can be washed off food and eaten safely, it can be devastating to host plants. The mold actually blocks sunlight from entering the leaves, slowing or even halting photosynthesis. Ants carry the disease, so slowing ant traffic can be a big help. The easiest way to block ants is to wrap tape around the trunks of trees and apply sticky barriers to the tape. Also, trim branches away from buildings, fences and other plants, and use ant bait. While you are at it, November is also the perfect time to caulk your home against winter invaders.


​Fire safety

Fires can be devastating. Change the batteries in your smoke detector, have your chimney and/or furnace inspected, and look at your landscape with an eye for fire safe gardening.

Autumn pests

Cooler temperatures may reduce the number of pests in your garden and landscape, but imported cabbageworms and Harlequin bugs will be doing their very best to wreck your cole crops. Cabbages, cauliflower, and broccoli leaves should be checked frequently for cabbage moth eggs (tiny clear-ish white flecks on the underside of leaves), small (and some not-so small!) green cabbageworms, and clusters of drum-shaped Harlequin bug eggs. These eggs can simply be brushed off and the hatched larva will generally be unable to find their way back to the host plant. You can also use row covers, once you are absolutely certain that you have removed all the eggs. [Check every few days anyway, just in case.]


Frost

It may be difficult to imagine frost in California, but Santa Clara Valley's first frost date is November 15th. Frost dates are statistical averages over time. They are not written in stone. I can tell you, speaking from experience, it is far easier and more comfortable for you to prepare your plants' frost protection against winter sunscald and frost cracks before it is needed. Old bedsheets, row covers, and even umbrellas can provide all the protection that's needed, just be sure to make it so that the fabric does not actually touch the plant.

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Mulch

You can stabilize soil temperatures, reduce weeds, and slowly add nutrients to your soil with mulch. You can buy different sizes, colors, and materials, or you can contact local tree trimming companies for free mulch. Wherever it comes from, be sure that it is disease-free and that it won't float away when the rains comes.

Harvesting the fruits of all that labor and preparing for winter keep the September gardener busy. Deadheading, clearing away debris, and composting spent annuals all help to prevent future problems with pests and diseases.
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Apples
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Many apple varieties are ready for harvest (assuming the birds have left any uneaten). Other apple varieties will need some colder weather to sweeten. If you notice small brown, corky areas under the skin, it is called bitter pit. Bitter pit, like blossom end rot in tomatoes, is caused by a calcium deficiency early in the spring. In this case, however, the condition can be treated on future crops by spraying the leaves with calcium nitrate just after bloom and again one or two months later. Use one tablespoon per gallon of water.


Carrots

Carrots prefer loose soil, but shorter varieties perform well enough in our heavy clay. The addition of compost can help aerate the soil and provide valuable nutrients. Carrots should be planted no more than 1/2” deep and plants should be thinned to 3” apart, to avoid forking and twisting. Water regularly but allow some drying to prevent cracking. Successive plantings provides an ongoing harvest. Carrots can be planted between landscape perennials for productive use of space.


Cover crops

Areas of the garden that will be left bare over the winter are better planted with cover crops. Cover crops help maintain important soil microorganisms that will, in turn, support your spring and summer crops next year. Fava beans are an excellent choice in the Bay Area.


Leafcutter bees

If rose leaves are exhibiting neat round or oval holes in them, it is probably the beneficial leaf cutter bee and should be ignored. The sections of leaf are used to line brood cells, which are also filled with nectar and pollen.
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Mosaic virus

Squash and cucumber plants are susceptible to a disease carried by aphids and cucumber beetles. Mosaic virus causes leaves to become mottled and stunts plant growth. Fruit may become white. Diseased plants should be removed and put in the trash. Do not add to the compost pile.


Powdery mildew

As nights become cooler, it is common for powdery mildew to strike. Affected leaves should be removed and thrown in the trash, and overhead watering should be avoided.


Rats

Gnawed fruit, empty snail shells, and tiny black pellets are all signs of roof rats. These pests can infiltrate your attic, crawl space, garage, storage shed, and trees. Rat traps are an excellent way to remove resident rats. Keeping pet and livestock food sealed up and harvesting crops as soon as possible will help make your yard less desirable to the local rat population. Since rats can carry serious diseases and damage electrical wiring, it is worth the effort to get rid of rats.


Spider mites

If leaf stippling and tiny webs are seen, spider mites are probably the reason. Spider mites prefer dusty conditions, so spraying infested plants with the hose can help. Using broad spectrum pesticides is not recommended because they will kill the spider mites’ natural predators. Heavy spider mite infestations can be treated with insecticidal soap or horticultural oil.


Tomatoes

Any yellow flowers produced by your tomatoes now will not have time to mature before temperatures cause fruit to turn mealy before maturing. Instead, remove those flowers to encourage plants to put all their energy into any fruit that is already on the vine.


Vegetables

September is the time to plant many winter crops, including artichoke, arugula, beets, bok choy, cabbage, carrots, cauliflower, chard, cilantro, collards, dill, fennel, kale, leeks, parsnips, peas, radishes, rutabagas, spinach, and turnips.


Enjoy the fruits of your labor!

July in California can get too hot to spend much time outside. Early morning and late evening make working in the garden far more comfortable, but leave most of the heavy work to the plants as they produce leaves, stems, and fruit in response to all that sunlight. The best things you can do for your garden in July is irrigate properly and monitor plants for pests and diseases.


Monitoring for pests and diseases

You know what they say about an ounce of prevention. Well, here are a few helpful July ideas that work to prevent problems in the garden before they have a chance to get started:
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• Check on the undersides of leaves for pest damage, fungal growth, frass, or webbing.
• Inspect leaves for curling, galls, stippling, or wilting that can be caused by water stress, thrips, aphids, or other pests. Common summer pests include cucumber beetles, stinkbugs, squash bugs, mites, crickets and grasshoppers, and hornworm. Of course, we’re never done battling earwigs, aphids, or slugs and snails!
• Use trellises and other supports to lift melons, squash, and other produce off the ground to keep them away from pests and fungi.
• Eliminate all standing water, no matter how small. Mosquitoes can be a serious health hazard.
• Keep the compost pile decomposing properly with plenty of moisture. It should be as wet as a wrung out sponge.
• Avoid fertilizing in summer. New growth uses a lot of water and can stress a marginally healthy plant.
• Use netting, row covers, and chicken wire to help protect plants against damage by squirrels, rats, birds, and voles.
• Be sure to harvest the fruits of your labors as soon as they are ready. Allowing ripe produce to sit only invites pests and disease, and it takes away from the delicious freshness you were looking forward to when you started your garden in the first place!

Trees

It’s all too easy to forget about the trees in your landscape, but scorching summer heat and an extended drought can be devastating. Trees are a big investment of time and space, so be sure to include them in your watering plan. The only exception is our CA live oaks - they are accustomed to hot, dry summers and watering them only makes them susceptible to disease.


Irrigation

There is no fixed magic formula for watering plants in the garden. There are simply too many variables, such as plant variety and age, soil type, fertilization practices, sun and wind exposure, overall plant health and life stage - you get the idea. The best way to assure that your garden plants are getting the water they need is to learn as much as you can about the specific varieties and their water needs. This information will help you to provide them with the growing conditions they need. Be sure to water tomatoes, peppers, eggplant, and squash consistently, to avoid blossom end rot.


Container plants

During summer, container plants may need a drink practically every day. Just be sure to avoid overwatering - a drowning plant looks an awful lot like a plant that’s dying of thirst. An inexpensive moisture meter ($10-15) can help prevent irrigation errors. Also, be sure to get those containers up off the concrete. Even the smallest air space underneath can significantly reduce temperatures for potted plants.


Lawn

If you still have a lawn, be sure to raise the blade on your mower. Taller grass shades the ground, reducing water loss and stabilizing soil temperatures. By the end of July, your lawn will probably be brown, and that’s okay. Keep watering it. The root system will stay alive, and green shoots will come back in the fall after temperatures go down. [I use water from my washing machine with no negative results and my lawn stays green far longer.]


Basil and other heat lovers

It is finally warm enough for crops such as basil, melons, eggplant, and peppers to really thrive. These are some of my favorite plants. You can train melons up a trellis or ladder, and you can never have too much basil. If you have more than you can use fresh, simply whip up a batch of pesto and throw it in the freezer. Come January, you’ll be glad you did!


Mulch and side dressings

Summer is an excellent time to mulch unused garden areas. As it breaks down, the organic material will improve soil structure and add valuable plant nutrients. This is particularly helpful if you have compacted soil. Until it does break down, mulch stabilizes soil temperatures, reduces weed competition, and helps soil retain water. In the same way, side dressing the plants in your garden or foodscape with aged compost is a trouble-free way to add nutrients to growing plants without applying chemical fertilizers.


As you lounge in the shade with an iced tea, remember that July is an excellent time to consider what cool season crops can be added in fall!