When to plant rhubarb in Sunnyside, Grandview and Prosser, WA

Plant rhubarb crowns in Sunnyside, Grandview and Prosser Mar 20 – May 1.

Easy Plant dormant crowns

Difficulty: Easy
Sun: Full sun to part shade
Spacing: 3 to 4 feet apart
Planting depth: Crown buds 1 to 2 inches below the surface
Frost: Hardy perennial; comes back every year
First harvest: Light picking in year two; full harvests from year three

Why these dates

Sunnyside, Grandview and Prosser's typical last spring frost is May 1. As a hardy perennial, this crop doesn't need to wait for that date. In the Columbia Basin and low eastern valleys, though, the soil usually isn't ready to work until about March 20.

Columbia Basin and low eastern valleys. Hot, dry summers and quick spring warm-up. Warm crops go in earlier than west of the Cascades, and irrigation matters more than rain.

How to grow rhubarb in Sunnyside, Grandview and Prosser

Pick a sunny spot with soil that drains well, and mix in an inch or two of compost.
Plant rhubarb crowns Mar 20 – May 1, 3 to 4 feet apart. Crown buds 1 to 2 inches below the surface.
Mulch with compost each spring, and cut off flower stalks as soon as they appear.
Harvest: Pull (don't cut) stalks when they're 10 to 15 inches long. Take no more than a third at once, and stop in early summer. Never eat the leaves.

Key numbers

6.0–6.8Soil pH
10–15 inches longPull stalks at
Every 5–10 yearsDivide
Crown rot in wet soilBiggest risk

Growing notes

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

Soil and feeding

Rhubarb is a hungry perennial that grows huge leaves every spring, so it rewards rich soil. Dig plenty of compost or aged manure into a wide area before planting, and spread a couple of inches of compost around the plant each spring, keeping it off the crown itself. Good drainage is essential: crowns rot in soggy winter soil, which is why west-side gardeners often plant on a low mound.

Rhubarb needs a cold winter to rest, which every part of the Northwest provides.

Harvest without weakening the plant

Pull stalks with a twist instead of cutting them, which leaves no stub to rot. Take no more than a third of the stalks at a time and stop in early summer, so the leaves that remain can rebuild the crown for next year. Thin, spindly stalks are a sign to stop sooner.

The leaves contain high levels of oxalic acid and are poisonous to eat, so cut them off and use only the stalks. Leaves are fine to put in the compost pile.

Care over the years

Cut flower stalks off at the base as soon as they appear; seed-making takes energy away from new leaves. Older plants flower more, and so do stressed ones.

After five to ten years, clumps get crowded and stalks get thinner. In early spring, just as buds swell, dig the crown and split it with a sharp spade into pieces that each have at least one or two buds and a good chunk of root. Replant them in fresh, enriched soil.

Common questions

When is the last frost in Sunnyside, Grandview and Prosser, WA?

Typically May 1. In 9 years out of 10, frost is over by May 18. These are 1991–2020 NOAA climate normals for Sunnyside.

Is it too late to plant rhubarb in Sunnyside, Grandview and Prosser?

The spring planting window runs through May 1. Potted plants can still go in later if you water them faithfully through their first summer.

How long until I can pick rhubarb?

Light picking in year two; full harvests from year three. Pull (don't cut) stalks when they're 10 to 15 inches long. Take no more than a third at once, and stop in early summer. Never eat the leaves.

Why is my rhubarb flowering?

Mature plants flower naturally, and stress from heat, drought or poor soil makes it more likely. Cut the flower stalk off at the base right away. If a plant flowers heavily every year, it may be time to divide it.

Why are my rhubarb stalks green instead of red?

Color depends on the variety, not ripeness. Victoria is mostly green with red at the base, while Canada Red and Crimson Red are redder. Green stalks taste just as good, though they make paler pies and jam.

Can I put rhubarb leaves in my compost?

Yes. The oxalic acid that makes the leaves poisonous to eat breaks down during composting and doesn't harm the pile or your soil. Just don't feed them to people or animals.

Also plant in Sunnyside, Grandview and Prosser around the same time

Planting dates for rhubarb in nearby areas

Yakima, WA Mar 27 – May 8
Tri-Cities (Pasco, Kennewick, Richland), WA Mar 20 – May 1
Walla Walla, WA Mar 20 – May 1
Moses Lake, WA Mar 20 – May 1
Ellensburg, WA Apr 1 – May 13
Ephrata and Quincy, WA Mar 20 – May 1

Full planting calendar for Sunnyside, Grandview and Prosser · Rhubarb in every city