July Gardening Tips and Tasks

• Reconsider spraying pesticides. There is a lot of insect activity this time of year, but not all insects are pests and/or warrant chemical controls. Identify an insect before considering it a pest and look into more sustainable pest control options. For sustainable management options and identification help, search our different outdoor insect management pages or send questions and photos through Ask Extension.
• Too much or too little rain? Climate change brings more variable and more severe weather - heavier rainfall events, or periods of drought. Incorporate stormwater practices like rain gardens and conservation landscaping to minimize flooding and erosion problems. In droughts, use drip irrigation to minimize water waste.
• It's time to think about fall planting! You can grow a variety of vegetables to harvest this fall, and some food crops can survive through the winter under protective row covers.

• Mulch your landscape now if you haven’t done so already. Mulch helps keep weeds down and conserves soil moisture. Mulch should be applied 1 to 3 inches deep and kept away from tree and shrub trunks.
• If you planted new trees and shrubs this spring, remember to check your soil moisture at least once each week and keep up with watering, as needed.
• Planting trees to shade your home in the summer can help reduce the costs of air conditioning. Plan now for tree selection and placement. The next best time to plant trees will be in early- to mid-autumn.

• Native plants that bloom in the summer support native bees, butterflies, and hummingbirds. Examples of summer-blooming perennials include wild bergamot (Monarda fistulosa), narrow-leaved mountain mint (Pycnanthemum tenuifolium), black-eyed Susan (Rudbeckia species), and blazing-star (Liatris spicata).
• Chrysanthemums and asters should be cut back halfway by mid-July to encourage fall blooming. If not trimmed, they will bloom later this month and not in the fall.

• Sow seed for fall transplants of broccoli, kale, turnip, and cauliflower in flats or containers by the third to fourth week in July. Late crops of squash, beans, and cucumbers can be direct-sown into your garden through the end of July in central Maryland (adjust dates for other regions).
• Blossom-end rot of tomato, pepper, squash, and watermelon causes the bottom (blossom end) of the fruit to turn brown and rot. Promptly remove affected fruits, and irrigate plants evenly and regularly during dry weather.
• Tomato plants may exhibit symptoms of various leaf spot diseases such as septoria and early blight. Remove lower leaf branches to improve air circulation, as well as any badly-infected lower leaves. Keep a thick organic (biodegradable) mulch around plants, and water around the base of your plants to keep foliage dry.
• Squash vine borer larvae are feed inside squash and pumpkin stems. Monitor plants for signs of wilting and entrance holes on lower stems. You may see sawdust-like frass around the hole. Make a lengthwise slit halfway through infested stems above the entrance hole(s) to locate and remove larvae.
• Brown rot infects peach, cherry, and plum fruits. Pick peaches when their skin background color changes but before fruits become fully ripe. Bring them indoors, submerge them in a 1:10 bleach-to-water solution to kill brown rot fungal spores, rinse well, and allow them to ripen in the kitchen.
• Leave blueberries on the plants for three to five days after they turn blue. This allows berries to reach their maximum sugar content.

• Proper lawn mowing is critical to help it survive the summer. Cut cool-season turf (fescue and bluegrass) to a height of 3 or 4 inches and leave the clippings on the lawn where they will naturally decompose.
• Fertilize bermudagrass and zoysia lawns. Do not fertilize cool-season grasses (fescue and bluegrass) until early autumn.
• Consider planting groundcovers where grass won’t grow, such as in shady areas, around tree roots, and on steep slopes. Select lawn alternative plants based on the amount of sun or shade the site receives, how well the soil drains, and whether they need to be unappealing to browsing deer.

Beneficial insects

• Fireflies are abundant and lighting up the night. As larvae (juveniles), these insects feed on a wide variety of garden pests like slugs and caterpillars. Support these beneficial insects by reducing light pollution, reducing/eliminating pesticide use, and leaving leaf litter in the fall.
• Assassin bugs are active. These insect predators feed on a wide variety of garden pests. Learn to identify common assassin bug species and their different life stages (egg, nymph/immature, adult) so you know to leave them be and conserve their pest control services.
• Mud dauber wasps are active. These solitary wasps are pollinators as adults while feeding on nectar. The adults also collect spiders like black widows to feed to their young. Look for their distinct mud tube nests and leave them be when you can. These wasps do not defend their nests and are not aggressive; rarely sting unless handled or swatted.
• Cicada killer wasps are active. These solitary wasps create underground burrows to rear their young. Adults hunt annual dog-day cicadas to feed their young. Despite their large size, these wasps are not aggressive and rarely sting unless handled or swatted. Male wasps may act defensive around nesting habitat, but they do not have stingers and cannot sting.
• Lacewing adults are abundant. The larvae (juveniles) feed on a wide variety of garden pests. Learn to recognize all life stages (egg, larva, pupa, adult) so you can leave them alone and conserve their pest control services. Support these beneficial insects by reducing light pollution, reducing/eliminating pesticide use, and planting a diversity of flowering native plants.
• Dragonfly and damselfly adults are active. These predators feed on a wide variety of insects including mosquitoes and midges. Their immature (nymphal) stages are aquatic. Support these beneficial insects by conserving ponds and natural wetlands and reducing/eliminating pesticide use.

​​​​​​​​​Pests

• Spotted lanternfly adults may be found feeding on many hosts, especially tree-of-heaven (Ailanthus altissima). If you observe spotted lanternflies, inform the Maryland Department of Agriculture (MDA) by reporting the sighting here. These insects are mainly nuisance pests in residential gardens and landscapes. They have not been shown to significantly damage otherwise healthy ornamental plants.
• Japanese beetle adults may be feeding heavily at this time. Knock the beetles into a bucket of soapy water held underneath foliage or branches. Traps are not recommended: studies show that they can attract more beetles to your landscape, resulting in increased feeding damage.
• Viburnum leaf beetle adults are emerging. Brush the beetles into a bucket of soapy water held underneath viburnum foliage or branches. Fortunately, many predators feed on this pest. Encourage predatory insect activity by reducing/eliminating pesticide use and planting a diversity of flowering native plants. Consider planting viburnum varieties that have shown resistance against this pest.
• Bagworm caterpillars are now very active. Look for little bags crawling around on evergreen trees and shrubs, and be prepared to spray infested shrubs or trees with the biopesticide Bacillus thuringiensis (Bt) by mid-July, following all label instructions. Around late July, bagworms will begin to mature, at which point they are not well-controlled with Bt. Older/larger bagworm caterpillars are best collected by handpicking the bags and placing them in soapy water. If infestations are severe, chemical treatments could be considered and applied after mid-July.
• Scale insects are best controlled during their vulnerable crawler stage (just-hatched juveniles). Some species of scale, like the second generation of euonymus scale, will begin hatching this time of year. Monitor for crawlers, particularly on plants with a history of scale infestation. Specific controls and timing are based on the scale species.
• Colorado potato beetle adults are laying eggs, typically on eggplants, potatoes, peppers, and tomatoes. Look for the eggs and larvae (immatures) and squish them. Any found adults or larvae can be placed into a container of soapy water.
• Harlequin bug adults are laying eggs, typically on crucifers and brassicas. Look for the eggs and hand remove or squish them. Nymphs (immatures) and adults can be placed in a container of soapy water.
• Squash bug adults are laying eggs, typically on cucurbits. Look for and squish any eggs. Nymphs and adults can be placed in a container of soapy water.
• Squash vine borer adults are laying eggs. Cover squash with floating row covers or insect mesh netting until they flower; remove covers during flowering to allow for pollination. Monitor for squash vine borer entry holes and frass (fecal matter). Infected plants may be saved by carefully slicing the stem lengthwise and removing larvae, then placing moist soil over the split to encourage rooting. Remove and destroy any plants killed by squash vine borers.
• Mosquitoes are active. Patrol your yard at least twice a week, removing any standing water from trash and recycling cans, flowerpot saucers, child and pet toys, wading pools, tires, tarps, or plastic sheeting. It only takes one teaspoon of water for some mosquito species to reproduce. Clean gutters and cover corrugated drain pipe openings with a piece of mesh or pantyhose secured with a rubber band, or replace it with a smooth drain pipe that will not hold water.
• Ticks are becoming more active and can carry serious diseases that affect humans and pets. Wear light-colored long pants, long sleeves, and close-toed shoes. Tuck pants into socks, and tuck shirts into pants, to keep climbing ticks visible for prompt removal. Use insect repellent (age-dependent; check the label for safe use), after putting on sunscreen. Shower and check for ticks after being outdoors.

• Southern blight, a significant soil-borne fungal disease, thrives in hot and humid weather. It can affect a wide range of annuals, groundcovers, and perennials, including thyme, coneflower, coreopsis, and black-eyed Susan. Affected lower stems turn brown or black, foliage wilts, and plants will eventually dry up and die.
• Bacterial and fungal leaf spots can appear on various trees, shrubs, vines, and perennials with the increase of hot and humid weather, especially after rain or leaf-wetting irrigation. Two commonly-affected plants are hydrangea and black-eyed Susan. Leaf spots are mostly a cometic issue and usually do not seriously threaten plant health. Discourage infection by improving air circulation around foliage and avoid wetting leaves when watering. Remove dead and fallen leaves after autumn freezes so fewer spores overwinter around the base of the plant.
• Powdery mildew affects the leaves of trees, shrubs, annuals and perennials, and outbreaks can occur in summer when warm, humid weather is followed by cooler nights. This fungal disease is mostly a cosmetic problem, but can cause leaf distortion, yellowing, browning, and premature shedding. Powdery mildew on flower buds can also affect blooms. Grow mildew-resistant varieties when possible, and improve air circulation to keep leaves drier by thinning crowded plants or stems.
• Beech Leaf Disease (BLD) causes significant decline, dieback, and the eventual death of beech trees. It is now present in most counties in Maryland. Foliage symptoms include dark bands between the leaf veins (when viewed from below or backlit), as well as leaf thickening and distortion.

• Continue to fertilize indoor plants since they are actively growing.

• Three different types of crickets may invade homes in Maryland. Camel crickets look the most unusual because of their humped back. They are often found in damp basements. Keep them out by sealing foundation cracks and fixing door weather-stripping.
• Springtails are very small insect relatives, 1 to 2 millimeters long, and often whitish, tan, or grayish in color. Occasionally they may be abundant in areas of high humidity, such as bathrooms, kitchens, and basements.
• House centipedes are very common and can be found quickly moving across floors, walls, or ceilings. They are harmless and do not damage buildings. House centipedes feed on other arthropods in and around the home/building. If found in high numbers, it may indicate there are high numbers of other arthropods in the building that the centipede is feeding on. If centipedes are found, vacuum them up or utilize sticky traps.
• Earwigs are commonly found indoors during high outdoor temperatures. They prefer moist conditions and are attracted to lights. Earwigs do not cause damage to buildings. If a few earwigs are found, they can be removed by vacuuming or using sticky traps. High numbers of earwigs could indicate there is a moisture issue inside or near the building, or an access point (worn-down weather-stripping on a door or window, for example) that needs to be sealed. 
• Phorid flies and fungus gnats are attracted to moist and/or decaying organic matter, including potted plants, leaking sewage pipes, pet waste, rotting fruits and vegetables, garbage disposals, dirty mop heads, and compost bins. These flies do not bite. Look inside and around the home/building for possible attractants. Sticky traps could also be used to locate fly breeding sites.
• Fruit flies are typically found in the kitchen where they are attracted to overripe or rotting produce. Fruit flies do not bite. Remove any spoiled food and seal any open containers of food to reduce attractants. With high numbers of flies, thoroughly clean the kitchen/area, including the fridge, garbage disposal, and pantry, along with removing any trash, compost, and recycling. Commercial or homemade fruit fly traps can also be used.
• Artificial light sources at night will attract many different arthropods, some of which could end up inside a building if there are any entry points near the light source such as open windows, doors, cracks, and crevices. Consider closing blinds or shades at night and opting for motion-activated outdoor lighting to reduce unwanted arthropods and to protect nocturnal beneficial insects like fireflies. (Artificial light sources are a fatal attraction to many beneficial insects.)