Marin Master Gardeners
University of California
Marin Master Gardeners

Gardener's checklist for summer

What to do in your garden in the summer

JULY

  • Monitor soil moisture. The water requirements of your plants peak in July. Established perennials, shrubs and trees need infrequent but deep watering. Container plants may need daily watering.
  • Pick up fallen fruit to discourage fungal growth and pests.
  • Control powdery mildew, a fungus that likes dry summer conditions. Spray susceptible plants with a horticultural oil or biological fungicide. Follow package directions. 
  • Drain standing water from container saucers to eliminate mosquito breeding grounds.
  • Pinch off spent flowers on perennials and annuals to encourage repeat bloom.
  • Pinch back chrysanthemums to encourage branching and increased bloom. Leggy impatiens and coleus also benefit from being pinched back.
  • Harvest vegetables promptly for continued production.
  • Cut spent berry canes to the ground. Fertilize new canes.
  • Dig up and divide overcrowded bearded irises. 
  • Dig up overcrowded bulbs after the foliage dies. Store in a cool, dry place for replanting in fall.
  • Feed azaleas, camellias and rhododendrons with a balanced fertilizer formulated for acid-loving plants.
  • Feed container plants.
  • Feed citrus.
  • Sow seeds of summer and fall-blooming annual flowers directly in the ground. Cosmos, bachelor buttons, sunflowers, nasturtiums and zinnias are easy and fast to grow from seed. Keep the seed bed moist. 
  • Sow seeds of beets, carrots, greens (collard, mustard, etc.), lettuce, summer and winter squash, and turnips.
  • Transplant starts of broccoli, Brussels sprouts, cabbage and cauliflower.
  • For indoor arrangements, cut flowers in the morning when they are freshest.

AUGUST

  • Monitor soil moisture. Established perennials, shrubs and trees need infrequent but deep watering. Container plants may need daily watering.
  • Pick up fallen fruit to discourage fungal growth and pests.
  • Monitor for spider mites by looking for fine webbing on plants. Minimize the chance of infestation by rinsing dust and dirt off leaves with a spray of water.
  • Manage yellow jackets by setting out traps. Follow package directions. 
  • Attach bands of corrugated cardboard around apple tree trunks to trap codling moth larvae.
  • Pinch off spent flowers on perennials and annuals to encourage repeat bloom.
  • Prune hydrangeas after blooms fade.
  • Feed azaleas, camellias and rhododendrons with a balanced fertilizer formulated for acid-loving plants.
  • Feed container plants.
  • Feed citrus.
  • Harvest vegetables promptly for continued production.
  • Transplant starts of broccoli, cauliflower and Chinese cabbage.
  • Sow seeds of beets, carrots, lettuce, peas, radish and turnips for fall harvest.
  • Order spring-blooming bulbs for best selection.

SEPTEMBER

  • Reduce irrigation times as day length shortens and plant growth slows.
  • Harvest vegetables promptly for continued production. 
  • Compost disease-free annuals and vegetables that have finished producing.
  • Buy bedding plants for fall color, including annual cosmos, snapdragons and zinnias, and perennial asters, chrysanthemums and salvias.
  • Renovate your lawn by seeding bare spots, dethatching and fertilizing. Consider reducing your lawn area.
  • Divide overgrown perennials as they finish blooming. Before replanting them, weed and amend garden beds.
  • Give citrus their last feeding of the year. 
  • Feed azaleas, camellias and rhododendrons with a 0-10-10 fertilizer.
  • Add two inches of compost to the top eight inches of soil for fall and winter vegetables and annuals.
  • Plant ornamental grasses, shrubs, perennials, evergreens and groundcovers.
  • Transplant starts of cabbage and cauliflower. Plant artichoke rootstock.
  • Sow seeds of fava beans, leeks, peas, radish, spinach and turnips.
  • Harvest herbs and dry them for winter use. Make pesto with basil, cilantro or parsley and freeze in small batches.
  • Cut strawflowers, statice, yarrow and other flowers that preserve well. Hang them to dry for use in arrangements.
  • Collect your own seed and store in a cool, dry place, along with any leftover seed packets.
  • Shop for bulbs at local nurseries.


Contributors: Faith Brown, UCCE Placer County Master Gardeners

Resource: Northern California Gardening: A Month-by-Month Guide by Katherine Grace Endicott

Webmaster Email: banielsen@ucanr.edu