Gardening by Month - July

Trees & Shrubs

• Powdery mildew is unsightly on lilacs but rarely harmful. Shrubs grown in full sun are less prone to this disease.

• Remove infected leaves from roses and clean up any infected leaves that have fallen. If needed, continue spraying roses with a preventative fungicide for black spot. 

• Prune climbing roses and rambler roses after blooming if the plants are two years or older.

• Newly planted trees and shrubs should continue to be watered thoroughly. 

• Japanese beetles are usually active at the beginning of the month and then taper off. 

• Mid to late July, guignardia blotch of horse chestnut may start showing symptoms. No control is needed as damage occurs late in the season.

• Lace bugs may still be feeding on azaleas, however, control methods have little effect at this time of year. Take note of infested plants to plan a treatment in the following year. 

• Holly leaf miner larvae may be feeding this month, however, insecticides may not be effective at this time.

• Apply final treatment for borers on hardwood trees.

• Do not fertilize trees & shrubs after July 4^th. Fertilizing late may cause lush growth that is susceptible to winter kill. 

• Fall webworms begin nest building near the ends of branches of infested trees this month. Pruning is not required but can help control, as well as using a BT spray if defoliation becomes severe. 

• Semi-hardwood cuttings of spring flowering shrubs can be made now.

• Summer pruning of shade trees can be done now.

Annuals & Perennials

• Some plants are susceptible to powdery mildew (phlox & peonies), spray with preventative fungicides before a rain.

• To keep container-planted annuals in bloom and vibrant, fertilize regularly in accordance to the label instructions. 

• By early to mid-July, iris borer larvae have started to bore into the rhizomes where they will grow then exit in late July - early August to pupate in the soil. 

• Keep deadheading spent flowers for continued bloom. Cut back to where the flower stem meets the rest of the plant to keep a tidy appearance.

• Plant zinnia seeds by July 4^th for a late bloom in the fall. 

• Crown rot of perennials is prominent when temperatures are 85-95^oF for several days with intermittent rains. Be sure to use sterile practices when removing the plant and excavating the soil. 

• Bearded irises can be divided now if needed (most should be divided every 3-5 years). 

• Don't pinch back mums after mid-July or you may delay flowering.

• The second generation of phlox bugs may be present at this time. Prune off badly infested foliage and dispose. 

Lawn

• Water frequently enough to prevent wilting. Early morning irrigation allows the turf to dry before nightfall, reducing the chance of disease.

• Monitor lawns for newly hatched white grubs. If significant damage is occurring (or if you find more than 1o grubs per square foot of turf), apply appropriate control.

Fruits & Vegetables

• Blossom-end rot of tomatoes, peppers, and cucurbits occurs when soil moisture is inconsistent. Ensure even soil moisture, applying a 2-3 inch layer of mulch will help.

• Dig up potatoes when the foliage dies down. Plant fall potatoes by mid-July. 

• Broccoli, cabbage, and carrot seeds can be directly sown starting in mid-July. Keep well-watered in times of heat, and give shade on the hottest of days. 

• Sweet corn is ripe when the silks turn brown

• Tomatoes may be showing damage from several fungal and bacterial diseases: septoria leaf spot, early blight, fusarium wilt, verticillium wilt, late blight, and mosaic virus. Tomato hornworms may also be found munching on foliage. 

• Some abiotic problems of tomatoes may be controlled, such as heat stress, but others can be prevented, such as sunscald. 

• Cucurbits, tomatoes, and peppers may have pollination issues during this month. Tomatoes and peppers cannot set fruit when daytime temperatures exceed 90^oF. During high humidity, cucurbit pollen becomes sticky and does not transfer well. 

• Be sure to keep cucumbers well-watered as drought conditions can cause bitter fruit. 

• Harvest onions and garlic when the lower third of the foliage has turned yellow/brown. Let onions and garlic cure for at least two weeks before consuming. 

• Squash vine borer adults may still be emerging this month. Damage may also start showing up this month. 

• Cover grape clusters loosely with netting to provide some protection from animals and birds.

• Prune out and destroy old fruiting canes of raspberries after harvesting. Leave canes that did not fruit that year as they will fruit the following year.

• Blackberries and thornless blackberries are ripening now. 

• Early peach varieties are ripening now.

• Peachtree borer adult moths may be active during this time.

• Cucumber beetles can transmit bacterial wilt to other cucurbits, especially young plants which can then easily die.

Miscellaneous

• Be sure to keep all new plantings thoroughly watered, especially during times of drought to avoid water stress. Heat stress can also be prevalent during this month.

• To keep weeds at bay, be sure to keep plants from making seeds. Manually remove or use an appropriate herbicide.

• Hot and dry weather is ideal for spider mite development. Damage appears as stippling on the leaves, yellowing leaves, and thin webbing. 

• Annual cicadas start appearing this month.

• Monitor plants for leafhoppers. Control is rarely needed and is usually difficult as the insects are highly mobile. Sticky traps and insecticidal soap may be effective as needed.

• Galls may be noticeable on various plants such as oaks, hackberry, and witch hazel. Galls are a normal part of plants and usually do not harm plants. Eriophyid mites are commonly responsible for these galls and do not require any control.