Rainline Garden My garden plan
Kohlrabi bulbs swelling above the soil in a garden row
Photo: Pexels

When to plant kohlrabi in La Grande, OR

Plant kohlrabi in the garden in La Grande Apr 15 – May 27, either as seeds or as young plants started indoors Mar 4–18. For a fall harvest, plant again Jul 30 – Aug 13.

Easy Plant seeds or young plants

Difficulty
Easy
Sun
Full sun
Spacing
Thin to 6 inches apart
Planting depth
¼ to ½ inch deep
Frost
Handles light frost
First harvest
About 55 days after planting

Why these dates

La Grande's typical last spring frost is May 6. 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 15.

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

How to grow kohlrabi in La Grande

  1. Start seeds indoors Mar 4–18 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 Apr 15 – May 27, Thin to 6 inches apart. If you plant seeds instead, sow them ¼ to ½ inch deep.
  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 30 – Aug 13 for a fall harvest.
  6. Harvest: Cut bulbs at 2 to 3 inches across. Peel off the tough skin and eat raw or cooked.

Key numbers

Growing notes

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

Soil and steady growth

Kohlrabi is in the cabbage family, and the bulb is actually a swollen stem that sits above the soil. It wants fertile soil with compost, a pH of about 6.0 to 7.5, and steady moisture. Feed lightly at planting. The key to a tender bulb is fast, uninterrupted growth: dry spells or heat make the flesh fibrous. Mulch once plants are up to keep the soil evenly moist.

Timing and why bulbs get woody

Kohlrabi is quick, about two months from seed, and prefers cool weather. Spring crops should go in early, and starts set out too early into a long cold spell may bolt instead of forming a bulb. In the Northwest, fall crops sown in midsummer are especially reliable. Bulbs turn woody when left too long or when grown in hot weather, so pick at tennis-ball size. Kossak is an exception: it's bred to grow large while staying tender, and it stores well. East of the Cascades, get spring crops in early to beat the heat.

Pests, harvest and storage

Cabbage worms chew the leaves; insect netting keeps the white butterflies from laying eggs. Root maggots and flea beetles can also show up, and the same cover helps. Cut the stem just below the bulb when it reaches 2 to 3 inches across. Remove the leaves (young ones are good cooked), peel the tough outer skin, and eat it raw or cooked. Bulbs keep several weeks in a bag in the fridge, and longer for large storage types.

Common questions

When is the last frost in La Grande, OR?

Typically May 6. In 9 years out of 10, frost is over by May 26. These are 1991–2020 NOAA climate normals for La Grande.

Is it too late to plant kohlrabi in La Grande?

The spring planting window runs through May 27. If you miss it, plant again for fall from July 30 to August 13.

When should I start kohlrabi from seed indoors in La Grande?

March 4 to March 18, which is 6 to 4 weeks before the April 15 planting date. Or buy young plants at a garden center instead.

Why is my kohlrabi woody?

It was likely left to grow too big, grown in hot weather, or short on water. Pick at about tennis-ball size and keep the soil evenly moist. Cool-season crops are the most tender.

How do you know when kohlrabi is ready?

When the bulb is 2 to 3 inches across, usually about two months after sowing. Cut it at the base. Don't wait too long, since bigger bulbs toughen quickly.

What part of kohlrabi do you eat?

Mainly the round bulb, which is a swollen stem. Peel off the tough skin and eat it raw like an apple-crisp radish or cooked. The young leaves can be cooked like kale.

Also plant in La Grande around the same time

Planting dates for kohlrabi in nearby areas

Full planting calendar for La Grande · Kohlrabi in every city