Here are some suggested lawn, landscape and garden activities for May from Purdue Extension publication HO-91-W, “Spring Garden Calendar,” by Purdue Extension specialists B. Rosie Lerner and Michael N. Dana.
Note that timing horticultural events and practices can vary from year to year, depending on weather conditions. The following information is intended as a general guide. Adjust activities according to local weather and site conditions, and be sure to read and follow label directions thoroughly on all products.
Indoor plants and activities
• Many indoor plants can be moved to a shady location outdoors after danger of frost is past (mid-May in northern Indiana). Plants will dry out more when kept outdoors, so check soil moisture often. Sinking the pots in the ground will help slow down moisture loss, but regular watering will still be necessary.
• Use cuttings of houseplants to increase your collection or share with your friends. Root the cuttings in media such as vermiculite, perlite, or potting soil rather than water. Roots grown in water tend to be weak from lack of oxygen and do not adjust well to being planted in soil.
Woody landscape plants and fruit trees
• Thin fruits of apple (and other fruit trees if needed) about three weeks after petal fall. Apples should be spaced on the average about 8 inches apart; peaches at 6 inches apart. If a large crop is set and no thinning is practiced, all fruit will be small and branches may break.
• Apply fungicide sprays to roses to control diseases such as black spot.
• Prune early spring flowering trees and shrubs after flowers fade.
• If needed, apply billbug control to prevent egg laying or damage from larvae feeding.
• Apply post-emergence herbicides to control broadleaves if they are a problem. Be careful to avoid spraying or drifting herbicide onto garden plants.
• Fertilize in May using a 4-1-2 ratio of nitrogen, phosphorus, and potassium at the rate of 1 pound of actual nitrogen per 1,000 square feet.
• If needed, apply insecticides to control sod webworm.
• Begin now to search for sod webworm or other turf-feeding caterpillars. Apply chemical controls only if a large number of caterpillars are present.
Flowers, vegetables and small fruit
• Allow foliage of spring-flowering bulbs to remain in place after blooms fade. Leaves manufacture the food reserves, which are then stored in the bulb for a repeat showing next year.
• Plant frost-tender plants after danger of frost is past for your area.
• Pinch chrysanthemums and annual flower plants to keep them compact and well-branched.
• Make successive plantings of beans and sweet corn to extend the season of harvest.
• Thin seedlings of earlier-planted crops such as carrots, lettuce, spinach, and beets to their proper spacing.
• Harvest early plantings of radishes, spinach, and lettuce.
• Harvest asparagus by cutting or snapping spears at, or just below, the soil level.
• Harvest rhubarb by cutting or by grasping the stalk and pulling up and slightly to one side.
• To prevent bacterial wilt in cucumbers, control cucumber beetles, the carriers of the disease, as soon as plants germinate or are transplanted.
• Remove blossoms from newly set strawberry plants to allow better runner formation.
• Remove unwanted sucker growth in raspberries when new shoots are about a foot tall.
JOHN WOODMANSEE is the agriculture and natural resources educator for Noble County with the Purdue University Cooperative Extension Service in Albion.