April Tips & Events for Santa Clara County
"Spring translates earth's happiness into colorful flowers" ~Terri Guillemets
Monthly Tips
Young Fruit Trees
Painted tree trunks Photo by Jack Kelly Clark-UC
If you have young fruit trees, particularly ones you just planted during bare root season, you want to protect them while they’re still delicate. Water them regularly while they are establishing their root system. Put mulch around the root area to hold in moisture, moderate the soil temperature, and help keep weeds from sprouting and competing for water and nutrients. Consider painting the trunk with white latex paint, diluted 50% with water. This will reflect the sun and help prevent sunburn. Sunburn is a problem because the bark can crack, allowing pests and diseases to enter the wood more easily. Once the tree is larger and has a full canopy, the leaves will normally provide sufficient protection.

Photo: Painted tree trunks, by Jack Kelly Clark, UC
Late Oranges
Orange left on tree past its prime Photo by Laura Monczynski
This year it’s been harder to share oranges because of plant quarantines and people quarantines, so you may still have a lot of oranges on the trees. Even the ones that don’t fall will not stay good forever. The skin may start to ripple as the fruit inside starts to dry and suffer in quality. Rather than leave it to rot or be eaten by rats, pick what is left soon. You can store them in the refrigerator for several weeks, but keep an eye out for mold. You can freeze orange sections for later use in orange juice or smoothies, or you can make marmalade or other orange recipes if you have already eaten enough fresh oranges. Picking the remainder allows the tree to put more energy into the current blossoms which will become next year’s fruit. (Valencia oranges, less common in our area, can be harvested through summer.) 

Photo: Orange left on tree past its prime, by Laura Monczynski
After the Spring Bulbs
Depending on the sun and warmth of the location where you planted spring-blooming bulbs, they may already be finished or they may just be starting to bloom. If they are still actively growing and blooming, adding a little fertilizer will give them food for next year. If there is inadequate rainfall, continue to water them until about a month after they finish flowering. Cut the stalks from the finished blooms all the way back to the base, but leave the leaves. They will continue gathering energy for the future. Once the leaves are completely dry and straw-like, they too can be removed. If the plants seemed crowded and the flowers were getting smaller, carefully dig them up, separate the bulbs, and replant them spread out. Toss any bulbs (bulbs/corms/rhizomes/tubers) that are mushy or show other signs of rot. And continue to enjoy easy-maintenance flowers year after year.  

Photo: Triteleia laxa, a California native bulb, by Allen Buchinski
Summer Vegetables
Seedlings under fluorescent lights Photo by Laura Monczynski
Many summer vegetables can be started now from seed indoors or in a greenhouse. The ground is still too cold for summer seeds to germinate or for the plants to go into the ground. Depending on the weather we get this spring, it will likely be May or June before the soil is warm enough. Soil in containers or raised beds will warm up earlier in the season. Starting plants in pots will give them time to get stronger before putting them near potential pests. It will also allow you to continue enjoying current cool season vegetables. Be sure to provide light once the seeds germinate, if the seedlings are not in natural sunlight. Seedlings with insufficient light will grow tall and thin and leggy and will not be as strong. If they are growing too large for the pots they are in, transplant them into larger pots. The same can be done for seedlings purchased from a nursery. Some popular summer vegetables are tomatoes, peppers, cucumbers, squash, and melons.

Photo: Seedlings under fluorescent lights, by Laura Monczynski
Fire Blight
This disease is so named because brown or black leaves, fruit, and branches look as if they have been burned. It is most common on apple and pear trees. The bacteria enter through the blossoms and travel down the tree. If left unchecked, fire blight can enter the trunk and kill the entire tree. Prune infected branches back to healthy wood, at least eight inches below visible damage. If the inside of the branch is discolored, you need to cut back still further. Clean pruning tools between cuts so as not to spread the infection. A less effective way to control fire blight is to spray the open blossoms with a copper spray. Planting varieties that are less prone to fire blight is helpful. Always promptly clean up fallen fruit and leaves.

Photo: Fire blight on a pear tree, by Allen Buchinski
Upcoming Events
Cool season greens by Jennifer Baumbach UCCE Master Gardener Coordinator Solano County
We regret that we will not be holding a 2021 Spring Garden Market due to COVID restrictions. We hope to return with a full event in 2022.


Vertebrate Pest Management for your Yard and Garden, Thursday, April 8, 5–6:30 pm, Online

Plant Clinic, Saturday, April 10, 10 am–noon, Online


Navigating the UC IPM website, Thursday, April 15, 1–2:30 pm, Online

Growing Fabulous Citrus, Wednesday, April 21, 4–5:30 pm, Online

Replacing Your Lawn, Wednesday, April 28, 4–5:30 pm, Online

Household pests, Thursday, May 20, 1–2:30 pm, Online
Check our calendar for the latest schedule of events. Videos of many past presentations are also available.

Photo: Cool season greens
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University of California Master Gardener volunteers promote sustainable gardening practices and provide research-based horticultural information to home gardeners. Visit our website for more information including:

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