Rainline Garden

When to plant Brussels sprouts in Portland, OR

Start Brussels sprouts from seed indoors Jan 18 – Feb 1, then plant the young plants in the garden in Portland Mar 15 – Apr 26.

Moderate Plant young plants (starts)

Why these dates

Portland's typical last spring frost is March 13. In the west-side valleys, the soil is usually ready for Brussels sprouts 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
24 inches apart
Planting depth
Plant starts at the depth they grew in the pot
Frost
Handles light frost
First harvest
About 100 days after planting

Step by step

  1. Start seeds indoors Jan 18 – Feb 1 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 26, 24 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. Harvest: Pick sprouts from the bottom of the stalk up once they're firm and about an inch across. Frost improves the flavor.

Varieties that do well here

  • Long Island Improved
  • Diablo
  • Churchill

Watch out for

Aphids cluster on the sprouts in late summer. Knock them off with a strong spray of water every few days.

A long-season crop picked in fall and winter, when frost sweetens the sprouts. West of the Cascades, plants keep producing well into winter.

Common questions

When is the last frost in Portland, OR?

Typically March 13. In 9 years out of 10, frost is over by April 1. These are 1991–2020 NOAA climate normals for Portland International Airport.

Is it too late to plant Brussels sprouts in Portland?

The spring planting window runs through April 26. Later plantings tend to struggle in summer heat.

When should I start Brussels sprouts from seed indoors in Portland?

January 18 to February 1, which is 8 to 6 weeks before the March 15 planting date. Or buy young plants at a garden center instead.

Also plant in Portland around the same time

Planting dates for Brussels sprouts in nearby areas

Full planting calendar for Portland · Brussels sprouts in every city