May Gardening Tips
- Set out traps for earwigs, slugs, and whitefly.
- Thin pit fruits at or before pit hardening.
- Thin apples when ½” diameter.
- Mow grass or cultivate soil around orchard to discourage thrips and plant bugs.
- Mulch around plants to control weeds and conserve moisture. Be sure to leave a small circle of bare soil around the base of each plant.
- Deep water trees and shrubs. Build water basins, but do not allow water to stand against the trunks.
- Prepare dahlia bed with rich soil.
- For continued bloom, cut off spent flowers.
- Hang strips of foil or CD’s in fruit trees to help deter birds.
- As spring=flowering shrubs finish blooming, prune to shape, removing old and dead wood.
- Trim hedges; lightly trim azaleas, fuchsias, bushier plants.
- Thoroughly clean debris from ponds, fountains and bird baths.
- Check dates of Master Gardener classes.
- Strawberries (end of May).
- Kiwi, ? recommended NPK.
- Young fruit trees, if missed in April.
- Cane berries after harvest.
- Rhododendron after bloom.
- Cool season turf grass.
- Roses at bloom start.
- Corn – N when knee high.
- If you did not use slow release fertilizer for summer bloomers. Give then a feeding now.
- Fertilize vegetables monthly.
- Feed indoor plants with slow release fertilizer.
Spray: Check the California Backyard Orchard website for current information.
- Apples and pears for codling moth: first treatment when pears are ½” in diameter and apples are ?”. For timing use codling moth traps or call Master Gardeners at (530) 621-5512.
- For codling moth control, attach 4” corrugated cardboard bands around tree trunks in early May; in late May or early June remove and destroy bands to kill the larvae and pupae found in the cardboard.
- Check for citrus scale and control with horticultural oil. Encourage natural enemies and protect trees from ants.
- Roses with Funginex. Best time is morning or evening and after plants have been watered.
- Continue application of sulfur or other fungicide to grapes if damp weather persists.
- If needed, apply Tanglefoot around tree trunks to deter ants and other crawling insects.
- Pears, except Comice – weak copper spray when in bloom, one to three applications for fireblight.
- Check roses for black spot, mildew and rust and spray if needed
- Check roses for aphids; control with a strong spray of water or insecticidal soap.
Note: all the effective insecticidal sprays kill bees and other beneficial. Do not spray while trees are in bloom.
What To Plant In May
- Beans, beets, carrots, corn, cucumber, melons, okra, parsley, parsnip, peppers, pumpkins, radish, all squash, tomatoes.
- Cannas, lilies, tuberous begonias.
Plant Seed - Greenhouse or Cold Frame
- Time for house cleaning.
Set out Plants
- Eggplant, herbs, parsley, peppers, tomatoes, all vine crops.
- Marigolds, zinnias, snapdragons, sunflowers, hollyhock, dahlias, lobelia, salvia, cosmos.
- Transplant tomatoes, eggplant and peppers as temperatures warm.
- At cooler elevations, transplant lettuce cabbage family, collards and kale.
- Plant cilantro and two week intervals for a steady supply.