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Summer Garden & Landscape Checklist

June / July / August

General Tasks

Clean-up: Mummies, fallen fruit, leaves and nuts to discourage fungal growth and pests.

Compost: Turn compost and keep it as moist as a wrung-out sponge. Add garden waste, grass clippings, pruning material and leaves so long as they are not diseased.

Irrigation: Adjust watering schedules monthly, according to the weather and changing needs of your plants. The water requirements of your plants peak in July and are high in August. Pay close attention to the moisture needs of new plants in your garden. Established perennials, shrubs and trees need infrequent but deep watering.

Mulch: Apply 2-3” of mulch where existing mulch is thin or soil is bare, to protect against heat and water stress in growing roots. Keep mulch back 12” from tree trunks and 6” from perennials to discourage pathogens.

Soil: Apply 1” of compost around landscape plants and work in lightly, followed by a layer of mulch.

Tools: Sharpen pruning shears and other garden tools, as needed. Clean and disinfect your pruning shears after use. Finish with a light coat of oil to protect the blades.

Water: To reduce evaporation, water when temperatures are cooler and air is still, usually in the early morning. Water deeply to moisten the root zone, but no deeper. Container plants may need daily watering, as soil in pots can dry out quickly and damage plant roots on hot summer days.

Weeds: Manage weeds using nonchemical methods such as cultivation, hand weeding, or mowing; use toxic chemicals as a last resort.


Feed Plants:

  • Acid-loving fruits – Use an acid fertilizer; follow application rate for your product. (Blueberries require two applications in summer.)
  • Citrus – Test soil. As needed, apply fertilizer high in nitrogen and/or supplement with iron. (June)
  • Caneberries and deciduous fruit trees (two applications in summer).
  • Vegetables – Heavy-feeding vegetables will need a nutritional supplement, e.g. tomato plants benefit from a low-nitrogen fertilizer when fruit starts to develop.

Harvest: Harvest mature warm season vegetables. Not sure if it’s ready to harvest? This link will help.  http://cagardenweb.ucanr.edu/Vegetables/

Plan: Order seeds for cool season vegetables.

Plant: Soil temperature is no longer a concern, but air temperature is. Continue to check the vegetable planting guide for your region.

Protect: Cover crops with shade cover to protect from hot mid-day sun; cover fruit trees and grapes with netting to exclude birds and other vertebrate pests.

Prune: Prune apricot and cherry trees in July/August. Other fruit trees may be pruned as soon as they are done producing, especially if managing height. If growing caneberries, cut two-year-old canes (floricanes) to the ground right after harvest. Remove suckers from all fruit trees.

Soil: Before planting any vegetable crops, add a 1” layer of compost or high quality organic material to the bed, work the amendments into the top 4” of soil. Water the bed evenly without over wetting; let the bed rest. At the time of planting, add organic fertilizer to the planting hole depending on the feeding needs of your vegetables (light, medium or heavy). Lightly work the fertilizer into the planting hole.

Train: Stake or cage large plants as needed to keep them upright.


Feed plants if needed: Determine the nutritional needs (N-P-K and pH) of landscape plants.

  • Flowering plants – Feed roses and other flowering plants to keep them blooming. (June)
  • Acid-loving plants – Feed azaleas, camellias, gardenias, rhododendrons and other plants adapted to acidic soil using an acid fertilizer.
  • Containers – Feed cymbidium orchids (every week to two weeks), other container plants.

Maintenance: Treat ponds with mosquito repellent. Raise the cutting height of your lawnmower 1 to 1.5” to help grass survive drought and heat (encourages deep roots and reduces water demand). Leave clippings on the ground for nutrients and as a mulch layer.

Plan: Order spring-blooming bulbs for best selection. (Aug)

Plant: Sow seeds of fall-blooming annual flowers directly in the ground; keep bed moist until seedlings emerge.

Propagate: If not done in spring, on a cool day dig up and divide overcrowded spring-blooming perennial bulbs (daffodils, daylilies, iris and tulips) and trim dead portions. Store in a cool, dry place for replanting in fall. Start seeds of cool season annuals, such as calendula, stock, etc. (August)

Protect: To reduce fire hazard, keep wild grasses and weeds mowed, leaving a 30-foot swath (where possible) around your property; trim dead growth from shrubs and trees, and prune any branches that overhang the eaves. Remove leaves and debris from the roof.

Prune: Promote another bloom cycle of perennials and annuals by lightly pruning back spent stems or shearing old growth. Lightly prune single blooming rose bushes once bloom period ends. Remove suckers (weak shoots) from the base of tree trunks or roots. Do not compost diseased material.

Train: Stake tall plants such as gladiolas, lilies & vines (June).

Integrated Pest Management for Summer

Monitor for Pests

General Pests to watch for:

  • Ants, aphids, borers, carpenter bees, carpenterworm, mosquitoes, spider mites, yellowjackets (June-Aug); scale insects (June)

Specific Pests to watch for:

  • American plum borer – Check for frass and gum on lower branch crotches and graft unions of young trees such as almond, mountain ash, olive, sycamore, and stone fruit (June-July).
  • Cherry spotted wing drosophila – Inspect cherry, raspberry, blackberry, blueberry, and strawberry crops (June).
  • Clearwing moths – Look for signs of boring in ash, birch, pine, poplar, and willow; less often in oak, sycamore, and stone fruits (June-July).
  • Green fruit beetle – Check fig and stone fruits (July).
  • Leaffooted bug – Check fruits and nuts such as almonds, pistachios, and pomegranates (June-Aug).
  • Redhumped caterpillars – Check trees such as liquidambar, redbud, stone fruits, and walnut (June-Aug).

Specific Plants to inspect:

  • Apple and pear trees – Look for codling moth (June-Aug).
  • Citrus – Check for Asian citrus psyllid (when new leaves are forming), leafminer (June-Aug), and scales (June).
  • Coast redwood dieback – Check for drought-stress related pests such as bark beetles and spider mites (June-Aug).
  • Roses – Watch for hoplia beetle and thrips (June).

For further information, refer to UC IPM Pest Notes: http://www.ipm.ucanr.edu/PMG/PESTNOTES/

Monitor for Diseases

Specific Diseases to watch for:

  • Bacterial blast, blight and canker – Inspect apple, citrus and stone fruit (July-Aug).
  • Fire blight – Look for oozing and dead limbs on pome plants such as apple, crabapple, pear & pyracantha (June-July).
  • Eutypa dieback – Look for cankers, limbs or twigs wilting on apricot and cherry (Aug).
  • Powdery mildew – Inspect apple, crape myrtle, grape, rose, and stone fruits (June-Aug).

Specific Plants to inspect:

  • Coast redwood dieback – Check for drought-stress related maladies such as abiotic disorders and fungal diseases.
  • Roses – Watch for black spot (June), powdery mildew (June-Aug).

For further information, refer to the UC IPM Disease Menu: http://www.ipm.ucanr.edu/PMG/menu.disease.html

Local Weather Information

Linked data is from the California Irrigation Management Information System (CIMIS) weather stations. Visit CIMIS web site.

Contra Costa County Stations