July

General Garden Care

Newly planted trees, shrubs, perennials, roses must receive 1 inch of water per week throughout their root zones. This is especially important in hot, dry weather.

Continue to cultivate and weed. The return of hot weather will certainly push weed growth.

If not done yet, mulch garden beds immediately after weeding with 2 to 4 inches of shredded bark. This is the best way to retain moisture and keep weeds under control.

Woody Plant Care

Fertilize roses for the third and final time at the end of the month with a liquid 20-20-20 fertilizer. Do not fertilize after August 1.

Continue to deadhead roses by cutting flowers back to the first set of five leaflets.

Monitor roses closely for blackspot. Conditions earlier this season were perfect for encouraging this fungal condition. Remove any leaves that show darkened circles with fuzzy margins on either topside or underside of leaves; yellow foliage with dark spots; and any leaves that have already dropped from the plant. Begin a spray program with approved fungicides immediately. Always choose disease-resistant roses in the future.

If not done yet, renovate overgrown shrubs including redtwig dogwood, lilac and forsythia by removing one-third of the oldest canes.

Prune out all ground-level sucker growth from crab apple, apple, plum, peach or apricot trees by cutting out growth below soil level.

Prune out weak, green but very fast-growing water sprouts that grow vertically from branches of fruit trees, redbuds or other ornamental flowering trees.

If necessary, boxwood and yews can be lightly pruned to maintain geometric form. Avoid overpruning, especially in very sunny, hot weather.

Annual and Perennial Care

Continue to deadhead annuals and perennials to encourage more flowering. When deadheading annual geraniums, remove entire stem with fading flowers.

Prune out longest stem of cascading petunias weekly to prevent plants from becoming scraggly.

To promote a second, late-summer flower show, cut back, shear or remove flower spikes from the following early blooming perennials: catmint, geraniums, salvia and delphiniums.

Annuals in containers and hanging baskets may require daily watering during hot or windy weather. Continue to fertilize container plants with half-strength balanced liquid, but avoid applying in the heat of the day or during long, hot dry spells. Always water plants before fertilizing.

Remove spent flowers or seedheads of daylilies immediately to conserve plant energy.

Monitor foliage of densely planted annuals and perennials that might show fungal attacks due to cool, damp weather earlier this season.

Continue to pinch out new growth of tall sedums, asters and chrysanthemums until the middle of the month.

Stake tall plants, if necessary, by tying with soft nylon ties.

Continue to guide clematis vines and all other soft-stemmed vines to their supports.

Make note of empty spots in borders that might benefit from planting summer-flowering bulbs next year.

Seeds of perennials can be sown directly into the garden at this time. Note location to avoid accidental "weeding" next spring.

If necessary, dig and divide Oriental poppies as their foliage yellows and dries. Always plant poppies in sunny, well-drained areas. Avoid moving poppies, if possible. Since poppies fade out by midsummer, plant annuals or later-blooming perennials in front of them to conceal their unattractive yellowing foliage.

The lush greenery that grew abundantly during a rainy spring might become a target for insects. Monitor closely but avoid drastic action or strong chemicals until insects are correctly identified. Many, like aphids, will go away with a strong stream of water from a hose. Aphids have many natural enemies and are rarely cause for harsh pesticides. When in doubt, visit Plant Information at the ChicagoBotanic Garden.

Lawn Care

Do not fertilize lawns in summer. Early fall is the best time to apply a 3-1-2 ratio fertilizer.

During drought or times of water conservation, turf will go dormant, but the grass plants’ crowns will remain alive with only 1 inch of water.

Mow grass at a high level in hot summer, 2-1/2 to 3 inches. Grass clippings can be left on the lawn and gently raked to avoid clumping.

Avoid using herbicides in hot weather. Always read directions carefully. Pull out annual weeds, such as crabgrass, before they go to seed.

Fruit and Vegetable Gardening

Continue to harvest herbs to use fresh, dry or freeze in small batches in ice cube tray. Pinch off developing flowers to retain essential oils and flavor in the plants’ foliage.

Monitor tomatoes during hot weather. Tomatoes appreciate an even supply of moisture rather than a heavy soaking and then a drought. Straw mulch is helpful in these beds.

Many hot weather-loving veggies, such as peppers, tomatoes, eggplants and cucumbers, might be delayed in fruit production due to a cool, wet spring. Side dress these vegetables with a nitrogen fertilizer, taking care not to spread it on the plants’ foliage. Water in well.

Monitor vegetables for symptoms of fungus or blight: soft, darkened areas, yellow and dropping leaves, sunken dark spots on otherwise green foliage.

Harvest onions and garlic as they are ready and begin the drying process.

Seeds for fall crops may be sown toward the end of the month. These include beans, broccoli, spinach, cool-season lettuce crops and cabbages.

Monitor all plants for insects. The return of sunny, hot weather will bring a bumper crop of insects. Hand-remove large insects such as tomato hornworms and other caterpillars.

Caterpillars on fennel, dill and carrots might likely be those of swallowtail butterflies, which lay their eggs on these favorite host plants. Consider planting a special herb crop just for them next year.

Monitor apples during late July when apple maggots are laying their eggs. Visit Plant Information for current control methods. Some gardeners place red decoy apples in trees to trap these pests. When the insect count reaches a high level, control steps are then taken.

Espaliered fruit trees should be pruned for the second time once their spring flush of growth is over. The first pruning is done in late winter when plants are dormant.