Washington · zones 6b–9a
When to plant spinach in Washington.
Sow between Feb 21 to Apr 4 in a typical year, keyed to Washington's median last frost around Apr 14. A second, fall sowing fits Aug 4 to Sep 22. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Spinach dates for a typical Washington season.
Direct sow
Feb 21 to Apr 4
Keyed to the ~Apr 14 last frost. Sow 0.5" deep, 3" apart.
Fall round
Aug 4 to Sep 22
Counted back from the ~Oct 18 first frost.
Harvest
~42 days later
~0.25 lb per plant over ~1 weeks.
Washington spans more than one climate: Zone 8 is the most common zone, but the state runs 6b to 9a. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
Washington growing notes
Spinach treats a Puget Sound winter as an extra growing season.
Cool and damp is the crop's favorite weather, not a compromise
Spinach bolts fast in heat and stalls in genuinely cold, frozen ground, which makes Puget Sound's mild, overcast climate close to ideal rather than a limitation the way it is for a heat-loving crop like tomatoes or corn. West-side winters rarely freeze the ground hard enough to stop the plant outright, and a fall-sown bed under a simple row cover can often be picked through much of the winter months rather than needing to finish before the season's first hard freeze.
That mild-winter advantage is a big part of why Washington's overall season supports around 21 spinach sowings, spaced roughly every couple of weeks from late winter through fall, a number a colder inland state could not come close to matching with the same crop. A west-side gardener who keeps a spinach bed going nearly year-round is leaning on exactly that marine-climate mildness rather than doing anything unusual with technique.
East of the mountains, the same crop runs on a much tighter clock
Columbia Basin gardens see the opposite challenge: spinach bolts within days once early summer heat sets in, since the plant reads long, warm days as a signal to flower rather than keep growing leaves, and a Basin garden can lose an entire planting to bolting inside a single hot week if the timing runs late. Spring and fall are the two windows that matter there, with the entire summer effectively skipped rather than fought.
Soil needs to hold at least 40 to 45 degrees at 2 inches deep before spinach seed sprouts reliably, checked in the morning rather than the afternoon, since a midday sun-warmed number overstates what the ground held through the night; east-side gardeners get that reading sooner in spring than west-side gardens do, thanks to less cloud cover slowing soil warm-up, even though the region's summer window closes faster once heat arrives.
Leaf miners tunnel where a spray cannot reach
Leaf miners spend their larval stage sealed inside a leaf, tunneling a path between the upper and lower surfaces that shows up from outside as a pale, meandering trail; no surface spray can reach an insect that is physically walled inside the leaf it is eating. Once that trail appears, pulling and destroying the affected leaf right away is the only real fix, since it stops that particular larva before it matures into a fly that lays a fresh round of eggs on the next healthy leaf over.
A floating row cover put down at sowing, before the adult fly has a chance to lay eggs on the leaves in the first place, is the more reliable west-side and east-side defense either way, since it denies the fly access rather than reacting after damage has already started; aphids and flea beetles round out the pest list and both rinse or brush off a young planting without much trouble if caught early.
In Washington: watch for
The pests that find spinach here.
A middle-length season, about 187 frost-free days, means spinach overlaps leaf miners for a stretch each summer. Check plants every week or two and treat early.
Winding pale tunnels or blotches inside the leaves.
Organic fix: Pick and destroy mined leaves; cover the row.
Cercospora leaf spot
Round spots with gray centers and a red-purple rim, oldest leaves worst.
Organic fix: Space wider so leaves dry fast, clear old debris, and pull pigweed and lambsquarters nearby.
Your season math: Washington gives spinach about 187 frost-free days, and it needs roughly 42 days to a first harvest. That fits about 21 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting spinach in Washington: questions
When should I plant spinach in Washington?+
In a typical Washington year, sow spinach between Feb 21 to Apr 4, keyed to the state's median last frost around Apr 14. There's also a fall window: Aug 4 to Sep 22. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Washington?+
Washington spans zones 6b–9a, mostly zone 8. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many spinach plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.