When to plant cauliflower in Oak Harbor and Whidbey Island, WA

Start cauliflower from seed indoors Jan 25 – Feb 8, then plant the young plants in the garden in Oak Harbor and Whidbey Island Mar 15 – Apr 12. For a fall harvest, plant again Jul 16–30.

Tricky here Plant young plants (starts)

Difficulty: Tricky here
Sun: Full sun
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 75 days after planting

Why these dates

Oak Harbor and Whidbey Island's typical last spring frost is March 13. In the west-side valleys, the soil is usually ready for cauliflower 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 cauliflower in Oak Harbor and Whidbey Island

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.
Harden off the young plants: about a week before planting, set them outside for a few hours a day, a little longer each day.
Plant them in the garden Mar 15 – Apr 12, 18 to 24 inches apart. Plant starts at the depth they grew in the pot.
Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
Plant again Jul 16–30 for a fall harvest.
Harvest: Cut the head while it's firm and tight, before the curds start to separate. Tie the outer leaves over young heads to keep them white.

Key numbers

Soil 50°F or warmerPlant out
6.0–7.0Soil pH
1–1.5 inches a week, evenlyWater
Button headsBiggest risk

Growing notes

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

Soil and feeding

Cauliflower needs rich, moisture-holding soil with plenty of compost and a pH of about 6.0 to 7.0. It is sensitive to a shortage of boron, a trace nutrient, which can cause hollow stems and brown heads; a good compost or a complete vegetable fertilizer usually covers it. Side-dress with nitrogen about a month after planting. Above all, keep growth steady. Cauliflower has little tolerance for a check in growth, so water evenly and mulch once the soil is warm.

Why cauliflower makes tiny heads

If young plants are stressed by cold, drought, crowding or being root-bound, they can form a small "button" head early instead of a full one. That's why the guide warns against rushing spring planting. Set out young, healthy starts after the worst cold has passed, and don't let them dry out. In the Northwest, fall crops planted in mid-summer are often the most reliable, because heads form in cool, even weather. East of the Cascades, hot early summer weather can also cause loose, ricey heads, which is another reason fall crops shine there.

Blanching, harvest and storage

Sunlight turns white heads yellowish and stronger tasting. When the head is about the size of an egg, pull the outer leaves over it and tie them loosely, or snap a few leaves over the top. Purple types like Graffiti don't need this. Check under the leaves every few days, since heads go from ready to overripe quickly. Cut while the curds are tight and smooth. Cauliflower keeps about a week in the fridge, and blanched florets freeze well.

Common questions

When is the last frost in Oak Harbor and Whidbey Island, WA?

Typically March 13. In 9 years out of 10, frost is over by April 1. These are 1991–2020 NOAA climate normals for Whidbey Island Naval Air Station.

Is it too late to plant cauliflower in Oak Harbor and Whidbey Island?

The spring planting window runs through April 12. If you miss it, plant again for fall from July 16 to July 30.

When should I start cauliflower from seed indoors in Oak Harbor and Whidbey Island?

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.

Why is my cauliflower head so small?

Stress early in life, from cold snaps, dry soil, or pot-bound transplants, makes plants form small button heads. Plant young starts, keep the soil evenly moist and feed well. Fall crops usually do better in the Northwest.

Why is my cauliflower turning yellow or purple?

Sun exposure discolors white heads. Tie the outer leaves over the head when it's small to keep it pale. The color change is harmless, though the flavor gets a bit stronger.

When should I plant fall cauliflower?

Set out starts in mid-summer so heads form in the cool weather of fall. Keep young plants well watered through late summer heat. Check the planting calendar for your area's dates.

Also plant in Oak Harbor and Whidbey Island around the same time

Planting dates for cauliflower in nearby areas

Bellingham, WA Mar 15 – Apr 12
Mount Vernon and Burlington, WA Mar 15 – Apr 12
Anacortes, WA Mar 15 – Apr 12
Friday Harbor and the San Juans, WA Mar 15 – Apr 12
Portland, OR Mar 15 – Apr 12
Gresham, OR Mar 15 – Apr 12

Full planting calendar for Oak Harbor and Whidbey Island · Cauliflower in every city