Marin Master Gardeners
University of California
Marin Master Gardeners

Gardener's checklist for spring

What to do in your garden in the spring

APRIL

  • Troubleshoot your irrigation system for missing or clogged emitters and broken spray heads.
  • Fertilize spring bulbs after bloom. Remove dead flowers but not the leaves until they wither.
  • Check often for aphids on tender new plant growth. Remove infestations with a hard spray of water or insecticidal soap.
  • Handpick snails and slugs after dark or apply a pet-friendly bait.
  • Be diligent about pulling weeds before they set seed.
  • Mulch around new plants to suppress weeds and retain moisture. Renew mulch around existing plantings. Keep mulch clear of stems and trunks.
  • Weather permitting, move frost-tender seedlings and plants outdoors. Harden off transplants before planting by gradually exposing them to outdoor conditions.
  • Sow seeds of summer and fall-blooming annual flowers directly in the ground. Cosmos, bachelor buttons, sunflowers, nasturtiums and zinnias are easy to grow from seed. Keep the seed bed moist.
  • Plant summer bulbs, corms and tubers, such as callas, cannas, dahlias, gladiolus and tuberous begonias.
  • Sow seeds of beets, carrots, lettuce and Swiss chard. Plant potato tubers.
  • Thin raspberry canes.
  • Thin developing fruit such as apples when they reach dime size.
  • Feed lawn areas with a slow-release fertilizer.
  • Fertilize citrus.
  • Apply chelated iron to azaleas, camellias and gardenias if leaves are yellowing between the veins.
  • Renew container plants by adding a slow-release fertilizer or repotting in fresh soil.
  • Clean winter debris from ponds, fountains and bird baths.

MAY

  • Monitor and control snails, slugs and aphids.
  • Prune spring-flowering shrubs are they have finished flowering.
  • Pinch back chrysanthemums and annual flowering plants to encourage branching and compact growth.
  • Cut off spent flowers for continued bloom.
  • Prune azaleas, camellias and rhododendrons after they have finished blooming. Feed with a balanced fertilizer formulated for acid-loving plants monthly during the spring and summer.
  • Prune roses to open the plant to good air circulation. Pick up diseased leaves.
  • Continue to plant seeds of summer and fall-blooming annual flowers or buy cell packs at nurseries.
  • Sow seeds of beans, beets, carrots, corn (early varieties), cucumbers, lettuce, melons, pumpkins, Swiss chard and summer and winter squash.
  • Transplant starts of eggplants, peppers and tomatoes.
  • Plant an herb garden in containers or in a bed near your kitchen. Keep mint in its own pot to control its rampant spread.
  • Fertilize citrus.
  • Continue to thin developing fruit.
  • Repot cymbidiums if they have outgrown their containers or if the planting medium has broken down.
  • Cut roses to bring indoors. As you cut, plunge the stems immediately into a bucket of water.

JUNE

  • Check soil moisture and adjust the watering schedule on your irrigation controller accordingly. Water early in the day. Watch container plants, which may need daily watering.
  • Control powdery mildew, a fungus that likes dry summer conditions. Spray susceptible plants with a horticultural oil or biological fungicide.
  • Cut off spent flowers for continued bloom.
  • Promote another bloom cycle of early-blooming perennials like Shasta daisies (Leucanthemum) and catmint (Nepeta) by cutting back spent stems or shearing old growth.
  • Fertilize roses and other summer-blooming plants. Use little or no fertilizer on herbs.
  • Sow seeds of basil, beans, beets, carrots, corn (early varieties), cucumbers, lettuce, summer and winter squash.
  • Transplant starts of broccoli, Brussels sprouts, eggplant, peppers and tomatoes.
  • Make compost tea for a mild liquid fertilizer.
  • Stake tall plants such as dahlias, gladiolus and lilies as needed.
  • Provide support for the vining stems of indeterminate tomato plants. Feed with a low-nitrogen fertilizer when fruit starts to develop. Do not overwater.
  • Protect fruit crops from birds with plastic bird netting or fabric row covers.
  • Continue to thin fruit.
  • Use pot feet or boards to elevate containers sitting on hot pavement.
  • Clear dry brush and grasses to create a 30-foot fire-safe space around your home.
  • Harvest blooming lavender to dry for indoor use.

Contributors:
Faith Brown, Marie Narlock, UCCE Placer County Master Gardeners

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

Webmaster Email: banielsen@ucanr.edu