June

General Garden Care

Mulch all garden beds after thoroughly weeding and watering. Use 1 to 2 inches of shredded bark on new perennial and flower beds and larger chips around tree root zones. Mulch conserves moisture, protects the root zones of plants and helps keep weeds down.

Although the drought is no longer a threat (at least for now), make sure all newly planted trees, shrubs, perennials, roses, etc. are watered deeply once a week, in the event rainfall does not occur.

Woody Plant Care

Fertilize roses with a second application of a liquid 20-20-20 fertilizer after the first flush of flowers. Continue to monitor for black spot. Remove infected leaves immediately and begin a spray program with an approved fungicide. Most products must be reapplied following any rainfall.

Deadhead hybrid tea roses as soon as flowers fade. Many shrub roses are self-cleaning and don’t require deadheading. When in doubt, lightly prune old blossoms to keep plant looking attractive.

Pinch off 1 inch of sticky new green growth on azaleas and rhododendrons to increase next year’s flowers. Mulch acid-loving plants with shredded pine needles and/or shredded oak leaves.

Continue to prune all spring-flowering shrubs immediately after they flower.

Small evergreens, such as boxwood or yew, can be lightly pruned after the new growth fills in to maintain formal character.

Annual and Perennial Care

When cutting peony blossoms to bring indoors, remove as few leaves as possible from the plant. Don’t cut more than 25 percent of the flowers from one bush and avoid cutting flowers from newly planted peonies.

Deadhead annuals and perennials to encourage new flower formation.

Stake tall perennials and continue to tie annual and perennial vines to supports. Train and tie clematis stems with soft cloth to guard against breakage caused by stems blowing in the wind.

Continue to spray emerging summer-blooming lilies with anti-rodent products, if rabbits and deer have been a problem. Next year, plant fritillaries and allium bulbs next to lilies to discourage browsing.

Fertilize annuals in containers, baskets and window boxes with a quarter-strength balanced fertilizer every seven to 10 days. Always water the plants before adding liquid fertilizer.

Fertilize bulbs with a 9-9-6 slow-release fertilizer if you did not do so at planting time. Mark the spots with small stakes to repeat fertilizer application in the fall (when plants are not visible).

Continue to remove yellowing leaves of summer-flowering bulbs.

Amaryllis plants should be placed in morning sun and fertilized twice a month with a 15-30-15 liquid. Leaves will continue to grow all summer as they manufacture food for the bulb. Don’t forget to water the bulbs.

Continue to pinch off new growth of chrysanthemums, asters and late-blooming tall sedums.

Sow seeds of perennials directly into the garden this month for next year’s bloom. Mark the spots carefully.

Monitor succulent new growth for signs of aphids (puckered stunted leaves). Hose down affected plants. Don’t use strong chemicals if ladybugs are present since they are predators of aphids.

Hot, dry weather can result in increased mite activity. Symptoms include stippling of foliage. Remove affected foliage. Strong miticides will also kill beneficial mites.

Lawn Care

Monitor lawn for weeds. Rain and warm water will push grass to grow fast. Mow high (2 to 2-1/2 inches) in hot, dry weather so individual blades of grass can shade each other. Try to leave grass clippings on lawn, but avoid clumping. Rake clippings evenly across dense grass areas to break up clumps or to dry before adding clippings to compost pile.

Seed bare areas of lawn with appropriate grass seed mix and starter fertilizer. Keep area moist until seeds germinate. Do not mow for several weeks as new grass thickens up.

Do not fertilize lawn in hot weather. Best time to fertilize is fall.

Water lawns, if necessary. Grass can go dormant for several weeks in intense heat and requires only 1/2 inch of water to keep crowns alive. Avoid watering midday or on windy days. Soaker hoses are a direct and efficient method of watering.

If grubs have been a problem in past, treat affected areas with a product containing imidacloprid. The best time to apply in Chicago area is mid- to late June. Water in well. Grubs damage lawns by chewing the grass roots so the above-ground turf turns brown and pulls up from the ground like a carpet. Grub damage usually shows up in later summer, but at that time it is often too late to treat effectively. Treat later in June for damage observed last summer. Spot-treat problem areas rather than broadcasting product over entire lawn. Call Plant Information for current methods and dates of grub control at (847) 835-0972.

Fruit and Vegetable Gardening

Stake or cage tomatoes as they begin to grow.

Harvest peas, raspberries and all cool-season lettuces and vegetables as they ripen.

If squash vine borer has been a problem in your garden, cover small transplants of squash, cucumbers and zucchini with row covers to prevent moths from laying eggs on vines. Remove row covers when plants begin to flower. Consider planting disease-resistant varieties next year.

Pinch new top growth of herbs to keep them from flowering. This intensifies the oils and flavor in the foliage. Snip or cut off sprigs of herbs to use in cooking all season. Portions of fresh herbs can be cut, frozen or dried during summer to encourage plant to produce more growth.

A fascinating nature project for families is to plant dill or fennel to attract swallowtail butterflies to lay their eggs. Watch for tiny eggs to develop into plump caterpillars that will feed on the herb foliage before pupating into butterflies.

Plant pumpkins at the first of the month. Large varieties require a 100-day growing season. If you gently carve names in developing pumpkins, the letters will enlarge as pumpkins grow.

In late June sow seeds of corn, bush beans and cabbage for an early fall harvest.

Mulch vegetable garden with straw to retain moisture.