Oregon State University Extension Service

July garden calendar

Recommendations are not necessarily applicable to all areas of Oregon. For more information, contact your local Extension office.

The Oregon State University Extension Service encourages sustainable gardening practices.

We emphasize preventive pest management over reactive pest control. Identify and monitor problems before acting and opt for the least toxic approach that will remedy the problem. Favor biological control agents (predators, parasitoids) over chemical controls.

Maintenance and cleanup

  • If you want a green lawn, water frequently during periods of heat and drought stress. Irrigate a quarter inch four to six times per week from June through August. Measure your water use by placing an empty tuna can where your irrigation water lands.

  • Mound soil up around the base of your potato plants. Gather and eat a few "new" potatoes from each hill when plants begin to flower.

  • To reduce evaporation, water vegetable and flower gardens in the early morning. Water the soil rather than leaves to reduce disease. Water deeply and infrequently to encourage root growth.

  • Pay careful attention to watering and feeding hanging baskets of flowers or vegetable plantings during extended periods of hot weather.

  • Weed and fertilize rhubarb and asparagus beds. A mulch of compost or rotted cow manure works well as fertilizer. Water deeply to develop crowns for next year.

    • Mulch with paper, plastic, sawdust, etc. to conserve soil moisture.

    • Stake tall-growing flowering plants such as delphinium, hollyhocks, and lupine. Stake tomatoes as necessary.

    • Make compost of lawn clippings and garden plants that are ready to be recycled. Do not use clippings if lawn has been treated with herbicide, including "weed-and-feed" products. Do not compost diseased plants unless you are using the "hot compost" method (120 degrees to 150 degrees F).

    Planting and propagation

    • Beets, bush beans, carrots, cauliflower, broccoli, lettuce, kale and peas planted in midsummer provide fall and winter crops. Get more tips on what to plant now in Fall and Winter Vegetable Gardening in the Pacific Northwest.

    • Dig spring bulbs when tops have died down; divide and store or replant.

    • Oregon Coast: First planting of Chinese cabbage, kohlrabi, and rutabagas.

      Pest monitoring and management

      Use chemical controls only when necessary and only after thoroughly reading the pesticide label. Consider cultural controls first, then physical and biological controls. Choose the least-toxic options (insecticidal soaps, horticultural oils, botanical insecticides, and organic and synthetic pesticides), and use them judiciously.

      • Control hollyhock rust by sanitation, picking affected leaves, or spraying with a registered fungicide. Read and follow label directions.

      • Watch for cutworm damage in garden. In July, climbing cutworms become a problem and large portions of foliage will begin to disappear on established plants. Use barriers, remove by hand, use beneficial nematodes when soil temperature is above 55 degrees F, or spray with Bt-k according to label directions.

      • Late July: Begin to monitor for early and late blight on tomatoes. Correct by pruning for air circulation, picking off affected leaves, and/or treat with approved fungicide. See this article for more information on common tomato problems.

      • Place traps to catch adult apple maggot flies. You can use pheromone traps to monitor presence of pests.

      • July 10: Spray filbert trees for filbertworm, as necessary.

      • July 10-15: Spray peach and prune trees for peach tree borer and peach twig borer, as necessary.

      • July 17-23: Third spray for codling moth in apple and pear trees, as necessary.

      • Cover blueberry bushes with netting to keep birds from eating the entire crop.

      • Monitor camellias, holly and maple trees for scale insects. Treat if necessary.

      • Monitor rhododendrons for adult root weevils. Look for fresh evidence of feeding (notching). Try sticky trap products on plant trunks to trap adult weevils. Manage root weevils with beneficial nematodes (if soil temperature is above 55 degrees F). If root weevils are a consistent problem, consider removing plants and choosing resistant varieties.

      • Spider mites can become a problem on ornamental plants, vegetables and fruit plants during hot, dry weather. Watch for dusty-looking foliage, loss of color and the presence of tiny mites. Wash infested areas with water or spray with appropriate pesticides. For more information visit the PNW Insect Management Handbook Landscape Pests - Spider Mites.

      • East of the Cascades: If necessary, spray for corn earworm as silking begins. Protect bees from spray.

      • Continue monitoring raspberry, blackberry, blueberry, cherry and other plants that produce soft fruits and berries for spotted wing drosophila. If the flies are present, use an integrated and least-toxic approach to manage the pests. Learn how to monitor for drosophila flies and larval infestations in fruit.

      • Check leafy vegetables for caterpillars. Remove caterpillars as they appear. Use Bt-k, if necessary.

      • Remove cankered limbs from fruit and nut trees for control of diseases such as apple anthracnose and bacterial canker of stone fruit. Sterilize tools before each new cut.

      Trade-name products and services are mentioned as illustrations only. This does not mean that the Oregon State University Extension Service endorses these products and services or intends to discriminate against products and services not mentioned.

      Source URL: https://extension.oregonstate.edu/gardening/techniques/july-garden-calendar