Rainline Garden

When to plant sunflowers in Tri-Cities (Pasco, Kennewick, Richland), WA

Plant sunflowers from seed, directly in the garden in Tri-Cities (Pasco, Kennewick, Richland), May 4 – Jun 15.

Easy Plant seeds in the ground

Why these dates

Tri-Cities (Pasco, Kennewick, Richland)'s typical last spring frost is April 27. Frost kills sunflowers, so planting starts once frost risk drops, around May 4. Keep row cover or a frost blanket handy for the first couple of weeks, since a late frost is still possible.

Columbia Basin and low eastern valleys. Hot, dry summers and quick spring warm-up. Warm crops go in earlier than west of the Cascades, and irrigation matters more than rain.

Difficulty
Easy
Sun
Full sun
Spacing
6 inches (small types) to 24 inches (giants) apart
Planting depth
1 inch deep
Frost
Killed by frost
Flowers
Blooms about 60 to 90 days after sowing

Step by step

  1. Prepare the bed: loosen the soil and mix in an inch or two of compost.
  2. Plant seeds May 4 – Jun 15, 1 inch deep, 6 inches (small types) to 24 inches (giants) apart.
  3. Keep the soil evenly moist until sprouts appear, which can take one to three weeks in cool soil.
  4. Harvest: Cut flowers when the petals are just opening. For seeds, let heads dry on the plant until the back turns brown, and cover them from birds.

Varieties that do well here

  • Mammoth Grey Stripe (giant)
  • ProCut (for cutting)
  • Teddy Bear (dwarf)

Watch out for

Birds and slugs eat seedlings. Cover the seedbed until plants are a few inches tall.

Sow them where they'll grow; they dislike transplanting. Tall varieties need a spot out of the wind.

Common questions

When is the last frost in Tri-Cities (Pasco, Kennewick, Richland), WA?

Typically April 27. In 9 years out of 10, frost is over by May 10. These are 1991–2020 NOAA climate normals for Pasco Tri-Cities Airport.

Is it too late to plant sunflowers in Tri-Cities (Pasco, Kennewick, Richland)?

The spring planting window runs through June 15. Later plantings may not have time to bloom well before the first fall frost, which usually arrives around October 11.

When do sunflowers bloom?

Blooms about 60 to 90 days after sowing. Cut flowers when the petals are just opening. For seeds, let heads dry on the plant until the back turns brown, and cover them from birds.

Also plant in Tri-Cities (Pasco, Kennewick, Richland) around the same time

Planting dates for sunflowers in nearby areas

Full planting calendar for Tri-Cities (Pasco, Kennewick, Richland) · Sunflowers in every city