When to Plant Annuals in Washington – 2026
Published: April 27, 2026
Washington sits in USDA Zone 8a (population-weighted primary). Plant annuals in Washington from March through July. Average last spring frost: February 15; first fall frost: December 1; frost-free growing season: 289 days. The bloom season for annuals is summer through fall.
Annuals Planting Dates in Washington
Plant warm-season annuals (petunias, zinnias, impatiens, begonias) after last frost when soil reaches 15°C / 60°F. Cool-season annuals (pansies, snapdragons, alyssum) can be planted 2–4 weeks before last frost. Start from seed indoors 6–8 weeks before transplanting.
For Washington specifically, the recommended planting window is March through July. This window is based on the state's population-weighted USDA Zone 8a — but Washington spans multiple climate zones, so adjust based on your local conditions. Coastal, mountain, and inland areas within Washington can vary by 2 to 4 weeks from the state average. The 289-day frost-free growing season in Washington is nine and a half months frost-free. warm-season grasses go dormant only briefly if at all.
Always check current local forecasts before planting frost-sensitive species. The 'last frost date' is an average — actual frost can occur 2 weeks after the average date in cold years. For warm-season annuals (petunias, zinnias, marigolds), wait at least 1 week past the average last frost date to ensure consistently warm soil. For cool-season annuals (pansies, snapdragons), planting 2 to 4 weeks before last frost is appropriate.
Best Annuals Varieties for Washington
For Washington Zone 8a, choose varieties rated for your zone or one zone colder for reliable performance. Below are the top annuals cultivars suitable for Washington's climate.
Most popular bedding annual. Continuous bloom from late spring through frost. Sun, deadhead spent blooms (or use Wave or Supertunia self-cleaning types).
Direct-sow after last frost. Drought-tolerant, prolific bloomer through fall. Cut-flower champion. Powdery mildew resistant cultivars (Profusion, Zahara).
Standard shade annual. New Guinea types tolerate more sun. Continuous bloom through fall.
Sun or part shade depending on type. Wax begonias are nearly indestructible bedding annuals. Tuberous types prefer shade with cool nights.
Plant 2 to 4 weeks before last frost or in fall. Tolerate frost down to -7°C (20°F). Bloom during cool weather; die or decline in summer heat.
How to Plant Annuals in Washington
Sow method for annuals: transplant or direct. The practical steps below apply to Washington's climate and the typical first-year planting timeline.
- →Warm-season annuals: plant after last frost when soil reaches 15°C (60°F).
- →Cool-season annuals: plant 2 to 4 weeks before last frost or in fall (Zone 7+) for spring or winter color.
- →For earliest blooms, start seeds indoors 6 to 8 weeks before last frost; transplant after frost.
- →Choose full sun for most annuals (zinnias, marigolds, petunias) and part shade for shade-loving types (impatiens, begonias).
- →Space according to mature size — typically 25 to 30 cm (10 to 12 inches) for most bedding annuals.
- →Water at the base; avoid overhead watering which promotes powdery mildew on zinnias.
- →Apply slow-release fertilizer at planting; supplement with weekly liquid feeding during peak growth.
- →Deadhead spent blooms weekly to extend the flowering period (skip for self-cleaning Wave petunias and triploid marigolds).
Annuals Care Calendar for Washington
Spring (Washington last frost: February 15): The main planting window opens after last frost when soil reaches 10°C (50°F). For warm-season annuals, wait at least 1 week past last frost. Apply slow-release fertilizer at planting for first-season vigor.
Summer: Water consistently for the first month after planting; established plants need watering only during extended dry periods. Peak bloom for warm-season annuals.
Fall (Washington first frost: December 1): Final blooms before first frost — no fall planting recommended for warm-season annuals. Apply final mulch layer after first hard frost.
Winter: Mild winter conditions — many flowers continue blooming or remain semi-evergreen. Cool-season annuals (pansies, snapdragons) provide color through winter.
Frequently Asked Questions about Annuals in Washington
When should I plant annuals in Washington?
Plant annuals in Washington from March through July based on the state's primary USDA zone (8a). Plant warm-season annuals (petunias, zinnias, impatiens, begonias) after last frost when soil reaches 15°C / 60°F. Cool-season annuals (pansies, snapdragons, alyssum) can be planted 2–4 weeks before last frost. Start from seed indoors 6–8 weeks before transplanting.
What USDA zone is Washington?
Washington spans multiple USDA zones, but the population-weighted primary zone is 8a. The state's average last spring frost is around February 15 and first fall frost around December 1, giving a frost-free growing season of about 289 days. Adjust planting dates based on your specific local microclimate — coastal, mountain, and inland areas within the state can vary by 2 to 4 weeks from the state average.
Which annuals varieties grow best in Washington?
For Washington (Zone 8a), choose varieties rated for your zone or one zone colder for reliable winter survival. Petunias (Petunia × hybrida) (All zones, warm-season) is widely planted across most US zones. Zinnias (Zinnia elegans) is another strong choice (All zones, warm-season). Match the variety to your specific microclimate and sun exposure for best results.