Seed Planting Dates for Tomatoes & Peppers in the Pacific Northwest

Pacific Northwest Climate

• The western half of Washington and Oregon has a maritime climate with mild year-round temperatures and plenty of rain. This rain largely expends itself over the Cascade Range as it moves inland, creating a drier and warmer eastern half of the inland Pacific Northwest. U.S. Department of Agriculture plant hardiness zones for the Pacific Northwest range from 4b to 9a, with minimum temperatures as low as -25 degrees Fahrenheit in the higher elevations and up to 20 degrees Fahrenheit in warmer areas. Washington State University Extension recommends "Stupice," "Sungold," "Early Girl" and "Early Swedish" as some tomato varieties that grow well in the Pacific Northwest. Oregon State University Extension Service suggests short-season bell pepper varieties: "Parks Early Thickset," "Early Cal Wonder 300," "Golden Bell," "Banana Supreme," "Gypsy," "Yankee Bell," "Northstar," "Bellboy," "Blue Star" and "Mogador."

Tomatoes

• With tomatoes’ (Solanum lycopersicum) long growing season and the late dates for air and ground temperatures to rise into the 60-degree-plus Fahrenheit range needed for this crop to thrive, you need to extend the growing season. Start the seeds indoors where you can keep them warm enough to grow to harvest before the cool temperatures return in the fall. According to OSU Extension Service, you should germinate the seeds indoors in late February-early March, eight weeks before the last expected spring frost. Keep them at 65 to 70 degrees Fahrenheit and they should germinate in six to 10 days. Repot them in a larger pot when the second set of true leaves appear and again when the plant reaches six to 10 inches tall and soil temperatures rise to 60 degrees Fahrenheit or more.

Peppers

• Peppers (Capsicum annuum and Capsicum frutescens) also require an extended growing season and indoor seeds start six to eight weeks before outdoor transplant. Maintain the seeds and seedlings at 70 to 85 degrees Fahrenheit. Transplant the seedlings to a larger container when the first true leaves are 1 1/2 inches long. Outdoor transplant is due when nighttime air temperatures reliably remain higher than 55 degrees Fahrenheit and soil temperatures warm to 70 to 75 degrees Fahrenheit.

Keeping Warm

• To reap a good harvest of your tomatoes and peppers when your growing season is short and cool, keeping them warm is critical to encouraging them to ripen before first frost. Warm your indoor seed starts with heat lamps, fluorescent lights, a bottom-heating pad and cover. After transplant, you can help your heat-loving crops thrive by using black plastic soil covers or planting them under a cloche wire cage wrapped in clear plastic.