Encourage new growth

Help plants mature as the growing season unfolds:

• To promote a second, late-summer flower show, cut back, shear, or remove flower spikes from the following early-blooming perennials: perennial salvia (Salvia spp.), spike gayfeather (Liatris spicata), and tickseed (Coreopsis spp.).
• Remove spent flowers or seed heads of daylilies (Hemerocallis spp.) immediately to conserve plant energy.
• Some perennials that tend to flop or grow too tall, such as Aster (Aster spp.), Phlox (Phlox spp.), and salvia (Salvia spp.), can be cut in half in late May or early June to regulate their height, but this practice should stop by early July to allow the plant to set buds and flower.
• Continue to deadhead roses by cutting blossoms back to the first set of five leaflets that points away from the center of the plant.

Provide support for tall plants and vines

Stake tall plants, if necessary. Continue to guide clematis vines and all other soft-stemmed vines to their supports using soft, nylon ties. Learn more about vines here.

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Sow perennial seeds

Seeds of perennials can be sown directly into the garden this month. Note their location to avoid accidental “weeding” next spring; golf tees can provide an unobtrusive reminder.

Caring for Oriental poppies

By midsummer, the foliage of plants such as Oriental poppies (Papaver orientale) fades and dries. Consider planting annuals or later-blooming perennials in front of them to conceal their unattractive yellowing foliage. If necessary, dig and divide Oriental poppies, keeping in mind that they don’t like to be moved. Plant them in a sunny, well-drained area.

Continue monitoring for infestations

The lush greenery that grew abundantly during a rainy spring could become a target for insects. Monitor plants closely but avoid drastic action or strong chemicals until insects are correctly identified. When in doubt about insects or disease and what, if any, actions to take, contact the Garden’s Plant Information Service.

Some tips:

• Many infested plants can be hosed down to remove small insect populations, such as aphids. Aphids have many natural enemies and are rarely cause for harsh pesticides.
• Monitor foliage of densely planted annuals and perennials that might indicate fungal attacks due to cool, damp weather earlier in the season.
• Inspect roses closely for blackspot. Remove any leaves that show darkened circles with fuzzy margins on either the 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 and carefully follow label directions. Consider planting disease-resistant roses in the future.

Keep harvesting herbs

Herbs like to be snipped. Continue to harvest leaves to use fresh, or preserve for later use by drying them or freezing them in small batches in an ice cube tray. Also, pinch off any developing flowers, which helps plants retain essential oils and flavor in their foliage.

Harvest onions and garlic

as they are ready, and begin the drying process.

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 as well as containers.

Cool, wet spring? Determine fertilizer needs

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

Mow high

In July’s peak summer heat, mow grass at a high level, 2½ to 3 inches. If using a mulching mower, leave grass clippings to help feed the lawn. Avoid leaving large clumps of grass on the lawn; gently rake them to distribute evenly or add them to your compost pile.

Dealing with drought

It’s OK to let lawns go dormant during drought or times of water conservation. Although the turf will go dormant, the grass plants’ crowns will remain alive with about 1 inch of water applied every four weeks.

Bypass fertilizer

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

Avoid herbicides

In July’s hot weather, herbicides will not be as effective and may burn the lawn. Pull out annual weeds, such as crabgrass, before they go to seed.

Outdoor Container Care

Water as needed

Annuals in containers and hanging baskets may require daily watering during hot and/or windy weather, which dries soil more quickly.

Fertilize plants

Continue to fertilize container plants with half-strength of a balanced liquid fertilizer, but avoid applying in the heat of the day or during long, hot dry spells. Always water plants before fertilizing.

Summer pruning with a light touch

Light pruning tasks this month can help keep trees and shrubs attractive and healthy.

• If not done yet, renovate overgrown shrubs including forsythia (Forsythia spp.), lilac (Syringa spp.), and redtwig dogwood (Cornus alba) by removing one-third of the oldest canes.
• Don’t delay pruning shrubs that bloom on old growth. Pruning these later in the fall may impede next year’s blooms.
• Prune out ground-level sucker growth by cutting out growth below soil level from apple and crabapple (Malus spp.), apricot (Prunus armeniaca), peach (P. persica), and plum trees (P. domestica).
• Prune out weak, green but fast-growing water sprouts that grow vertically from branches of fruit trees, redbuds (Cercis spp.), or other ornamental flowering trees.
• If necessary, boxwood (Buxus spp.) shrubs can be lightly pruned to maintain geometric form. Avoid over pruning, especially in very sunny, hot weather.

Monitor apple trees

Inspect apple trees beginning in July, when apple maggots are laying their eggs. Some gardeners place apple-maggot fly traps that resemble red apples in trees to trap these pests. When the insect count reaches a high level, control steps are then taken. Contact the Plant Information Service for current control methods.

Inspect for Japanese beetle damage

These iridescent insects skeletonize foliage but will finish feeding by the second week in August. Favorite host plants include roses and grapevines, and birch (Betula), crabapple (Malus), elm (Ulmus), linden (Tilia), and maple (Acer) trees. They are often found feeding on the tops of plants. If possible, hand remove them by knocking them into a large jar of soapy water: Hold the jar directly below the feeding beetles. When disturbed, they usually drop straight downward—right into the jar.

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