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Close-up of fresh basil leaves
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When to plant basil in Roseburg, OR

Start basil from seed indoors Mar 29 – Apr 12, then plant the young plants in the garden in Roseburg May 10 – Jun 7.

Moderate Plant young plants (starts)

Difficulty
Moderate
Sun
Full sun
Spacing
12 inches apart
Planting depth
Plant starts at the depth they grew in the pot
Frost
Killed by frost
First harvest
About 60 days after planting

Why these dates

Roseburg's typical last spring frost is March 19. Frost kills basil, 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.

How to grow basil in Roseburg

  1. Start seeds indoors Mar 29 – Apr 12 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 – Jun 7, 12 inches apart. Plant starts at the depth they grew in the pot.
  4. Water deeply once or twice a week rather than a little every day, and mulch once the soil is warm.
  5. Harvest: Pinch off the top pair of leaves often so plants bush out, and remove flower buds.

Key numbers

How it works

The plant biology behind the advice above, in plain language.

A tropical plant in a cool climate

Basil is a tropical plant, and cold damages it even without frost. Below about 50°F the leaves can develop dark spots and blacken a few days later, and growth stalls. Seeds sprout best in soil around 70 to 85°F. In the Northwest, that means waiting until nights stay above 50°F, usually June west of the Cascades, or growing it in a greenhouse or a warm, sheltered spot.

Pinching and flowering

Pinch off the top pair of leaves above a pair of side shoots when plants are 6 inches tall, and keep pinching. Each pinch makes two new shoots and a bushier plant. Once basil flowers, it shifts energy to seeds, leaf production slows and the flavor changes, so pinch off flower buds as soon as they appear.

Soil and water

Basil likes rich, well-drained soil with a pH of about 6.0 to 7.0, full sun and steady moisture. Water at the base in the morning. Wet leaves overnight encourage disease. In containers, use a large pot so the soil doesn't dry out by afternoon.

Downy mildew

Basil downy mildew spread across North America in the late 2000s. Leaves yellow between the veins, and a gray-purple fuzz forms on the undersides, especially in humid weather. Classic Genovese is very susceptible. Resistant varieties like Prospera and Amazel hold up much better, and the Rutgers DMR varieties are moderately resistant. Pull infected plants promptly.

Harvest and storage

Harvest by cutting stems just above a pair of leaves. Don't refrigerate fresh basil: cold blackens it. Keep cut stems in a glass of water on the counter like flowers, or blend it into pesto or oil and freeze it.

Common questions

When is the last frost in Roseburg, OR?

Typically March 19. In 9 years out of 10, frost is over by April 13. These are 1991–2020 NOAA climate normals for Roseburg Regional Airport.

Is it too late to plant basil in Roseburg?

The spring planting window runs through June 7. Later plantings may not have time to produce before the first fall frost, which usually arrives around November 20.

When should I start basil from seed indoors in Roseburg?

March 29 to April 12, which is 6 to 4 weeks before the May 10 planting date. Or buy young plants at a garden center instead.

Why is my basil turning black?

Cold. Basil is damaged below about 50°F, even without frost, and the leaves blacken a few days later. Keep it outside only when nights are warm, and never store fresh basil in the fridge.

Why are my basil leaves yellow with fuzz underneath?

That's basil downy mildew. Pull infected plants, water at the base in the morning, and grow resistant varieties like Prospera or Amazel next time.

Can I keep basil alive over winter?

Basil is grown as an annual and usually declines indoors in winter's low light. You can root cuttings in water in late summer and grow them on a sunny windowsill or under a grow light, but new seedlings in spring usually do better.

Also plant in Roseburg around the same time

Planting dates for basil in nearby areas

Full planting calendar for Roseburg · Basil in every city