July Garden Calendar

Trees & Shrubs

As weather becomes hot and dry, deeply water any trees or shrubs that have been planted within the past year. Prune all dead, damaged, or diseased branches any time of the year.

July is the last month for a while to prune most shrubs, including aucuba, azalea, barberry, boxwood, cherry laurel, euonymous, forsythia, fothergilla, jasmine, leucothoe, lilac, nandina, osmanthus, photinia, pieris, privet, rhododendron, viburnum, weigela, witchhazel and yew.

July is the last month for a while to prune deciduous trees such as buckeye, flowering cherry, crabapple, dogwood, fringetree, hawthorn, magnolia, maple, black gum, peach, pear, plum, and redbud.

And it is the last month to prune Leyland cypress, hemlock, and arborvitae. Remove dead and broken branches. If the tree has more than one leader growing at the top, prune to a single leader. For other limbs, do not prune into wood that has no needles.

Diseases and Pests that Commonly Occur in July
Eriophyd Mite Gall
Causes the damage we see locally is usually leaf and bud galls on black gum, caryopteris (or bluebeard), and maple. The mites cause deformities in leaf, bud and twig growth. Some cause blisters, some rust spots, and others witches broom.

Fire Blight
attacks apple, pear, quince, pyracantha, cotoneaster, mountain ash, hawthorn, and raspberry. Locally, it is a severe problem of pears. The disease usually begins in the spring with an infection of blossoms and new shoot growth. Leaves initially turn a dark green or gray green, then rapidly change to brown then black. Blackened twigs look as though they were burnt in a fire. The infection moves down the twigs and into branches. If the infected branches are not removed, the plant will eventually die.

Japanese Beetles
begin hatching in late June and feed and lay eggs until early August. They are easily recognized by their bottle green color and coppery wings. Beetles feed on a wide range of plants, including leaves, flowers, and over ripe fruit.

Phyllosticta Leaf Spot on Maples
and others starts as brown spots on leaves that enlarge, with centers becoming tan in color. Edges of the spots have purple or red rims, hence the other common name, purple-eye leaf spot. Sometimes spots merge and centers fall out creating ragged holes in the leaf. Some leaf drop may take place when there is extensive infection. However, new leaves grow in summer to replace those lost in spring.

Rust on Hollyhocks
typically appears as small, bright orange, yellow, or brown pustules on the underside of leaves. Like many fungal diseases, rust is worse when weather is moist. In recent years, we have seen rust on hollyhock, beans and many other species.

Shot Hole Disease
on laurels causes holes in leaves of various sizes, and sometimes leaf margins that appear ‘scooped out’. This disease is caused by a combination of the bacteria Xanthomonas arboricol pv. pruni and/or Pseudomonas syringae and several fungal pathogens, including Cercospora species. Both fungal and bacterial pathogens can be present on the plant at the same time. The disease begins as circular leaf spots, usually red, brown or wet looking. Centers turn tan before dropping out. These holes and notched edges can easily be mistaken for chewing insect damage. You may also see stem cankers.

Sooty mold
appears as a black coating on leaves and stems. It grows on honeydew, secreted by a sucking insect pest, and will usually stop once the insect problem is corrected.

Root Rot
is generally indicated by severe wilting of the plant. Often the plant is located in a wet area that promotes growth of fungal and fungal-like pathogens.

For more information on pests and diseases of July go to July Lab Report


If your cool season grass is not growing, don’t mow it.

This is the time of year to raise the cutting height on your lawn mower for cool season grasses. Three inches or higher is a good cutting height for Kentucky bluegrass perennial ryegrass and tall fescue.

Warm season grasses love the hot weather. Mow zoysiagrass and bermudagrass to 1-2 inches.

Use a mulching mower, and leave the clippings on the lawn to return nutrients to the soil.

Cool Season Grasses (fescues, bluegrass, ryegrass)
Blistering hot weather followed by afternoon thunderstorms is a formula for disaster. If your soil is compacted or has a low pH, your lawn is probably showing signs of strain. This is a good time to do a soil test. Remember to aerate in late summer or fall.

Check for lawn diseases if you see brown patches, brown rings, or cottony white growth on your lawn. This may indicate Leaf Spot, Dollar Spot, or Brown Patch disease. Bring samples of healthy and diseased grass to a FCMGA plant clinic, located at Fairfax County farmers’ market and selected libraries, for diagnosis and recommended treatment.

Mid-July to mid-August is time to treat for white grubs. If you suspect there is a grub problem, (many Japanese beetles in your yard is usually a good indication), use a spade to remove a square of turfgrass a foot long and wide and 1-2 inches deep. If you count six to 10 grubs in the soil, you should consider treating for grubs. However, remember that insecticides harm beneficial insects as well as pests. Use a product that is labeled to control white grubs and follow label directions.

Take care in applying selective weed-killers in hot weather because they may damage the turfgrass and surrounding plants. It is best to wait until cooler weather in the fall to apply broadleaf weed-killers safely.

If the weather becomes dry in July, irrigate at the rate of one inch of water per week in the early morning to maintain green. Infrequent, deep water is best. The water should penetrate to a depth of 4-6 inches. If you choose not to irrigate and allow the lawn to go dormant, it will likely green up again in September.

Do not fertilize this month.

Warm Season Grasses (zoysiagrass, bermudagrass)
The cold winter may have damaged these grasses, but the hot weather in June has allowed most to recover. If your warm season grass has not fully recovered, this is the time to cultivate, dethatch, fill bare spots, or plant an entire lawn of warm season grasses. Early July is also time to begin your fertilization program. Apply 0.5-1 pound of water soluble nitrogen per 1000 square feet every three to four weeks, not to exceed 2.1 pounds of nitrogen total.

Vegetable Garden

Harvesting of many crops should begin this month.

Plan now for the fall vegetable garden because some of it must be planted in early July. Some crops, however, can wait until August. Planning should take into account the first frost date in the fall where you live. In Fairfax County, the first frost on the east and south side of I 395 and the I 95 corridor occurs sometime between November 8 and November 28; on the north and west, between October 19 and October 29. This gives a growing season of approximately 105 days to the east and south of the dividing line and 90 days to the north and west. Providing about a week for seeds to germinate at the beginning and about 2 weeks for harvest at the end, select vegetables that mature within the remaining timeframe.

Warm season vegetables such as beans can be planted in July for harvest in September or October. Cool season vegetables such as broccoli and cabbage can be planted in late July or early August.

Depending on the variety, lettuce, which may be planted in late July, may need to be started indoors because the seeds will not germinate when soil temperatures exceed 85 degrees F.

Pick cucumbers early and often; they don’t last well on the vine. Keep them consistently watered to prevent a bitter taste.

Pumpkin and squash blossoms are edible. Pick them as soon as they open. Wash them well; dip them in batter and deep fry.

Pinch off vine crops at the growing tips to prevent them from taking over the entire garden. This will also direct the plant’s energy to produce fruit.

If your tomatoes stop setting fruit, it is likely because daytime temperatures exceeded 86 degrees F and nighttime temperatures exceeded 70 degrees F several days in a row. The flowers abort in these warm conditions. There is nothing you can do about it. Tomatoes taste best when they are eaten within minutes of being picked. Taste goes downhill in a hurry when tomatoes are refrigerated.

If birds are pecking holes in your tomatoes, try picking the tomatoes just as they begin to turn pink. These tomatoes are known as “breakers.” You can also slip an old nylon stocking over an entire cluster of tomatoes when they are green; tie a knot at the end of the stocking. When the tomatoes ripen, remove the stocking and put it over another green tomato cluster.

If you use overhead watering, water your vegetable garden early in the morning to allow the leaves of the plants to dry off quickly. It is better to use drip irrigation or to hand water the plants, taking care not to wet the foliage.

Diseases and Pests that Commonly Occur in July
Downy Mildew
indicated by gray fuzz on the underside of basil leaves and leaves of cucurbits.

Septoria Leaf Spot and Early Blight on Tomatoes
characterized by small brown spots on the leaves. Early Blight is indicated by large spots that coalesce into purple blotches.


Although most pruning of fruit trees is done during the dormant season, summer pruning of fruit trees may be done to achieve optimum form or size. This is a good time to remove suckers. The center of the tree should be pruned to keep it open to air circulation and sunlight.

Maintain good sanitation practices. Remove and dispose of fallen fruit and leaves.

For strawberries and blueberries, make sure to keep up with weeding.

Flowering Annuals, Perennials

Remove spent flowers of cosmos, zinnia, marigold, scabiosa, and others to maintain plant vitality and keep them flowering. Before using any pesticide, make sure you have properly identified the disease or pest. FCMGA plant clinics and the Diagnostic Lab are at your service for this purpose.
A Guide to Successful Pruning, Shrub Pruning Calendar, VCE Publication 430-462
A Guide to Successful Pruning, Deciduous Tree Pruning Calendar, VCE Publication 430-460
A Guide to Successful Pruning, Evergreen Tree Pruning Calendar, VCE Publication 430-461
Mowing To Recycle Grass Clippings: Let the Clips Fall Where They May, VCE Publication 430-402
Maintenance Calendar for Cool-Season Turfgrasses in Virginia, VCE Publication 430-523
Maintenance Calendar for Warm-Season Lawns in Virginia, VCE Publication 439-522
Spring and Summer Lawn Management Considerations for Cool-Season Turfgrasses, VCE Publication 430-532
Vegetable Planting Guide and Recommended Planting Dates, VCE Publication 426-331
July Tips, Vegetables, VCE Publication
Annuals: Culture and Maintenance, VCE Publication 426-200
Tree Fruit in the Home Garden, VCE Publication 426-841
Small Fruit in the Home Garden, VCE Publication 426-840
July Tips, Lawns and Landscaping, VCE Publication
Tomato Questions, Texas A&M Extension Publication