Regional Planting Calendar – What To Plant In May In Northwest Gardens

Tiny Sprouting Plants
(Image credit: tortoon)

Spring has arrived and it’s time to get a head start on planting in most regions of the mild, rainy Pacific Northwest. What to plant in May? The regional planting calendar is wide open. 

Read on for tips and suggestions on Northwest planting in May. If you aren't sure about what to plant in May, your local cooperative extension can offer suggestions.

What to Plant In May: Flowers For Planting In The Northwest

May is ideal for planting annuals across most of the Northwest, but remember that nights may still be frosty in eastern Oregon and Washington. 

You can get a head start with small plants from a garden center or nursery, but several annuals, including zinnias, marigolds, cosmos, and asters can be direct-planted by seed.

You’re missing out if you haven’t planted northwest natives. The following native perennials are easy to grow, require very little water or fertilizer once established, and will attract honeybees and other pollinators. 

  • Lupine (Lupinus latifolius), which reaches heights of 2 feet (60 cm.), will thrive in a sunny spot in the back of a bed. Native to western North America, lupine produces attractive foliage and bluish-purple flowers in late spring. Zones 6-10. 
  • Blanket flower (Gaillardia aristata) is a drought-tolerant prairie native that has naturalized across much of North America. With regular deadheading, you’ll enjoy bright yellow and reddish-orange flowers all summer. Zones 4-10.
  • Sting shootar (Dodecatheon pulchellum) is native to the Northwest’s prairies and alpine meadows. The delicate flowers show up in spring, and then the plant goes dormant with the arrival of warmer weather. Zones 3-7.
  • Siskiyou lewisia (Lewisia cotyledon) is native to the subalpine climates of southern Oregon and Northern California. The incredible showy blooms are pale pink or white with contrasting veins. Zones 6-8.

Northwest Planting In May: Vegetables

In Western Oregon and Washington, the weather is suitable for planting nearly any vegetable, including leafy greens like arugula, kale spinach, and lettuce; root vegetables like beets, turnips, and carrots, and garden standards such as beans, cukes, peas, radishes, melons, summer squash and winter squash. Gardeners in higher elevations should wait a little longer.

May is also time to plant tomatoes and peppers west of the Cascades, but on the east side, you’ll want to wait until you’re sure you’re past any danger of frost. Both need plenty of warmth and sunlight. 

Plant herbs as soon as the soil warms. Include fennel, yarrow, borage, anise, hyssop and dill, as they will attract beneficial insects that keep pests in check.

Mary H. Dyer

A Credentialed Garden Writer, Mary H. Dyer was with Gardening Know How in the very beginning, publishing articles as early as 2007.