Rainline Garden

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

Plant sweet peas from seed, directly in the garden in Tri-Cities (Pasco, Kennewick, Richland), Mar 20 – Apr 24.

Moderate Plant seeds in the ground

Why these dates

Tri-Cities (Pasco, Kennewick, Richland)'s typical last spring frost is April 27. As a cool-season crop that handles light frost, this crop doesn't need to wait for that date. In the Columbia Basin and low eastern valleys, though, the soil usually isn't ready to work until about March 20.

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
Moderate
Sun
Full sun
Spacing
4 to 6 inches apart along a trellis
Planting depth
1 inch deep (soak seeds overnight first)
Frost
Handles light frost
Flowers
Blooms in early summer

Step by step

  1. Prepare the bed: loosen the soil and mix in an inch or two of compost.
  2. Plant seeds Mar 20 – Apr 24, 1 inch deep (soak seeds overnight first), 4 to 6 inches apart along a trellis.
  3. Keep the soil evenly moist until sprouts appear, which can take one to three weeks in cool soil.
  4. Harvest: Cut stems every couple of days; the more you pick, the more they bloom. Plants stop flowering once pods form.

Varieties that do well here

  • Cupani (very fragrant)
  • Spencer mix
  • Royal Family (more heat-tolerant)

Watch out for

Aphids and powdery mildew late in the season. Sow early so plants peak before summer heat.

A classic cut flower that loves cool Northwest springs. Sow early, give them a trellis and pick often. The seeds are toxic, so these are for flowers only.

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 sweet peas in Tri-Cities (Pasco, Kennewick, Richland)?

The spring planting window runs through April 24. Later plantings tend to struggle in summer heat.

When do sweet peas bloom?

Blooms in early summer. Cut stems every couple of days; the more you pick, the more they bloom. Plants stop flowering once pods form.

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

Planting dates for sweet peas in nearby areas

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