Rainline Garden

When to plant onions in Ellensburg, WA

Plant onion sets in Ellensburg Apr 1 – May 6.

Moderate Plant small onion bulbs (sets)

Why these dates

Ellensburg's typical last spring frost is April 28. As a cool-season crop that handles light frost, this crop doesn't need to wait for that date. In the Inland Northwest, though, the soil usually isn't ready to work until about April 1.

Inland Northwest. Higher, colder interior valleys. Cold springs and an earlier fall mean a shorter season; quick-maturing varieties pay off.

Difficulty
Moderate
Sun
Full sun
Spacing
4 inches apart
Planting depth
Sets 1 inch deep, tip just showing
Frost
Handles light frost
First harvest
About 110 days after planting

Step by step

  1. Prepare the bed: loosen the soil and mix in an inch or two of compost.
  2. Plant onion sets Apr 1 – May 6, 4 inches apart, sets 1 inch deep, tip just showing.
  3. Water regularly and keep the bed weeded; onions don't compete well.
  4. Harvest: When the tops flop over in late summer, pull the onions and let them dry in a shady, airy spot for two weeks.

Varieties that do well here

  • Walla Walla Sweet
  • Copra (stores well)
  • Redwing

Watch out for

Weeds outcompete onions' thin leaves. Keep the bed weeded and mulched.

Plant as soon as the soil is dry enough to work. Pick long-day varieties for the Northwest.

Common questions

When is the last frost in Ellensburg, WA?

Typically April 28. In 9 years out of 10, frost is over by May 12. These are 1991–2020 NOAA climate normals for Ellensburg Bowers Field.

Is it too late to plant onions in Ellensburg?

The spring planting window runs through May 6. Later plantings tend to struggle in summer heat.

How long until I can harvest onions?

About 110 days after planting. When the tops flop over in late summer, pull the onions and let them dry in a shady, airy spot for two weeks.

Also plant in Ellensburg around the same time

Planting dates for onions in nearby areas

Full planting calendar for Ellensburg · Onions in every city