Washington planting calendar

When to plant swiss chard in Washington — sow, transplant & harvest dates

Washington is mostly USDA zone 8a (range 4a-9a). Dates below are derived from swiss chard's frost tolerance and Washington's frost window — not generic national averages.

Swiss Chard planting timetable for Washington

Stage	When in Washington	Anchor
Start seeds indoors	mid-March (March 18)	4 weeks before the last frost (mid-April (Puget Sound))
Transplant outside	early April (April 8)	7 days before the last frost (mid-April (Puget Sound))
First harvest (estimate)	early June (June 2)	~55 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Washington's climate shifts the swiss chard dates

Washington's last spring frost averages mid-April (Puget Sound) and first fall frost early November (Puget Sound), which sets the whole planting clock. Washington is split by the Cascades into a mild, wet, long-season west and a colder, drier east. The Puget Sound lowland is the mildest belt. Sow early — swiss chard bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Swiss chard is notably more versatile than spinach — it tolerates both light frost (surviving to about -4 °C) and summer heat up to 32 °C, making it a near-year-round crop in Zones 7–10. Direct-sow or transplant 1 week before the last spring frost; chard seed is actually a multi-germ cluster, so thin to final spacing after germination to prevent overcrowding. Unlike spinach, it does not readily bolt in summer, so a single sowing can be harvested by cutting outer leaves repeatedly for 3–4 months.

Frost-risk note

Don't plant before mid-April (Puget Sound) — a hard freeze can still set young plants back. In the Cascades and northeast highlands (zone 4a) the safe date runs a week or two later.

Regional variation within Washington

the Cascades and northeast highlands (zone 4a) runs roughly 1-2 weeks behind the state average; the Puget Sound lowland around Seattle (zone 9a) can plant 1-2 weeks earlier.

Seattle — USDA zone 9a
Spokane — USDA zone 7a
Tacoma — USDA zone 8b
Vancouver — USDA zone 8b
Yakima — USDA zone 7a

What else to plant in Washington around then

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun to partial shade.
Soil temperature for germination: 10-29 °C (50-85 °F).
Spacing: 9-12 inches (23-30 cm) between plants.
Days to harvest: ~55 days from planting out.

Frequently asked questions

When is the best time to plant swiss chard in Washington?

In Washington (mostly USDA zone 8a), sow swiss chard indoors around mid-March, transplant outdoors early April (before the last frost, mid-April), and harvest from early June. Swiss Chard are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

What USDA zone is Washington?

Most of Washington sits in USDA hardiness zone 8a, with the state spanning roughly 4a-9a from the Cascades and northeast highlands (zone 4a) to the Puget Sound lowland around Seattle (zone 9a). The last spring frost averages mid-April (Puget Sound) and the first fall frost early November (Puget Sound).

Can you grow swiss chard in Washington?

Yes. Washington's dominant zone 8a supports swiss chard — the key is timing. Swiss Chard are half-hardy — young plants shrug off a light frost but not a hard freeze, so sowing can start a couple of weeks before the last spring frost.

Does the planting date change across Washington?

the Cascades and northeast highlands (zone 4a) runs roughly 1-2 weeks behind the state average; the Puget Sound lowland around Seattle (zone 9a) can plant 1-2 weeks earlier.

What else can I plant in Washington around the same time?

The same early window suits peas, lettuce, spinach, and onion sets.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.