Rainline Garden

When to plant broccoli in Seattle and Tacoma, WA

Start broccoli from seed indoors Jan 25 – Feb 8, then plant the young plants in the garden in Seattle and Tacoma Mar 15 – Apr 19. For a fall harvest, plant again Jul 23 – Aug 6.

Moderate Plant young plants (starts)

Why these dates

Seattle and Tacoma's typical last spring frost is March 2. In the west-side valleys, the soil is usually ready for broccoli around March 15.

West-side valleys. The Willamette Valley, Puget Sound and southern Oregon valleys. Long frost-free seasons, but soil stays cold and wet into May, so warm crops wait for warm soil, not just the last frost.

Difficulty
Moderate
Sun
Full sun
Spacing
18 inches apart
Planting depth
Plant starts at the depth they grew in the pot
Frost
Handles light frost
First harvest
About 70 days after planting

Step by step

  1. Start seeds indoors Jan 25 – Feb 8 in trays or small pots under a grow light or in your sunniest window. Or skip this step and buy young plants (starts) at a garden center.
  2. Harden off the young plants: about a week before planting, set them outside for a few hours a day, a little longer each day.
  3. Plant them in the garden Mar 15 – Apr 19, 18 inches apart. Plant starts at the depth they grew in the pot.
  4. Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
  5. Plant again Jul 23 – Aug 6 for a fall harvest.
  6. Harvest: Cut the main head while the buds are tight and dark green. Side shoots follow for weeks.

Varieties that do well here

  • Packman
  • Green Magic
  • Purple Sprouting (overwinters west of the Cascades)

Watch out for

Cabbage worms and aphids. Cover young plants with insect netting.

Harvest the main head while buds are tight; side shoots follow for weeks.

Common questions

When is the last frost in Seattle and Tacoma, WA?

Typically March 2. In 9 years out of 10, frost is over by March 23. These are 1991–2020 NOAA climate normals for Seattle-Tacoma International Airport.

Is it too late to plant broccoli in Seattle and Tacoma?

The spring planting window runs through April 19. If you miss it, plant again for fall from July 23 to August 6.

When should I start broccoli from seed indoors in Seattle and Tacoma?

January 25 to February 8, which is 7 to 5 weeks before the March 15 planting date. Or buy young plants at a garden center instead.

Also plant in Seattle and Tacoma around the same time

Planting dates for broccoli in nearby areas

Full planting calendar for Seattle and Tacoma · Broccoli in every city