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Spring Garden & Landscape Checklist

March / April / May

General Tasks

Compost: Turn compost and keep it as moist as a wrung-out sponge. Add garden waste, grass clippings, pruning material & leaves so long as they are not diseased. Cover compost during rainy weather to avoid the pile becoming waterlogged.

Frost:  Late frost is possible; protect sensitive plants from cold injury when frost is predicted.

Contra Costa County last frost dates:

  • West County: Feb 15
  • Central & East County: March 15

Irrigation: Adjust watering schedules monthly, according to the weather and the changing needs of your plants. Avoid over-irrigation and waterlogged soil. Check your irrigation systems for leaks and broken emitters; perform maintenance as needed.

Mulch: Apply 2-3” of mulch where existing mulch is thin or soil is bare, especially around newly planted trees and shrubs. 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. Avoid walking on wet soil. Do not work or dig soil if it is wet.

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.

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


Feed Plants:

  • Berries, citrus and deciduous fruit trees – feed once during spring with an appropriate fertilizer, follow application rate for your product.
  • Grapes – feed with an appropriate fertilizer after the vine has blossomed or when grapes are about ¼ inch across; follow application rate for your product.
  • Acid-loving fruits – use an acid fertilizer for blueberries, cane berries, raspberries and strawberries; follow application rate for your product.

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

Plan: Develop a garden layout and timetable for cool and warm season crops, taking plant rotation into consideration.

Plant: Check the vegetable planting guide for your region.

Protect: If a frost is predicted, water citrus, avocado and other frost-sensitive plants; keep the root zone moist but not soggy. Through March, some trees may still need to be covered. If temperatures fall below 50° F, cover outdoor seedlings. In May, fruit trees and grapes can be covered with netting to exclude birds.

Prune: Thin fruit tree blossoms and developing fruit as needed.

Soil: Prepare your garden plot three weeks before planting. Weed your plot and turn (dig) in any cover crops. Loosen the soil 10-12” deep, breaking up large clods of soil. 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.


Feed plants if needed: Determine the nutritional needs (N-P-K and pH) of landscape plants. Determine the timing for repeated application of nutrients and establish a schedule. Follow the application rate for your product.

Maintenance: Eliminate standing water, e.g. in gutters, drain pipes & flowerpots, to deter mosquitoes. Clean winter debris from ponds, fountains and bird baths. Aerate and fertilize lawn areas (early May); re-seed bald patches; start mowing warm-season turf. Replace any undesirable plants in containers and replenish soil, mixing in compost. Inspect for root rot (favored by excessive water and poor drainage).

Plant: Perennials, drought-tolerant shrubs. Plant summer-blooming bulbs (callas, cannas, dahlias, gladiolas, etc.) and summer-blooming annual flowers. Frost-tender plants (bougainvillea, hibiscus) can be planted after the last frost date for your area.

Contra Costa County last frost dates:

  • West County:  Feb 15
  • Central & East County:  March 15.

Propagate: Direct sow summer and fall annuals (cosmos, marigold, nasturtiums, sunflowers, petunia, and zinnias) when soil temperatures reach 70° F. For an early start use a heat mat & grow light to germinate seeds 6-8 weeks before setting out. Harden off plants before transplanting. Sunflowers and nasturtiums do not transplant well. Divide or transplant hardy perennials (aster, chrysanthemum, hosta). Divide spring bulbs (daffodils, Pacific Coast iris, tulips).

Protect: If a frost is predicted, water your plants, keeping the root zone moist but not soggy. Cover frost-tender species as appropriate (bougainvillea, hibiscus & succulents).

Prune: Prune dead, diseased, and distorted twigs, stems and branches from winter-flowering shrubs (azaleas, camellias, rhododendrons). Clean up fallen leaves and blossoms from the area below and around your plants. Do not compost diseased material.

Integrated Pest Management for Spring

Monitor for Pests

General Pests to watch for:

  • Ants, aphids, borers, carpenter bees, mosquitoes, slugs, snails, yellowjackets (March - May); scale (April - May); spider mites (May)

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 (April - May).
  • Cherry spotted wing drosophila – Check cherry, raspberry, blackberry, blueberry, and strawberry crops (April - May).
  • Clearwing moths – Look for signs of boring in ash, birch, pine, poplar, and willow; less often in oak, sycamore, and stone fruits (April - May).
  • Codling moth – Check apple and pear trees (March - May).
  • Scab – Check apple, crabapple, and pear trees (March - April).

Specific Plants to inspect:

  • Citrus – Look for Asian citrus psyllid (when new leaves are forming); caterpillars and scales (March-May); mites and thrips (April); leafminer (May).
  • Olives – Act to suppress psyllid (March) and fruit fly (April - May); ash borer, psyllid and scales (April - May).
  • Roses – Watch for aphids (March - April); hoplia beetle and thrips (March – May).
  • Stone fruits – Watch for aphids, borers, caterpillars, and scale insects (March - May).

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

Monitor for Diseases

Specific Diseases to watch for:

  • Anthracnose (leaf blight) – Check ash and sycamore (March-May).
  • Fire blight - Look for oozing & dead limbs on pome plants such as apple, crabapple, pear & pyracantha (March - May).
  • Peach leaf curl – Check peach and nectarine trees (March - April).
  • Petal blight – Check azaleas, rhododendron and camellia (March).
  • Powdery mildew – Inspect apple, crape myrtle, grape, rose, and stone fruits (March - May).

Specific Plants to inspect:

  • Roses – Check for botrytis blight, downy mildew and rust (March - April); black spot, powdery mildew (March - May).
  • Stone fruits – Monitor for disease such as brown rot and powdery mildew (March - May).

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