Washington Planting Dates, Frost Dates & Growing Season

Washington Spring Planting Windows

A practical guide to when planting usually works in Washington. These windows are based on climate normals (not a forecast) and line up with the 50% last spring frost and typical early-season heat.

How the Growing Season Works in Washington

Washington usually has a relatively forgiving season, but results still depend on how quickly gardens warm in spring and how well crop choices match local conditions.

• Stagger planting dates: spreading sowings and transplanting windows often works better than planting everything at once.
• Fall planting is more realistic: many areas still have enough runway for a meaningful second round of faster crops.
• Summer management becomes the limiter: water, fertility, and pest pressure often matter more than season length alone.

Microclimate note: frost timing varies widely across Washington, so sheltered gardens, urban sites, and warmer exposures can behave very differently from colder open areas.

Late-summer note: there is often still meaningful heat left around early August, so second plantings of faster crops can still be worthwhile.

Remaining Season Heat in Washington (Base 50 GDD)

Growing Degree Days (Base 50°F) measure heat accumulation. “Remaining GDD” shows how much usable heat is typically still available from a given date onward in a normal season.

Use these values to judge whether a crop or variety still has enough heat left after planting. This is especially helpful for later sowings, shorter-maturity choices, and deciding whether a second round is realistic.

Typical Season Rhythm

A practical “typical year” rhythm for planning. Use it as a baseline, then adjust for microclimates and variety maturity.

Typical season length: 191 frost-free days between the median spring and fall frost dates.

How Growing Conditions Vary Across Washington

Growing conditions often vary more within Washington than most gardeners expect. Differences in elevation, exposure, cold-air drainage, and nearby pavement or buildings can shift frost timing and change how much usable season you really have.

• Frost timing varies widely across the region, especially between colder pockets and more sheltered sites.
• Earlier-frost and shorter-season locations usually need faster-maturing crops and tighter planting timing.
• Warmer locations usually retain more remaining heat through the season, giving longer-season crops and later plantings better odds of finishing.
• Urban areas, walls, and sheltered gardens usually stay warmer than open rural or wind-exposed sites.
• Cold air settles in low spots, so slightly elevated beds often avoid the earliest frosts.
• South- and west-facing areas usually warm sooner in spring and can stay productive later into fall.

How Gardeners Adapt

Experienced gardeners in Washington usually adjust their timing and crop choices to match how the season actually behaves, not just the calendar.

• Using row cover or low tunnels to smooth out temperature swings early and late in the season.
• Succession planting fast crops to keep beds productive through summer.
• Watching local conditions closely and adjusting timing year by year.

Common Timing Mistakes

These patterns show up again and again in Washington — especially in typical years.

• Planting everything at once instead of staggering crops across the season.
• Assuming conditions are uniform across the region — frost timing often varies widely by elevation, exposure, and shelter.
• Relying on calendar dates instead of crop maturity and typical frost timing.