Tomatoes hit the dirt, peas hit the peak — the great Portland handoff.
Knowing what to plant in Portland in mid-May is the difference between a vegetable garden that limps into June and one that explodes by July. Nights are finally holding above 50°F, soil temps are creeping into the 60s, and the spring crops are racing to bolt. This is the pivot week — cool-season harvests come out, warm-season transplants go in.
This Week's Action List
- Transplant tomato starts now that nights are reliably above 50°F. Bury stems up to the first true leaves for stronger roots, and stick with proven Zone 8b performers like Sungold, Early Girl, Stupice, and Oregon Spring from Portland Nursery or Cornell Farm.
- Check soil temperature at 4 inches deep with a probe thermometer before direct-sowing beans, squash, and cucumbers. Wait for a steady 60°F — Eastside beds usually hit it this week, but shaded West Hills gardens may need another 7 to 10 days or a layer of black plastic to warm up.
- Harvest snap peas, spinach, lettuce, and radishes every two to three days. Heat above 75°F triggers bolting fast, so pick young and pick often, then succession-sow heat-tolerant lettuces like Jericho or Nevada to extend the salad season into June.
- Hold off on basil until next week if nights are still dipping into the high 40s — it sulks below 50°F and may never recover. When you do plant, give Genovese and Thai basil a warm spot near the tomatoes and pinch the top set of leaves at 6 inches to force bushy growth.
- Set out slug bait or shallow beer traps around every new transplant. Portland's slug population is wide awake, and a single night can erase a tray of squash seedlings — iron phosphate pellets are pet-safe and rain-tolerant after our recent showers.
Frequently Asked Questions
When is it safe to plant tomatoes outside in Portland Oregon?
After May 15 is the traditional Portland rule, once nighttime lows stay above 50°F consistently. If a cold snap is forecast, cover transplants with row cover or a cloche — tomatoes stall below 50°F even if they survive.
What vegetables can I direct sow in Portland in May?
Once soil hits 60°F, direct sow bush and pole beans, summer and winter squash, cucumbers, and a final round of carrots and beets. You can also still sow lettuce, chard, and bunching onions for ongoing harvests through early summer.