Monthly tips are categorized by: To-Dos, What to Plant, or Pests and Diseases. Scroll through the list to see items in each category.
To extend your basil harvest, pinch the flowers off the tips as soon as they start to develop to prevent the plant from developing seeds. When selecting leaves for eating, choose young leaves at the top of the plant and cut the stem at that point. This will help the plant branch out as it produces new growth.- June, July
- Clean Up Fallen Fruit
Pick up fallen fruit daily to prevent attracting critters or diseases. If your fruit is being eaten at night then rats are the likely culprit, if it's during the day it may be squirrels. Holes, rather than bites, are made by birds. In addition to harvesting regularly, ripening fruit can be protected with a netting fine enough to exclude birds and small animals- July, August
Composting is a good way to repurpose yard and kitchen waste, and it provides a free method to feed plants and improve soil structure. If you are unsure about how to begin composting, take a look at this simple how-to compost page. You can also go to the UCCE Composting Education Program website to learn more about free two-hour classes offered throughout the county.
As the weather warms up, compost piles dry out faster. Keep compost piles as damp as a wrung-out sponge to keep organisms alive and working on decomposing yard waste. Turning the pile to incorporate more oxygen also supports life in the compost pile.- January, February, March, April, May, June, July, August, September, October, November, December
Deadheading means removing spent blossoms from your plants. Not all plants need deadheading, but if the flowers stay on the plant and become unattractive (think roses, dahlias, marigolds, coneflowers, geraniums and many more), then consider a little pruning. The technique varies by plant; some spent flowers can be snapped off by hand (dahlias), others are better done with hand pruners (roses), and some can be sheared off all together (lavender). You'll not only make the plant look better, you'll stimulate additional blooming for plants that have a long blooming season.- April, May, June, July, August, September
- Deep Watering Trees
Even if a tree gets watered every time the lawn does, it needs deep watering twice during the summer. Use a soaker or drip hose around the tree at the drip line and let it slowly drip for 2 to 3 hours. A mature ornamental tree or street tree may not need any water. Mature fruit trees should watered by filling a watering basin around the tree every three or four weeks. Young fruit trees need watering every two weeks. Don't let lawn sprinklers hit tree trunks as this may cause crown rot and damage the tree.- July, August, September
- Drip Irrigation
Consider various forms of irrigation conversion! Irrigation systems, especially drip and micro-sprinklers, have drastically improved over the last few years. For example, there are kits that convert pop-up sprinkler heads to low-flow systems. The conversion kits include a pressure regulator to control changes in pressure and a filter to improve water quality. Water usage is reduced through better water management, control of distribution and less loss from evaporation. Other advantages include :
- Water is placed more accurately and efficiently in the root zone, it is applied at a slow rate that reduces loss from runoff.
- Dry soil between plants allows you to work in the garden between irrigating.
The key to success is watering long enough to supply adequate water to the root zone. Inappropriate watering commonly damages landscape plants. As with any irrigation system, they are efficient only when soil around the plants being irrigated is regularly monitored for proper moisture levels (Reference: UC Pest Note Poor Water Management, Poor Drainage).- March, April, May, June, July, August, September
- Eliminating Perennial Weeds
To control perennial weeds, repeatedly cultivate soil in summer and, when possible, keep the soil completely dry for several months to dehydrate weed stems, rhizomes, or tubers.- July
- Fertilizing Ornamentals During Drought
One way to manage plants during drought is to reduce the amount of fertilizer used. While plants need nutrients to survive and be healthy, excess fertilizer promotes additional growth, which then demands more water.- May, June, July, August
- Fresh Fruits and Vegetables Without a Garden!
If you like the freshest possible produce but don't have the space or time to grow your own, find a certified Farmers Market or a farm selling directly to consumers. The County of Santa Clara website has a Farmers Market page with links to certified Farmers Markets and the Country Crossroads map shows where you can buy more than 100 commodities directly the farm source.- June, July, August, September
- Fruit Tree Harvest
If you have fruit trees that are ready to pick and more fruit than your family can use, please contact Village Harvest. Village Harvest is a non-profit volunteer organization in the greater San Francisco Bay Area that harvests fruit from backyards and small orchards, then passes it along to local food agencies to feed the hungry. They also provide education on fruit tree care, harvesting, and food preservation.- July
- Garden Sanitation
Remove spent blossoms, fruit, and other plant parts as your plants finish producing. Dead and decaying plant parts can attract pests and give them safe places to breed. If pests are given a nice place to spend the winter, their populations are likely to be much higher next year.- July, August, September
- Garden Tools
When you use garden tools be sure to clean them before you put them away especially if you are cutting diseased plant materials. Cooler and wetter conditions make it even more important to wipe mud and sap off metal surfaces before storing them. Our Tool Care Tips provide more information.- January, April, July, October
- Garlic Harvesting
If you can't smell the garlic from your home in the mornings like so many Valley residents can, then all you need to do is check the Gilroy Garlic Festival dates to know it's harvest time! I use the "stop watering Mother's Day, harvest on Father's Day" advice to remind myself, but anytime late June or early July you should start looking closely at your plants. Because it's an underground harvest, timing is more important; harvest too early and the shelf life diminishes; harvest too late and the garlic can be overripe. Generally, you'd like to see the lower leaves brown and some green still on the upper leaves. After digging up, put the garlic out of direct sunlight in a place with good air circulation. The University of California Vegetable Research Center has additional general Information on Garlic (including recommended varieties and problem diagnosis info). See UC Pest Note on Onions and Garlic for diseases and pests that affect garlic.
When harvesting save the biggest bulbs of garlic. If you save the biggest of the bulbs, you can plant those cloves again next year increasing your odds for a great crop. The UC Master Gardeners of Napa County have more information about Growing Garlic.- June, July
- Hand Pollinating Squash
Squash plants have male and female flowers on the same plant. The male flowers grow on stalks and the females are attached to the end of the fruit. If the squash grows a few inches and then starts to die, it is not getting pollinated. You can do it yourself by taking the center (anther) of the male flower and rubbing it on the center (stigma) of the female, or transferring the pollen with a toothbrush or q-tip. It is important to use only freshly opened flowers. They open early in the morning and are receptive for only 1 day. Or if you are fortunate a bee will do it for you.
Male blossom on the left, female on the right.- July, August
- How to Tell if Fruits and Vegetables Are Ready to Pick
The UC Davis Postharvest Technology website was designed for commercial growers, but the information on how to tell When Fruits and Vegetables are Mature is handy for home gardeners as well. There's also information about how to Store Fruits and Vegetables for Better Taste.- July, August, September
- Irrigation and Graywater
As temperatures rise, irrigation becomes more important. Container plants will begin to dry out and need to be checked every few days. Inspect irrigation systems for leaks, clogged drip emitters, misaligned sprinkler heads, and other problems which could waste water. Make sure the water is going to the root zones of the plants.
Things to consider:
Use a smart irrigation controller. These help adjust watering based on local conditions. Learn more about smart controllers.
Collect water from the shower as it heats up and use it to water any plants.
Use graywater from garage sinks and washing machines to water ornamentals and lawns. UC has a publication titled Use of Graywater in Urban Landscapes in California.- April, May, June, July, August
- Keep Up With Your Vegetable Harvest
The middle of summer is a particularly busy time of year for vegetable gardeners. It can be a challenge to keep up with harvesting—beans can become swollen and tough and zucchinis can become baseball bats! It's particularly important to keep up with plants such as beans because the production of mature seeds (inside the pod) signals the plant to stop producing. Tomatoes can split and rot on the vine in exceptionally hot weather.- July, August
- Lawn Care
If you have a lawn, be sure to water it as early in the morning as possible to avoid evaporation. This also helps reduce fungal diseases by giving grass time to dry out during the day. Poor watering practices are the main reason for dead and dying areas in lawns and a common source of urban runoff.
Check lawns for weeds such as spurge, burr clover, and whatever happens to invade your neighborhood. When mowing in the summer, set the blade height as high as you are comfortable with—taller grass shades the soil, reducing evaporation and protecting valuable earthworms in the soil. Use the UC Guide to Healthy Lawns to learn more about mowing, irrigating, fertilizing, detaching and aerating. Better yet, take advantage of the County's Lawn Replacement Program!- May, June, July, August, September
By this time the vines have spread out and there are flowers everywhere. A foliar spray of a water-soluble fertilizer will give them a boost now. Keep the water flowing as they are one of the thirstiest plants you can grow. You can set young melons on the top of inverted cans (coffee cans, tuna cans, etc.) to warm them faster and more evenly. Punch a hole in the bottom of the can so water won't puddle and rot the melon. Melons will begin ripening in August. How will you know when it's ripe? The background color behind the netting will turn from green to tan. The stem will slip right off with just a light touch. Last but not least. let your nose tell you if it's ripe. Smell the stem end; it should have a wonderful melon aroma. The color and smell test also works well in the grocery store.- July
- Mulch - a Gardener's Best Friend
Mulching around your plants has many benefits. It holds in moisture by reducing evaporation from the soil, keeps weed seeds from being able to germinate, and moderates the temperature of the soil so that it doesn't vary as much with direct sun and changes in air temperature. Mulching can cool the soil for plants like blueberries and it will help hold some heat in for summer vegetables as the air gets cooler.
Mulch will guard against soil erosion when the rains start. Organic mulch such as wood chips or bark will slowly break down and improve your soil over time.
It is recommended to keep mulch six inches away from trunks and twelve inches away from buildings. If you are confused about the difference between compost and mulch, then UCCE's Soil Management - Compost versus Mulch Comparison will help.
Many local tree trimming companies are happy to deliver free wood trimmings that can excellent mulch - just be sure that the trimmings are disease- and palm- and eucalyptus- free. This can be hard to guarantee. Straw (not hay) from the local feed store can also be inexpensive, effective mulch.- May, June, July, August, September
- Prioritizing Plants for Watering
As our drought continues, you may have to choose which plants in your landscape will receive the limited water. California Natives and other drought tolerant plants can go long periods without water. Mature trees have deeper roots to find water, but can become hazards if they get too dry and start to drop limbs. Annuals and easily-replaced plants would be the lowest priority. Your Landscape During Drought has more information.- July
- Protecting Fruit
If you don't eat your fruit the minute before it's ripe, birds or squirrels will. Once you see signs of damage, either pick the fruit, or find a way to protect it. For example using netting or paper bags. Pick up any fallen fruit as so not to attract rats or other less visible pathogens.- July
- Pruning Roses to Minimize Disease
A chemical-free way to keep roses healthy and minimize disease associated with foggy summer mornings is to prune to improve air circulation. Think of your rose bushes as large vases, with open centers. Good air circulation allows the morning dew to dry, and helps prevent rust and powdery mildew. UCCE's Center for Landscape and Urban Horticulture has more info about the Fundamentals of Pruning Roses. The UC Pest Note on Roses has more about general cultural practices and weed control.- May, June, July, August
- Save Water and Make Your Plants Happier
After your vegetable garden is well established, it's better to water thoroughly once a week rather than giving it a light watering every day. Doing that will encourage a deeper root system which will help the plants tolerate dry weather better. This is also true for fruit trees. For more information visit UC Pest Note on Watering Fruit and Nut Tress.- July
- Soil Moisture Test
When watering when when is it enough? Whether you are using drip or sprinklers or hand watering, measuring how much water is actually getting down to the plant’s roots is important so you don’t under or overwater. At your local garden center, there is a tool called a moisture meter that can help determine the proper amount to apply. It sells for less than $10 and has a metal probe and a simple needle dial on top that tells you if the soil is dry, moist or wet. The moist reading is recommended. Great for use in pots or on vegetables. One caution, pull the meter out of the soil using the probe rather than the plastic housing on top as the meter can pull apart. A no-cost method is the "finger-test". Using your longest finger, stick into the soil up to your knuckle. Feel if the soil around your finger is dry or moist?- July
- Soil Solarization
Soil solarization can be used to control diseases, nematodes and weeds by baking everything under plastic sheeting.The best time for solarization of soil is from June to August. Leave the soil covered for 4 –6 weeks. Refer to the UC Pest Note on Soil Solarization for Gardens & Landscapes.- June, July, August
- Summertime Care of Roses
Remove suckers (the rapid-growing, long canes) from roses. Prune them below the bud union. Also deadhead roses and apply an organic rose food. Now is a good time to wash off roses using a blast of water from the hose, which should be done occasionally to help remove aphids, ants and mites.- July
- Tomato Bottom Scarring
Sometimes scarring can be seen on the bottom (blossom end) of tomatoes. This can be caused by weather conditions such as cool and cloudy weather at bloom time, making the blossom stick longer to the small fruit. The fruit is perfectly good to eat with the damaged part cut out. Some large heirloom tomatoes are more susceptible to this condition.
Also known as catfacing.
*file245851*- June, July, August
- Water the Roots, Not the Plants
It's tempting to get the hose out and spray your dry, thirsty plants, but you don't want to waste water. Keep their feet nice and cool, but resist the urge to squirt the leaves unless they need a cleaning (for dust or white fly for instance). While it's a common belief that daytime water on the leaves will burn them, it's not very likely based on a study by scientists - the water will evaporate and not do your plants much good during the day, and could encourage fungal pathogens if wet overnight.- June, July, August
- Watering Hydrophobic Soil
Just as a dry sponge repels water, overly dry soil can do the same thing. This dried out soil is called hydrophobic. Hydrophobic soil can waste a lot of water as water drains away from the plant's root zone.
In pots: learn more about how to re-wet very dry soil on our Watering Hydrophobic Soil page. In the yard: setting sprinklers to run for 5 minutes, waiting for the water to soak in, and then running for a longer time can prevent water loss due to hydrophobic soil.- May, June, July, August
- Watering Tomatoes
If you haven't already, it's time to cut back on watering tomatoes. Tomatoes have far more flavor when the ripening fruit is deprived of water. Don't forget to remove competing weeds from around the garden.- July
2. What to plant
- Don't Plant an Invasive Plant
According to PlantRight, so-called invasive plants "escape into open landscapes and cause a variety of ecological problems. They displace native plants and wildlife, increase wildfire and flood danger, clog valuable waterways, degrade recreational opportunities, and destroy productive range and timber lands."
PlantRight has identified the following as invasive in Northern California: Green fountain grass (Pennisetum setaceum), Periwinkle (Vinca major), Pampas grass (Cortaderia selloana), Highway iceplant (Carpobrotus edulis), Mexican feathergrass (Stipa / Nassella tenuissima), Yellow Flag Iris (Iris pseudacrorus), Water Hyacinth (Eichhornia crassipes). For details and recommended alternatives, please consult their Website.- April, May, June, July, August, September
- Tomatillo (Physalis philadelphica)
Tomatillos still to this day is a truly wild plant. Attempts to hybridize them have failed. The plant is native to Mexico and was brought to the U.S. by Mexican Indian immigrants. It has a tart green apple taste and is the main ingredient in green salsas. It is also used in soups, stews, and guacamole.
It is a member of the Solanaceae (nightshade) family as is the tomato and will grow any place a tomato will. It is fairly drought tolerant. Being a wild plant, there is a great deal of variability in plant habit, fruit size, etc. It is an annual, a low growing, sprawling plant usually not more than 2 feet high.
The tomatillo has small, sticky, tomato-like fruits enclosed in papery husks. They are 1 to 3 inches in diameter and green or purplish in color. Culture is very similar to that for tomatoes or peppers. Plantings are generally direct seeded. The first harvest is ready in 70 - 80 days. They are not ripe until the fruit begins to break through the husk.- June, July
- Vegetable Planting Chart
Wondering what vegetables can be planted now? To get the best success—whether planting from seed or transplants—refer to our Santa Clara County Vegetable Planting Chart. It's based on our own garden experiences.- February, March, May, June, July, August, November
3. Pests and Diseases
- Ant Control
On outdoor and sometimes indoor plants, ants protect and care for honeydew-producing insects such as aphids, soft scales, whiteflies, and mealybugs, increasing damage from these pests.
Ants are among the most prevalent pests in households. UC IPM offers steps to follow in an Ant Emergency.
Ant management requires diligent efforts and the combined use of mechanical, cultural, sanitation, and often chemical control methods. It is unrealistic and impractical to attempt to totally eliminate ants from an outdoor area. Focus your management efforts on excluding ants from buildings or valuable plants and eliminating their food and water sources. Reducing outdoor sources of ants near buildings will reduce the likelihood of ants coming indoors.
Ants on Trees and Shrubs
When numerous ants are found on plants, they are probably attracted to the sweet honeydew deposited on the plants by honeydew-producing insects such as aphids or soft scales. Ants may also be attracted up into trees or shrubs by floral nectar or ripening or rotten sweet fruit. These ants can be kept out by banding tree trunks with sticky substances such as Tanglefoot. Trim branches to keep them from touching structures or plants so that ants are forced to try to climb up the trunk to reach the foliage.
When using Tanglefoot on young or sensitive trees, protect them from possible injury by wrapping the trunk with a collar of heavy paper, duct tape, or fabric tree wrap and coating this with the sticky material. Check the coating every one or two weeks and stir it with a stick to prevent the material from getting clogged with debris and dead ants, which will allow ants to cross. Ant stakes with bait can also be used around trees.
For more information about what ant baits and insecticides to use, please consult the UC Pest Note on Ants.- June, July, August
Birds can cause extensive damage to tree fruit crops. Unlike squirrels, birds are more likely to peck at one piece of fruit until it’s gone. If they are doing too much damage, netting over a tree can keep them away from the fruit. If you use visual repellents (such as Mylar streamers or noisemakers) to frighten them, be sure to vary the method so that the birds don’t become immune to the effects. Read the UC Pest Note on Birds on Tree Fruits and Vines for more information.- July, August, September
- Fusarium Wilt
This is the most prevalent and damaging tomato disease. It also starts with the yellowing of lower leaves, but the yellowing may be only on one side (stopping at midrib) of the leaf or just one branch or one side of the plant. The older leaves will droop and curve downward. The yellow leaves wilt and die, gradually killing the whole plant. Sometimes a single shoot is killed before the rest of the plant shows any damage. More information at UC Pest Note on Fusarium Wilt.- June, July
Our local gophers are also called pocket gophers. They make their presence known with crescent shaped mounds of dirt in the garden. Snacking on plant and tree roots as they tunnel through the soil, they are active year round and can have up to three litters each season in well-watered areas. Gophers also gnaw on irrigation lines and divert water into their tunnels, making it difficult to properly water plants. Adults live about three years. Homeowners can use several methods to control them. Locating the main tunnel is the first step. Placing Macabee or Gophinator or box traps or poison baits are explained in detail in the UC Pest Note on Gophers. Another method involves excluding them with wire fencing. Ultrasonic devices and chewing gum have been tested and are not considered to be effective.- May, June, July
- Integrated Pest Management and Beneficial Insects
Our gardens contain far more beneficial insects than pests. Any time pesticides are used, both good and bad insects die. This upsets garden ecosystems. Use of pesticides can also pollute waterways and may put our children and pets at risk, along with other environmental consequences. We can dramatically reduce pest problems by practicing Integrated Pest Management, which includes planting native species, following good cultural practices, and encouraging beneficial insects, such as lady beetles, lacewings and soldier beetles- March, April, May, June, July, August, September, October
- Mosquitoes May Be Breeding In Your Yard
According to Santa Clara County Vector Control, many people are unaware they may be raising mosquitoes in their backyard, they offer tips on identifying possible Mosquito Breeding Grounds. UC has created a video titled Don't Let Mosquitoes Breed in Your Yard.- May, June, July, August, September, October
Have you found snail empty shells stashed in out of the way places, hollowed out Navel oranges, Meyer lemons with no skins, tomatoes with bite marks, fruit with holes gnawed in them or grape skins or cherry tomato skins scattered around? This could indicate the presence of rats. The UC IPM Pest Note on Rats provides a wealth of scientific information.
Rats show up when your citrus, tomato or fruit first start to ripen. Rats are agile climbers and usually live and nest in shrubs, trees, and dense ground cover like ivy. Good sanitation is required. Garbage and garden debris should be eliminated. Use tight fitting lids on garbage cans. Thin out dense vegetation to make the habitat less desirable. Mow ivy once a year to the ground. Climbing ivies on fences or buildings should be removed.
Trapping is the safest and easiest method for controlling rats. The simple snap trap is effective. The most important thing about trapping rats is to have lots of patience and keep trying. Wet some oatmeal enough for it to hold together, add dog or cat kibble or bits of lightly cooked bacon mixed in. Tie a walnut to the trigger and add a dab of peanut butter.
Other baits to try are peanut butter and fresh fruit, but try to have something tied to the trigger. Set traps where rats are likely to travel or where you see droppings along fence lines or buildings. Bait the trap but do not set it for several days. Try different baits in multiple traps until you find one the rats like. Put two traps facing each other. After the rats are accustomed to being fed, then set the traps. If the rat springs the trap but doesn't get caught, move the traps to a different place and change to different baits. Rats prefer secluded spots and will be less wary there. Be sure to secure the trap with a wire or nails. Above all be patient and use multiple traps.- March, April, July, August, September
- Spider Mites
Spider mites are closely related to spiders and are about the size of the period on this sentence. They feed on many kinds of plants. They suck out plant juices from leaves, flowers and the blossom end of fruit. Plant leaves may become stippled with yellow and webs may be visible. Hotter temperatures and dusty conditions encourage them. Conserving natural enemies by not using pesticides, providing sufficient irrigation and reducing dust may all help control mites. Periodic washing of leaves with water can be very effective in reducing their numbers. If treatment is necessary, spider mites can be controlled with insecticidal soap, horticultural oil or neem oil. Releases of predatory mites have been used in some situations. More information is available in the UC Pest Note on Spider Mites.- July, September
- Squash Bugs
Squash bugs are about ½ long, brownish yellow and flattened like a stink bug. Zucchini is one of their favorite plants. Leaves will blacken and drop as they dry. They can be difficult to control. Placing row cover over young plants helps prevent infestation. Remove nearby vegetation where the bugs can over winter. More information can be read at UC Pest Note on Squash Bug.- July
- Squirrel Control
Squirrels can be particularly annoying because they tend to take one bite out of each piece of fruit, rather than eating the whole thing and leaving the other fruit intact. They are difficult to control, but you can try some of the methods recommended in UC Pest Note on Tree Squirrels and UC Pest Note on Ground Squirrels.- June, July, August
- Stink Bugs
Stink bugs are commonly attack tomatoes, squash and beans. Distinctly shield-shaped they may be brown or green. Small bundles of barrel shaped white eggs may be spotted on leaves. Insecticidal soaps are effective against sub-adults. Handpicking adults is recommended. Controlling weeds where the bugs over winter is also a good idea. Find more information at UC Pest Note on Stink Bugs- July
- Sunscald on Fruits and Vegetables
Fruits and vegetables can get sunburned in the summer heat. This is more commonly called sunscald and it frequently affects peppers, tomatoes, and persimmons. The leaves shield the produce from the sun, so it helps to make sure the plants have sufficient fertilizer and water for a healthy plant. You can cut out the damaged parts and eat the rest of the fruit.- July, August
- Tomato blossom end rot
A brown depression on the bottom of tomatoes is usually blossom end rot. This disorder is related to a calcium deficiency aggravated by irregular watering. Since most soils have adequate calcium, watering is usually the problem. Without regular watering, the calcium in the soil cannot reach the plant. Mulching can help. Water tomatoes regularly. Avoid flooding them so the roots sit in water.- July, August, September
- Tomato Hornworm
If you have a hornworm, you will know it. You will look at your plant and a good portion of it will be missing, eaten by the hornworm. All that is left are some large black droppings, the remains of your leaves. You may see this first, because they are the same color as the leaf and are hard to see. They are the largest caterpillars you will see in the garden, as long as four inches, with a distinctive horn or thorn on the rear end. They are beautiful, with white striping and little round circles. The amount of damage they do is unbelievable. Hand pick to control or use Bacillus thuringiensis (BT). More information in the UC Pest Note On Tomato Hornworms.- July
- Tomato Russet Mite
Tomato russet mites deplete juice from the cells of leaves, stems and fruit. They usually start at the base of the plant and move upward. If not controlled, these pests can kill plants. At first sign of damage, treat with sulfur dust or a spray solution of wettable sulfur and spreader-sticker. More information ia found in UC Pest Note on Tomato Russet Mite.- June, July, August
- Verticillium Wilt
Verticillium wilt is a soil-borne fungal disease that damages plant veins. The damage is characterized by affecting one side of the plant. The leaves may wilt and turn brown, dying upward from the base of the branch to the tip. Dead leaves often fall, but may not. Mildly affected plants may survive if fertilized and encouraged into vigorous growth. The fungus can live for years in the soil.
Planting tomatoes, peppers, eggplants, and potatoes (all members of the Solanaceae or nightshade family) in the same place no more than once every three years helps reduce the fungal population to non-harmful levels. Soil solarization may eliminate Verticillium wilt from infected soils. Crop rotation with cereals or broccolis can reduce the pathogen. Avoid high nitrogen fertilizers. Plant Verticillium wilt-resistant varieties of tomatoes, potatoes or strawberries. Refer to the UC Pest Note information on Tomato, Potato, and Strawberry for species-specific suggestions.- May, June, July, August
- Weed Management
Whichever variation of “One year’s seeds makes seven years’ weeds” you prefer, the truth remains: a key part of weed control is not letting them go to seed. For best results, work on removing weeds before they go to seed, and when the ground is moist. Hand pulling and hoeing are effective methods for killing many common weeds. Knowing what kind of weeds you have can be helpful in choosing the best management method - to learn more, see UC's Weed Gallery for help identifying weeds and the UC Pest Note on Weed Management in Landscapes for information about control.- February, March, April, May, June, July
Whiteflies are tiny, sap-sucking insects that may become abundant in vegetable and ornamental plantings, especially during warm weather. They excrete sticky honeydew and cause yellowing or death of leaves. Outbreaks often occur when the natural biological control is disrupted. Management is difficult once populations are high.- June, July, August, September
Whiteflies use their piercing, needlelike mouthparts to suck sap from phloem, the food-conducting tissues in plant stems and leaves. Large populations can cause leaves to turn yellow, appear dry, or fall off plants. Like aphids, whiteflies excrete a sugary liquid called honeydew, so leaves may be sticky or covered with black sooty mold that grows on honeydew (See UC Pest Note on Sooty Mold). The honeydew attracts ants, which interfere with the activities of natural enemies that may control whiteflies and other pests.
Management of heavy whitefly infestations is difficult. The best strategy is to prevent problems from developing in your garden or landscape. In many situations, natural enemies will provide adequate control of whiteflies; outbreaks often occur when natural enemies are disrupted by insecticide applications, dusty conditions, or interference by ants. Avoid or remove plants that repeatedly host high populations of whiteflies.
In gardens, whitefly populations in the early stages of population development can be held down by a vigilant program of removing infested leaves or hosing down with water sprays. Reflective mulches can repel whiteflies from vegetable gardens, and yellow sticky traps can be used to monitor or, at high levels, reduce whitefly numbers. If you choose to use insecticides, insecticidal soaps or oils such as neem oil may reduce but not eliminate populations. Systemic insecticides may be more effective but can have negative impacts on beneficial insects and pollinators.
For more information see UC Pest Note on Whiteflies.