Author: Jagdish Reddy | 10+ Years Sustainable Gardening Experience
Verification: Cross-referenced with USDA Climate Data & University Research
Status: Verified for current US regional growing conditions
Last Updated: March, 2026

QUICK ANSWER: In Western Washington (Zones 7–9), start cool-season vegetables outdoors from late February through March, and transplant warm-season crops like tomatoes and peppers after Memorial Day weekend. In Eastern Washington (Zones 5–7), wait until mid-April for cool-season outdoor sowing and late May for warm-season transplants. Your local last spring frost date is the anchor for everything — count backward from it to set all your indoor seed-starting dates.

Washington State is one of the most rewarding — and genuinely tricky — places to garden in North America. The Cascade Mountains split the state into two very different climates, and what works in Seattle won’t work in Spokane. This Washington State planting calendar covers both regions with specific planting windows for vegetables, herbs, and flowers, plus frost dates, indoor seed-starting schedules, and a full quick-reference table so planning your garden planting schedule is straightforward.

Washington Planting Calendar — Quick Reference Table

This guide combines USDA hardiness zone data, WSU Extension horticulture recommendations, and practical Pacific Northwest gardener experience. Use the table below as your at-a-glance Washington State garden calendar.  W. WA = Western Washington; E. WA = Eastern Washington.

Crop	Start Indoors	Transplant Outside	Direct Sow	Region Notes
Tomatoes	Late Feb–Mar	Late May–June	—	E. WA: mid-May OK in Yakima / Tri-Cities
Peppers	Early Feb	Early June (W.WA)	—	E. WA: late May; start 2–3 wks before tomatoes
Eggplant	Early Feb	Early June	—	Both regions; needs heat
Cucumbers	Early Apr	Mid–Late May	May (65°F soil)	E. WA: excellent producers
Summer Squash / Zucchini	Late Apr	Mid May	May after frost	Both regions
Winter Squash / Pumpkins	Early–Mid Apr	Mid–Late May	May after frost	Both regions
Beans (green / pole)	—	—	May–July	Succession sow every 3 weeks
Corn	—	—	May–June	E. WA’s hot summers ideal
Melons / Watermelon	Late Mar–Early Apr	Late May–June	—	E. WA only; use row cover
Peas	—	—	Mar–Apr (W.WA); Late Mar (E.WA)	Cool season; sow early
Lettuce / Salad Mix	Feb–Mar	Mar–Apr	Mar–Sept (W.WA)	Succession plant every 3–4 wks
Spinach	—	—	Feb–Apr; Aug–Sept	Bolts in summer heat
Kale / Chard	Feb–Mar	Mar–Apr	Mar–Aug	Overwinters in W. WA
Broccoli / Cauliflower	Mid Feb–Mar	Late Mar–Apr	—	Also: start July for fall harvest
Cabbage	Mid Feb–Mar	Late Mar–Apr	—	Both regions
Carrots	—	—	Mar–July	Needs loose soil; succession sow
Beets	—	—	Mar–July	Both regions; easy direct sow
Radishes	—	—	Mar–Sept	30-day crop; very easy succession
Onions (long-day)	Late Dec–Jan	Mar–Apr	—	Long-day varieties required for WA
Leeks	Jan–Early Feb	Mar–Apr	—	Hardy; transplant early
Garlic	—	—	Oct–Nov (fall)	Harvest following July
Potatoes (seed)	—	—	Mar–May	E. WA: major production region
Basil	Late Mar–Early Apr	Late May–June	—	Most frost-tender herb; don’t rush
Parsley	Feb–Mar	Apr–May	—	Slow germinator; start early
Cilantro	—	—	Mar–May; Aug–Sept	Cool-season; bolts in heat
Dill	—	—	Apr–June	Direct sow only
Sweet Peas	Feb–Mar	Late Feb–Mar	Feb–Mar (W.WA)	Sow very early; hate heat
Dahlias (tubers)	—	—	Plant May–June	W. WA’s signature summer flower
Zinnias	Late Apr–May	Late May–June	Late May–June	Need warmth; don’t rush in W. WA
Sunflowers	—	—	May–Early June	After soil warms to 60°F
Nasturtiums	—	—	Apr–May after frost	Very easy direct sow
Tulips / Daffodils / Alliums	—	—	Oct–Nov (fall)	Spring bloom; plant bulbs in fall

Bookmark this Washington planting calendar as your year-round reference — you’ll come back to it every season.

Garden Planner Tool

Plan your garden layout using this interactive planner. Enter your garden size to calculate plant spacing and planting timing based on this planting calendar.

This planner helps turn the planting calendar above into a practical garden layout based on your available space.

🗓 Washington Planting Calendar — Key Dates by Region Western Washington (Zones 7–9) Cool-season crops outdoors → February – March Warm-season transplants (tomatoes, peppers) → Late May Fall crops start indoors → July – August Garlic planting → October – November Eastern Washington (Zones 5–7) Cool-season crops outdoors → April Warm-season transplants → Mid–Late May Fall crops → August – September Garlic planting → October – November

Washington State USDA Zones and Frost Dates

Washington Planting Calendar: Key Frost Dates at a Glance Seattle / Puget Sound: Last frost March 1–15 · First fall frost Nov 15–30 Tacoma / Olympia: Last frost March 15–April 1 · First fall frost Nov 1–15 Bellingham: Last frost April 1–15 · First fall frost Oct 15–31 Vancouver, WA: Last frost March 15–April 1 · First fall frost Nov 1–20 Spokane: Last frost May 1–15 · First fall frost Oct 1–15 Yakima: Last frost April 15–May 1 · First fall frost Oct 15–31 Tri-Cities (Kennewick): Last frost April 1–15 · First fall frost Oct 31–Nov 15 Walla Walla: Last frost April 1–15 · First fall frost Nov 1–15 NE Mountains (Colville): Last frost May 15–June 1 · First fall frost Sept 15–30

Washington spans USDA Hardiness Zones 4 through 9. The Cascade Mountains act as a climate wall, creating two fundamentally different gardening environments on either side.

City / Region	Zone	Last Spring Frost	First Fall Frost	Growing Season
Seattle	8a–8b	March 1–15	Nov 15–30	~245 days
Olympia / Tacoma	7b–8a	March 15–April 1	Nov 1–15	~220 days
Bellingham	7b–8a	April 1–15	Oct 15–31	~195 days
Vancouver, WA	8a–8b	March 15–April 1	Nov 1–20	~225 days
Spokane	6a–6b	May 1–15	Oct 1–15	~150 days
Yakima	6b–7a	April 15–May 1	Oct 15–31	~175 days
Tri-Cities (Kennewick)	7a–7b	April 1–15	Oct 31–Nov 15	~205 days
Walla Walla	7a–7b	April 1–15	Nov 1–15	~205 days
Colville / NE Mts.	4b–5a	May 15–June 1	Sept 15–30	~115 days

These are historical averages, not guarantees. In any given year, spring arrives two to three weeks earlier or later. Always check your 10-day forecast before transplanting frost-sensitive crops like tomatoes, basil, and cucumbers.

Western vs. Eastern Washington: Key Planting Differences

Factor	Western Washington	Eastern Washington
Last spring frost	March – early April	April – May 15
First fall frost	November – December	October – early November
Growing season	~200–245 days	~115–205 days
Summer temperatures	Mild; rarely above 90°F	Hot; regularly 90–100°F+
Best cool-season crops	Kale, chard, brassicas, greens	Peas, spinach, lettuce (spring)
Best warm-season crops	Tomatoes (with effort), dahlias	Corn, peppers, melons, dry beans
Irrigation need	Low — rainfall usually sufficient	Essential — dry summers
Winter gardening	Yes — kale, chard, leeks overwinter	No — ground freezes
Tomato transplant date	Late May – early June	Mid May (warmer areas)
Garlic planting	October – December	October – November

When to Start Seeds Indoors in Washington State

Indoor seed starting is how Washington gardeners compensate for cool springs and short frost-free windows. Both sides of the Cascades benefit — the west side needs a head start on heat-loving crops; the east side’s short season makes early starts essential for squash and melons. One important note: Washington winters don’t provide enough daylight for seedlings without supplemental lighting. A basic LED or fluorescent shop light kept 2–3 inches above seedlings for 14–16 hours daily produces dramatically stronger transplants than a windowsill alone.

Western Washington Indoor Seed-Starting Schedule

Crop	Start Indoors	Weeks Before Transplant	Transplant Date
Onions (long-day)	Late Dec–Early Jan	12–14 wks	Mar–Apr
Leeks	Jan–Early Feb	10–12 wks	Mar–Apr
Celery / Celeriac	Early–Mid Feb	10–12 wks	Late Apr–May
Peppers	Early–Mid Feb	10–12 wks	Early June
Eggplant	Early–Mid Feb	10–12 wks	Early June
Tomatoes	Late Feb–Early Mar	8–10 wks	Late May–June
Broccoli / Cauliflower	Mid Feb–Mar	6–8 wks	Late Mar–Apr
Kale / Cabbage	Mid Feb–Mar	6–8 wks	Mar–Apr
Lettuce / Salad Mix	Feb–Mar	4–6 wks	Mar–Apr
Basil	Late Mar–Early Apr	6–8 wks	Late May–June
Snapdragons / Stock	Early–Mid Feb	8–10 wks	Late Mar–Apr

Eastern Washington — Key Indoor Start Dates

Count 8–10 weeks back from your local last frost date. Key crops and lead times:

• Peppers — start early–mid March; transplant late May–June
• Tomatoes — start mid–late March; transplant mid–late May
• Melons / Watermelon — start late March–early April; transplant late May–June with row cover
• Cucumbers — start early April; transplant mid–late May (or direct sow at 65°F soil)
• Broccoli / Cabbage — start early–mid March; transplant early–mid April
• Winter Squash — start early–mid April; transplant mid–late May

Monthly Planting Calendar for Washington State

Western WA dates appear first throughout. Where Eastern WA differs meaningfully, it is noted directly.

January – February

Both sides of the state are mostly dormant outdoors, but January is the start of the indoor seed-starting season. Start long-day onion varieties and leeks in early January — they need 10–12 weeks before transplanting. Start celery, celeriac, and peppers indoors in mid-to-late January. In Western Washington, cold-hardy greens like spinach, mâche, and claytonia can be sown under a cold frame or unheated hoop house by late February.

March

March is the most active outdoor month for Western Washington gardeners. If you are setting up new raised beds this spring, use our raised bed soil calculator to get the exact soil mix volume before you buy. As soon as soil is workable — typically early March in sheltered lowland gardens — direct sow peas, spinach, arugula, radishes, carrots, beets, and chard. Start tomato transplants indoors this month. In Eastern Washington, outdoor sowing should wait for late March; late frosts remain common through the first half of the month.

April

In Western Washington, April is transplant month for hardened-off brassicas, onion sets, and leeks. Continue direct sowing carrots, beets, and salad greens. Plant sweet peas and pansies outdoors — they thrive in cool April weather. Do not plant tomatoes or peppers outdoors yet. Cold soil below 60°F stunts warm-season crops even without frost — patience is worth more than optimism here. In Eastern Washington, April marks the start of cool-season outdoor sowing in earnest.

May

Late May is the transition point for warm-season planting across Washington. In Western Washington, transplant tomatoes, peppers, cucumbers, and basil outdoors after nighttime temperatures consistently hold above 50°F — Memorial Day weekend is the reliable benchmark most experienced local gardeners use. Direct sow beans and summer squash. This is also a good time to top up bed pathways and borders — our mulch calculator will tell you exactly how many bags or cubic yards you need. In Eastern Washington, mid-May works for warm-season transplants in warmer areas like Yakima and the Tri-Cities; Spokane should wait until after May 15.

June

June is full production and succession planting. Sow beans every 2–3 weeks through July for continuous harvest. In Eastern Washington, begin consistent deep irrigation as summer heat arrives — water at the base of plants, not overhead.

July – August

While summer crops produce, July and August are the critical windows for fall garden planting in Western Washington. Start fall broccoli, kale, chard, and Asian greens indoors in early July, then transplant outdoors by August. Direct sow spinach, arugula, and turnips in August for fall harvest. These crops will establish before days shorten and can produce through late fall — or through winter under minimal cover.

September – October

September still allows fast-maturing crops in Western Washington — lettuce, radishes, and spinach started now will produce before hard frosts. October is garlic month across the state. Plant hardneck varieties like Rocambole, Porcelain, or Purple Stripe for summer harvest. Plant spring-flowering bulbs (tulips, daffodils, alliums) through October and sow cover crops across empty beds.

November – December

Hardy overwintering crops — leeks, kale, Brussels sprouts, chard — continue growing slowly in Western Washington under minimal cover. Eastern Washington gardens are dormant. Order seeds, review what worked, and plan next year’s crop rotations.

Washington State Herb Planting Calendar

Washington’s cool maritime climate suits many culinary herbs but challenges heat-lovers like basil. Here’s the Washington herb planting calendar for both regions.

Herb	Plant Time (W. WA)	Plant Time (E. WA)	Notes
Basil	Late May–June	Late May–June	Most cold-sensitive; do not rush outdoors
Parsley	Mar–Apr (transplant)	Apr–May	Slow germinator; start indoors 8 wks early
Cilantro	Mar–May; Aug–Sept	Apr–May; Aug	Cool-season; bolts fast in heat
Dill	Apr–June	Apr–June	Direct sow only; resents transplanting
Chives	Mar–Apr	Apr–May	Hardy perennial; overwinters in WA
Mint	Apr–May	May	Plant in containers; spreads aggressively
Rosemary	Apr–May (sheltered)	May–June	Marginal in E. WA winters; mulch heavily
Thyme / Oregano	Apr–May	May	Hardy perennials once established
Lavender	Apr–May	May	Thrives in E. WA dry heat; struggles in wet W. WA
Sage	Apr–May	May	Drought-tolerant; excellent in E. WA

When to Plant Flowers in Washington State

Washington’s cool wet springs produce outstanding results for cold-tolerant annuals, and the warm days / cool nights of summer create ideal conditions for dahlias and sweet peas that would struggle in hotter climates.

Flower	Plant Time	Bloom Time	Notes
Sweet Peas	Feb–Mar (W. WA)	May–July	Sow very early; hate summer heat
Pansies / Violas	Feb–Apr (transplant)	Spring–Fall	Cold-hardy; thrives in WA spring conditions
Snapdragons	Feb–Mar indoors; Apr transplant	May–July	Cool-tolerant; outstanding cut flower
Lobelia / Alyssum	Mar–Apr (transplant)	May–Sept	Good cool-season performers
Nasturtiums	Apr–May (direct sow)	June–Oct	After last frost; very easy
Cosmos	May–June (direct sow)	Aug–Oct	Self-seeds reliably across WA
Zinnias	Late May–June	July–Oct	Need warmth; don’t rush in W. WA
Marigolds	May–June	July–Frost	Wait for consistently warm nights
Sunflowers	May–Early June (direct sow)	Aug–Sept	After soil warms to 60°F
Dahlias (tubers)	May–June	Aug–Frost	W. WA’s signature summer flower; dig in fall
Impatiens / Begonias	Late May (transplant)	June–Frost	Wait for warm nights in W. WA
Tulips / Daffodils	Oct–Nov (fall bulb planting)	Mar–May	Plant in fall for spring bloom
Alliums	Oct–Nov (fall)	May–June	Excellent in both WA regions

Dahlias deserve a special note. Western Washington’s cool nights and warm days produce some of the most spectacular dahlia blooms in the country — a few dinner-plate varieties in late May will convert you by August.

Common Planting Mistakes Washington Gardeners Make

TIMING MISTAKES TO AVOID These errors come up consistently — in print, in extension offices, and in real gardens across both sides of the state.

Planting tomatoes in April.  The single most widespread mistake in Western Washington. April soil temperatures hover in the low 50s°F — tomatoes planted then don’t die, they just sit there for weeks, not growing. A tomato transplanted in late May into warm soil will frequently catch and surpass an April-planted one by August. Patience wins every time.

Skipping hardening off.  Seedlings moved directly from a warm indoor environment to outdoor conditions — wind, UV, temperature swings — routinely suffer transplant shock even when frost risk is past. Give transplants 7–10 days of gradually increasing outdoor time before planting permanently.

Treating average frost dates as deadlines.  Average last frost dates represent the midpoint of a historical range, not a guarantee. Late cold snaps in the Columbia Basin and mountain-adjacent areas can surprise experienced gardeners well into May. Watch the forecast; don’t just trust the calendar.

Ignoring soil temperature.  Soil temperature controls germination and root growth. A simple $15 soil thermometer is one of the most useful tools in a Washington garden. Cool-season crops germinate at 40–55°F; warm-season crops need 65°F or above, consistently.

Starting peppers and tomatoes the same week.  Peppers need 10–12 weeks indoors; tomatoes need 8–10 weeks. Starting both in mid-March means tomatoes become root-bound and leggy while peppers are still small. Start peppers 2–3 weeks before tomatoes.

Not succession planting cool-season crops.  One batch of lettuce in April creates a glut in June and nothing by September. Sow salad greens every 3–4 weeks from March through September for harvests all season.

Washington State Seasonal Garden Planting Checklist

January – February

• Order seeds; review last year’s notes and plan crop rotation
• Start onions and leeks indoors (early January)
• Start celery, celeriac, peppers, and eggplant indoors (mid–late January to early February)
• Set up grow lights — essential for strong seedlings before April
• Amend garden beds with compost when ground is accessible — use our compost calculator to measure the right amount for your bed size

March – April

• Direct sow peas, spinach, arugula, radishes outdoors (W. WA: March; E. WA: late March)
• Start tomatoes, brassicas, and cool-season annual flowers indoors
• Transplant hardened-off brassicas, onions, and leeks outdoors
• Check soil temperature before any direct outdoor sowing
• Plant sweet peas and pansies outdoors in W. WA

May – June

• Transplant tomatoes and peppers after last frost (W. WA: late May; E. WA: mid-May)
• Direct sow beans, summer squash, cucumbers after frost passes
• Plant dahlia tubers, zinnias, and warm-season annual flowers
• Begin succession sowing of beans and salad greens
• Harden off all transplants for 7–10 days before permanent planting

July – August

• Start fall brassicas and kale indoors (early July)
• Direct sow fall spinach, arugula, and turnips (late July–August)
• Harvest regularly to keep plants producing
• Water consistently and deeply in Eastern Washington as heat peaks

September – November

• Transplant fall brassicas; sow fast greens for fall harvest (September)
• Plant garlic (October–November)
• Plant spring bulbs — tulips, daffodils, alliums (October)
• Sow cover crops across empty beds through October
• Dig and store dahlia tubers after first frost (W. WA)

How to Use This Washington State Planting Calendar

1. Find your USDA hardiness zone. Enter your zip code at planthardiness.ars.usda.gov to confirm your zone and whether you’re in a western or eastern climate pattern.
2. Look up your local last spring frost date. Use your county’s WSU Extension website. Write it down — it’s the anchor date for everything else.
3. Count backward for indoor seed starts. If your last frost is May 10 and tomatoes need 8–10 weeks indoors, count back to early-to-mid March as your start date.
4. Check soil temperature before direct sowing. Use a soil thermometer at 2-inch depth. Cool-season crops germinate at 40–55°F; warm-season crops need 65°F or above.
5. Plan succession plantings. Decide which crops you want continuously (salad greens, beans, radishes) and schedule new sowings every 3–4 weeks throughout the season.
6. Harden off all indoor-started transplants. Bring them outside for gradually increasing time over 7–10 days before permanent planting.
7. Keep a simple planting journal. Note planting dates, transplant dates, first harvest, and any weather anomalies. Three seasons of notes will improve your planting decisions more than any guide.

Key Takeaways

• Washington State’s climate divides at the Cascades — gardening timelines on the west and east sides differ by 4–8 weeks for most warm-season crops.
• Your local last spring frost date is the single most important number for planting timing — look it up by city, not by region.
• In Western Washington, warm-season transplants (tomatoes, peppers, basil) belong outdoors in late May, not April — regardless of warm spells earlier in spring.
• Grow lights are not optional for indoor seed starting in Washington — winter light levels are insufficient for strong, healthy seedlings without supplemental lighting.
• Western Washington’s long cool season is an underused advantage — succession-plant cool-season crops from March through September for continuous harvests.
• Dahlias, sweet peas, kale, and brassicas thrive in Washington’s climate — lean into what the region does naturally well rather than fighting it.
• Soil temperature matters more than air temperature for germination timing — use a thermometer, not just a calendar.

More State Planting Calendars
→ Florida Planting Calendar
→ Texas Planting Calendar
→ Arizona Planting Calendar
→ Ohio Planting Calendar
→ Michigan Planting Calendar

Frequently Asked Questions Washington Planting Dates

This guide draws on USDA hardiness zone data, WSU Extension horticulture recommendations, NOAA climate normals, and the accumulated experience of Pacific Northwest home gardeners. Conditions vary by microclimate — always observe your specific site and adjust accordingly.