Gardening by Month - July
Monthly Tips and Tasks

Category
 
Week
 
Activity 
  1 2 3 4  
 Ornamentals     x x x x Provide water in the garden for the birds, especially during dry weather.
  x x x x Remove infected leaves from roses. Pick up fallen leaves. Continue fungicidal sprays as needed.
  x x x x While spraying roses with fungicides, mix extra and spray hardy phlox to prevent powdery mildew.
  x x x x Newly planted trees and shrubs should continue to be watered thoroughly, once a week.
  x x x x Fertilize container plants every 2 weeks with a water soluble solution.
  x x x x Keep weeds from making seeds now. This will mean less weeding next year.
  x x x x Keep deadheading spent annual flowers for continued bloom.
  x x x x Perennials that have finished blooming should be deadheaded. Cut back the foliage some to encourage tidier appearance.
  x x     Plant zinnia seed by July 4th for late bloom in annual border.
  x x     Spray hollies for leaf miner control.
  x x     Prune climbing roses and rambler roses after bloom.
  x x     Apply final treatment for borers on hardwood trees.
  x       Apply no fertilizers to trees and shrubs after July 4th. Fertilizing late may cause lush growth that is apt to winter kill.
  x       Hot, dry weather is ideal for spider mite development. With spider mite damage, leaves may be speckled above and yellowed below. Evergreen needles appear dull gray-green to yellow or brown. Damage may be present even before webs are noticed.
    x x   Fall webworms begin nest building near the ends of branches of infested trees. Prune off webs. Spray with Bt if defoliation becomes severe.
    x     Divide and reset oriental poppies after flowering as the foliage dies.
      x x Semi-hardwood cuttings of spring flowering shrubs can be made now.
      x x Summer pruning of shade trees can be done now.
      x   Powdery mildew is unsightly on lilacs, but rarely harmful. Shrubs grown in full sun are less prone to this disease.
        x Divide bearded iris now.
     x     Don't pinch mums after mid-July or you may delay flowering.
 Lawns x x x x Water frequently enough to prevent wilting. Early morning irrigation allows turf to dry before nightfall and will reduce the chance of disease.
      x x Monitor lawns for newly hatched white grubs. If damage is occurring, apply appropriate controls, following product label directions.
 Vegetables x x x x Blossom-end rot of tomato and peppers occurs when soil moisture is uneven. Water when soils begin to dry; maintain a 2-3 inch layer of mulch.
  x       To minimize insect damage to squash and cucumber plants, try covering them with lightweight floating row covers. Remove covers once plants flower.
    x     Dig potatoes when the tops die. Plant fall potatoes by the 15th.
      x x For the fall garden, sow seeds of collards, kale, sweet corn and summer squash as earlier crops are harvested.
      x x Set out broccoli, cabbage, and cauliflower transplants for the fall garden.
      x   Sweet corn is ripe when the silks turn brown.
      x   Keep cukes well watered. Drought conditions will cause bitter fruit.
      x   Harvest onions and garlic when the tops turn brown.
       

 x 

Sow seeds of carrots, beets, turnips, and winter radish for fall harvest.
  x x x x Cover grape clusters loosely with paper sacks to provide some protection from marauding birds.
  x       Prune out and destroy old fruiting canes of raspberries after harvest is complete.
  x       Blackberries are ripening now.
    x x   Apply second spray to trunks of peach trees for peach borers.
      x x Early peach varieties ripen now.
        x Thornless blackberries ripen now.
July Pests and Problems


Continue to monitor for plant bugs on phlox and treat if required. Mildew is another common problem of phlox. Aster yellows is distinctive and can affect many different plants.
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Phlox Bugs
Phlox bug damage (Hemiptera) on phlox (Phlox
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Powdery Mildew - Outdoors
Powdery mildew on phlox (Phlox
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Aster Yellows
Extreme leafy growth from flower of black-eyed Susan (Rudbeckia) caused by aster yellows 

Mildew on lilacs is common but rarely requires treatment. Check iris for iris borers and perennials for southern blight.
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Powdery Mildew - Outdoors
Powdery mildew on lilac (Syringa
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Iris Borer
Larva of iris borer (Lepidoptera) tunneling in iris rhizome (Iris
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Crown Rot of Perennials (Southern Blight)
Southern blight causing collapse of hosta (Hosta

Continue to monitor for black spot on roses and treat as required. Also continue to monitor lace bugs on azaleas. Treating this late in the season, however, may have little value. In following years learn how to detect them earlier and treat them.
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Black Spot of Rose
Yellowing rose (Rosa) leaves with black spots are characteristic of black spot of rose 
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Lace Bugs
White flecking on upper leaf surface on azalea (Rhododendron) caused by feeding of lace bugs (Hemiptera); heavy infestation 
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Lace Bugs
Adult oak lace bug (Hemiptera ) on underside of bur oak leaf (Quercus macrocarpa

Be alert to the flight of peachtree adults that are active from July - September. See August and May for control measures.Monitor plants for leafhoppers.
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Peachtree Borer
The caterpillars/larvae of peachtree borers (Lepidoptera) dug from the roots and crown of a peach tree (Prunus
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Leafhoppers and Planthoppers
Leafhopper nymph (Hemiptera) on squash (Cucurbita) leaf 
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Leafhoppers and Planthoppers
The damage on this silver maple leaf (Acer saccharinum) is typical of feeding by leafhoppers (Hemiptera) but it could be caused by a true bug 

If you are treating grubs with Merit, do so early in the month as it takes several weeks to be effective. Many galls affect the leaves of trees and shrubs and do little if any damage.
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Grubs in Lawns
Grubs (Coleoptera) can be found when the grass killed by their feeding is pulled back. 
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Gall-forming Eriophyid Mites
Eriophyid mites (Acari) are responsible for many galls, like these galls on the males flowers of an ash (Fraxinus
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Galls on Trees
This gall on an oak leaf (Quercus) looks like an oak flake gall caused by a wasp (Hymenoptera) but dissecting the gall is the only sure way to tell what caused the gall 

Blossom-end rot of tomatoes and vine crops is a common occurrence as summer gets into full swing. Control squash vine borers early before they do serious damage.
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Blossom End Rot of Tomato and Pepper
Blossom-end rot on tomato fruit (Lycopersicon
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Blossom End Rot of Cucurbits 
Blossom-end rot on pumpkin (Cucurbita) fruit 
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Squash Vine Borer
The rotted crown of this summer squash plant (Cucurbita) was caused by squash vine borers (Lepidoptera) 

Other tomato problems to be aware of and treat if necessary are septoria leaf spot, early blight, and spider mites, which affect many plants.
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Septoria Leaf Spot of Tomato
Spots on tomato leaf (Lycopersicon) caused by septoria leaf spot 
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Early Blight of Tomato
Early blight on tomato leaf (Lycopersicon
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Spider Mites - Outdoors
A heavy spider mite infestation (Acari) caused the curling, distortion, yellow patches and bronzed patches on the leaves of this tomato plant (Lycopersicon

Common problems of cucumbers, melons, and other cucurbits this time of year include bacterial wilt, cucumber beetles, and pollination problems.
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Bacterial Wilt of Cucumber
Collapsed cucumber plant (Cucumis) caused by bacterial wilt 
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Cucumber Beetles
Adult twelve-spotted cucumber beetle (Coleoptera) 
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Pollination Problems of Cucurbits
Poor pollination can cause cucumbers (Cucurbita) to be misshapen and stunted. 

Very common problems of plants during the heat of the summer are drought, scorch, and heat stress. During dry spells water as needed. Plants that regularly scorch even when given ample water may benefit by being relocated to a more shaded location. In mid- to late summer fall webworms may also be seen.
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Drought and Water Stress
Close-up of drought stress on magnolia (Magnolia
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Scorch, Sunburn, and Heat Stress
Scorch on dogwood (Cornus) leaves 
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Fall Webworm
Fall webworm (Lepidoptera) on crabapple (Malus

Watch for signs of oak wilt and be prepared to remove roses that are affected by rose rosette. Apple scab is a common fungal disease of apples that results in yelllowing and dropping leaves.
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Oak Wilt
Oak (Quercus) dying from oak wilt 
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Rose Rosette
Symptomatic thorns on rose (Rosa) caused by rose rosette 
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Apple Scab
Yellowing leaves and spots caused by apple scab on crabapple (Malus

If holly leafminer has been a problem in the past, spray in the first two weeks of July with a registered insecticide for control.
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Holly Leafminer
Tunneling damage in holly (Ilex) leaf caused by holly leafminer, a fly maggot (Diptera) 
 
 

Japanese beetles will continue to cause damage the first part of the month but will then taper off. Verticillium wilt is a destructive wilt that can quickly kill many tree, shrub, and herbaceous plant species.
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Japanese Beetle
Japanese beetles (Coleoptera) feed on over 300 species of plants 
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Verticillium Wilt
Redbud (Cercis) wilted and died within a week from verticillium wilt 
 

Cicadas start appearing this month.
 
 
 

Reduce problems with weeds by keeping them from making seeds by cutting or pulling before they flower.