Outdoor Grow Guide
Best Cannabis Seeds for Outdoor Growing in Washington
Your growing season is 175 days. Last frost: Apr 28. First frost: Oct 20. Here are the strains that will actually finish in time.
Find My StrainsCool summers and fall overcast can slow finish and invite mold. Choose mold-resistant genetics that handle September rain; plan harvest before coastal fog arrives.
Matched Strains
Top Strains for Washington
Season Timeline
Washington Grow Calendar
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Common Questions
Washington Outdoor Growing FAQ
Washington's climate is forgiving in some ways, brutal in others
Washington sits in USDA hardiness zone 7a (ranging 4a-9a across the state) with an average growing season of 175 days — from last frost around Apr 28 to first frost around Oct 20. The Pacific Northwest offers mild summers but notorious fall rain and overcast skies that threaten late finishers.
The primary constraint for outdoor cannabis growers in Washington is matching strain finish time to the frost window. With 175 days, you have room for most strains — but selecting genetics that finish comfortably before Oct 20 is still the difference between success and a crop cut short.
The 3 challenges specific to Washington growers
- Fall rain and mold: September and October bring the rain back to the Pacific Northwest. Any strain finishing after mid-September is at elevated bud rot risk. Prioritize mold resistance (rated 4–5) and be prepared to harvest early if weather turns.
- Cool summer temperatures: Unlike California, the Pacific Northwest has genuinely cool summers. Average July highs in western Washington and Oregon rarely exceed 80°F. This slows growth compared to warmer climates — factor in an extra 1–2 weeks for finish time.
- Maritime overcast: Coastal fog and overcast skies reduce light hours even in summer. This can delay the natural flip to flowering in photoperiods. Inland growing locations outperform coastal sites significantly.
When to start in Washington
The Washington outdoor season follows a predictable rhythm tied to frost dates:
- Germinate indoors: Around Mar 29 — 30 days before last frost. This gives seedlings time to establish before facing outdoor conditions.
- Transplant outdoors: Around May 5, one week after the average last frost passes. Wait for consistent overnight lows above 50°F.
- Vegetative growth: Plants grow vigorously from transplant through mid-July under long summer days (up to 15.8h at solstice).
- Flower trigger: Around July 21, declining day length naturally initiates flowering in photoperiod strains.
- Harvest window: Strain-dependent, but target completion by Oct 6 — 14 days before average first frost — to avoid late-season stress.
Outdoor vs greenhouse in Washington
Outdoor growing without season extension is perfectly viable in Washington for most strains. A simple hoophouse or cold frame can add 2–3 weeks to your season at either end, which opens up longer-flowering photoperiods that wouldn't reliably finish without it. If you're growing late-finishing genetics, a basic season extender is a worthwhile investment.
Legal status of home growing in Washington
Home growing laws vary significantly by state and change frequently. Before growing cannabis outdoors in Washington, verify the current regulations for your county. Many states that have legalized adult use cannabis still prohibit or limit home cultivation. Always grow within the law — check your state's official cannabis regulatory agency for current rules.