Garden Tips for April

Several fungi types cause powdery mildew, and it affects many plants including grapes and roses. (Viktor / Adobe Stock )
Peyton Ellas is a UCCE Master Gardener and is owner of Quercus Landscape Services and Auntie's Home Grown Farm in Springville.

Are you enjoying spring so far? We are enjoying another “superbloom” year for native wildflowers. If you can, take a drive to see some of the wildflowers. In our gardens, too, we should see foliage growth and flowers. This is a month of plenty of activity and plenty of chances to be outside enjoying and working in our gardens. 

Planting: Transplant seedlings of tomatoes, peppers, eggplant, okra, and sweet potatoes this month. Plant seeds or transplant seedlings of summer and winter squash, cucumber, and melon. Towards the end of the month, plant seeds of beans and corn. Early in the month, you can still plant radishes, greens, and onions, but be prepared to harvest them while small; they will go to flower quickly in the lengthening days and warm temperatures. 

You can plant almost any ornamental tree, shrub, perennial, and ground cover this month, including citrus and avocado. Annuals for summer flowers to plant include zinnia, sunflower, marigold, and petunia. Don’t be too quick to remove stock and snapdragon; many of the newer varieties withstand the heat better than their ancestors. 

Maintaining: Prune flowering shrubs when they finish blooming: azaleas, camellias, forsythia, lilacs, ceanothus, and native California sage like Pozo Blue. You can continue to prune deciduous trees if you haven’t yet; it may slow the growth a little but won’t hurt them. Ruthlessly thin stone fruits while the fruit is still tiny, to about six-to-eight inches apart. Mow lawns to three inches tall. Mowing lawns too short encourages weeds and diseases.

Monitor for common spring pests like aphids, earwigs, slugs, snails, whitefly, thrips, and codling moth worm. Handpicking or spraying with a strong stream of water is the least toxic option. If you must use pesticides, take the time to identify your pest insect first to avoid harming beneficial insects like lacewing, syrphid fly, spiders, parasitic mites, parasitic wasps and lady bug larva. Remember that caterpillars are our future moths and butterflies, which provide food for birds and other creatures. Caterpillars on ornamentals can often be ignored unless in large populations; one easy method is to remove them from the plant (with gloves on because some caterpillars can sting and some spiny ones can cause rashes) and avoid inorganic pesticides.

Fertilize acid-loving plants (azalea, camelia, gardenia, blueberry) with specialized fertilizer. There are also specialized fertilizers for lawns, citrus, and roses. These special fertilizers contain the trace minerals needed in addition to the big three (nitrogen, phosphorus, potassium). April is also a good month to fertilize stone fruit and nut trees and container plants. Avoid over-fertilizing. When in doubt, use a half-strength mix. Don’t assume all weak or struggling plants require fertilizer. It’s best to determine the cause of the symptoms to avoid harming by stressing your unwell plant. Adding fertilizer is a stressor.

Powdery mildew is a common disease problem in spring. Initial symptoms appear on leaves as yellowish spots on the upper leaf surface followed a short time later by fuzzy white powdery stuff on the bottoms of the leaves. Several fungi types cause powdery mildew, and it affects many plants including grapes and roses. Manage it by growing resistant plant varieties and altering the growing environment, such as increasing the air circulation by pruning and providing more sunlight to affected plants, even in some cases by transplanting them. Fungicide treatments might be required for susceptible plant species, but the cultural practices are more effective. Learn more.

And the weeds continue. Remove as many as you can, or at least remove the seed heads if you can. Avoid bare dirt, which makes erosion issues worse. It’s okay to chop weeds down but leave the roots, especially for annual weeds.

Monitor and set baits for ants, which especially like spurge and spotted spurge. Remember to change the ingredients (which are different from the brand name) of your ant baits every few months.

Conserving: A healthy garden is an active one. Consider sharing the garden with insects. Determine a management threshold for common pests so you don’t feel pressured to eliminate all insects, all weeds. You can have a healthy, vibrant, food and flower-producing garden even with a few pests. Healthy insects mean healthy food for birds. Train yourself to practice Integrated Pest Management (IPM). The first guideline is Least Toxic First. Conservation doesn’t mean you give in/give up, never spray again. It means being educated on what method to use and when.

Don’t get discouraged if you’re a new gardener. Gardening is a partnership between humans, insects, birds, weather, plants, mammals, and soil micro-organisms. Did you think you were gardening alone? Master Gardeners are also here to help, as is the entire UC IPM program online backed up by hundreds of researchers.

As always, conservation means irrigating the landscape and edible garden efficiently even in a non-drought year. Look for leaks and repair them. Adjust irrigation controllers. Avoid runoff and over watering. Consider adding a rain garden or simple swale to keep storm water on your property. Even urban gardens can have a small retention basin.

Enjoy the month of sunshine, vigorous garden life and, yes, even a few storms.

Gardeners will be live to answer your questions on Saturday, April 6, 8 to 11 a.m. at the Visalia Farmers’ Market at its new location, Tulare County Courthouse north parking lot in Visalia. You can also contact them at 559-684-3325, or visit their web site at ucanr.edu/sites/UC_Master_Gardeners.

This column is not a news article but the opinion of the writer and does not reflect the views of The Sun-Gazette newspaper.

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