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Hands cupping a young collard plant with broad, veined leaves
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When to plant collards in Portland, OR

Start collards from seed indoors Feb 1–15, then plant the young plants in the garden in Portland Mar 15 – Apr 26. For a fall harvest, plant again Aug 6–20.

Easy Plant young plants (starts)

Difficulty
Easy
Sun
Full sun to part shade
Spacing
18 to 24 inches apart
Planting depth
Plant starts at the depth they grew in the pot
Frost
Handles light frost
First harvest
About 60 days after planting

Why these dates

Portland's typical last spring frost is March 13. In the west-side valleys, the soil is usually ready for collards 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.

How to grow collards in Portland

  1. Start seeds indoors Feb 1–15 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, 18 to 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. Plant again Aug 6–20 for a fall harvest.
  6. Harvest: Pick the lower leaves when they're about the size of your hand, and let the top keep growing. Leaves picked after a frost taste sweetest.

Key numbers

Growing notes

What makes the difference in Northwest gardens, in plain language.

Why collards suit Northwest winters

Collards are a loose-leaf member of the cabbage family, very close to kale. They're tougher than most of their cousins: established plants usually ride out freezes into the low teens, and cold weather turns some of the starch in the leaves to sugar, which is why winter collards taste milder and sweeter than summer ones.

West of the Cascades, a planting set out in midsummer gives leaves from fall right through to spring. East of the Cascades, hard winters can kill them, but fall harvests are still excellent.

Soil, feeding and picking

Like all leafy cabbage-family crops, collards want rich soil with plenty of nitrogen and a pH of about 6.0 to 7.5. Mix in compost before planting and side-dress with a balanced fertilizer a month later. Keep the soil evenly moist; stressed plants get tough, bitter leaves.

Pick from the bottom up, taking two or three leaves per plant at a time and leaving the growing tip alone. A well-fed plant keeps making new leaves for months.

Keeping pests off

The white cabbage butterfly lays eggs on the leaves, and the green caterpillars that hatch chew big holes. Aphids cluster under leaves in late summer. Insect netting or row cover laid over hoops from planting day is the simplest fix. Hand-pick any caterpillars you find, and knock aphids off with a strong spray of water.

Don't grow collards in the same spot as kale, cabbage or broccoli two years running. That breaks the cycle of clubroot and other soil diseases the family shares.

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 collards in Portland?

The spring planting window runs through April 26. If you miss it, plant again for fall from August 6 to August 20.

When should I start collards from seed indoors in Portland?

February 1 to February 15, which is 6 to 4 weeks before the March 15 planting date. Or buy young plants at a garden center instead.

What's the difference between collards and kale?

They're the same species with different leaves. Collards have broad, flat, smooth leaves; most kales are curly or crinkled. Collards are a bit more heat-tolerant and slightly milder.

When do collards taste best?

After a few frosts. Cold makes the plant store sugar in its leaves, so fall and winter collards are noticeably sweeter.

Can I grow collards in summer?

Yes, they handle heat better than most cabbage-family greens. In hot eastern valleys, give them afternoon shade and steady water.

Also plant in Portland around the same time

Planting dates for collards in nearby areas

Full planting calendar for Portland · Collards in every city