Rainline Garden

When to plant melons in Portland, OR

Plant melons in the garden in Portland May 10–31, either as seeds or as young plants started indoors Apr 12–19.

Tricky here Plant seeds or young plants

Why these dates

Portland's typical last spring frost is March 13. Frost kills melons, and warm-season crops also need warm soil. Soil here stays cold for weeks after the last frost, so planting waits until about May 10.

West-side valleys. The Willamette Valley, Puget Sound and southern Oregon valleys. Long frost-free seasons, but soil stays cold and wet into May, so warm crops wait for warm soil, not just the last frost.

Difficulty
Tricky here
Sun
Full sun; the hottest spot you have
Spacing
24 to 36 inches apart
Planting depth
1 inch deep
Frost
Killed by frost
First harvest
About 85 days after planting

Step by step

  1. Start seeds indoors Apr 12–19 in trays or small pots under a grow light or in your sunniest window. Or skip this step and buy young plants (starts) at a garden center.
  2. Harden off the young plants: about a week before planting, set them outside for a few hours a day, a little longer each day.
  3. Plant them in the garden May 10–31, 24 to 36 inches apart. If you plant seeds instead, sow them 1 inch deep.
  4. Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
  5. Harvest: Cantaloupes are ripe when the stem slips off with a gentle push. Watermelons are ready when the curly tendril nearest the fruit turns brown and dry.

Varieties that do well here

  • Sugar Baby (watermelon)
  • Minnesota Midget (cantaloupe)
  • Halona (cantaloupe)

Watch out for

Cool soil and cool nights are the main obstacle west of the Cascades. Black plastic mulch and row cover until flowering make the difference.

The toughest heat lover for west-side gardens: choose short-season varieties and use black plastic and row cover. Eastern valleys grow them easily.

Common questions

When is the last frost in Portland, OR?

Typically March 13. In 9 years out of 10, frost is over by April 1. These are 1991–2020 NOAA climate normals for Portland International Airport.

Is it too late to plant melons in Portland?

The spring planting window runs through May 31. Later plantings may not have time to produce before the first fall frost, which usually arrives around November 19.

When should I start melons from seed indoors in Portland?

April 12 to April 19, which is 4 to 3 weeks before the May 10 planting date. Or buy young plants at a garden center instead.

Also plant in Portland around the same time

Planting dates for melons in nearby areas

Full planting calendar for Portland · Melons in every city