When to Plant Cauliflower in Oregon
Published: April 24, 2026
Oregon gardeners in Zone 4b have a 21-week frost-free window for cauliflower (May 7 to October 1). Cool-season crops like cauliflower do well here because the short, cool summers match the plant's temperature preferences naturally. This guide gives exact dates for Oregon based on your local frost calendar.
Cauliflower Planting Dates for Oregon
| Start seeds indoors | April 2–9 |
| Last frost (average) | May 7 |
| Transplant outdoors | April 16–26 |
| Expect first harvest | June 10 – July 25 |
| Fall crop start | July 23–August 2 |
| Fall harvest | September 16 |
| First fall frost (average) | October 1 |
Dates above assume Zone 4b, the most common zone in Oregon. Gardeners in cooler Portland (Zone 4b) plant 1–2 weeks later; warmer Medford (Zone 5b) can plant 1–2 weeks earlier.
⚠ Start cauliflower indoors 4–6 weeks before last frost. Transplant 2–4 weeks before last frost. Needs consistent moisture and cool temps — bolts in heat above 75°F.
Growing Cauliflower in Oregon's Climate
Oregon's cold Zone 4b climate is close to ideal for cauliflower. The cool springs and moderate summers match the plant's natural temperature preferences, producing crisp, sweet, slow-bolting harvests that hot-climate gardeners cannot grow.
The fall cauliflower crop in Oregon is often better than the spring crop. Plants mature as temperatures cool in September and October, concentrating sugars and tightening heads or roots. Light frost can improve flavor; hard frost signals harvest time.
Common cauliflower pests to watch for in Oregon include Cabbage Worm and Cabbage Looper. The first line of defense is companion planting: Onion and Celery planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Cauliflower Garden Calendar for Oregon
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | — | Dormant season |
| March | — | Dormant season |
| April | Transplant outdoors | Soil temp must be 45°F+; nighttime lows above 50°F |
| May ← | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| June | First harvest window opens | Cauliflower begins producing 55–100 days after transplant |
| July | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| August | — | Dormant season |
| September | — | Dormant season |
| October | First frost approaches | Harvest remaining cauliflower; cover plants on frost nights |
| November | — | Dormant season |
| December | — | Dormant season |
Cauliflower Growing Tips for Oregon Gardeners
- •Blanch white varieties by tying outer leaves over the head when it reaches egg-size — prevents yellowing from sun exposure.
- •Keep soil evenly moist — drought stress causes small, bitter 'buttoning' heads instead of full curds.
- •Oregon's short growing season means start seeds indoors under grow lights — don't rely on windowsill light which produces leggy, weak seedlings that struggle outdoors.
- •Cover young transplants with floating row covers for the first 2–3 weeks outside. The 3–5°F of protection reduces frost damage risk and accelerates early growth.
- •Plant fall crops in mid-July to mid-August for October harvest; fall cauliflower is usually larger and sweeter than spring.
Companion Planting for Cauliflower in Oregon
In Oregon's cold climate, planting cauliflower with Onion and Celery helps deter pests and improve soil. Avoid planting near Tomato and Strawberry, which inhibit cauliflower growth through root chemistry or shared pest pressure. See the full cauliflower companion planting guide for the complete list.
Cauliflower Planting Dates by City in Oregon
Top cities in Oregon — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant cauliflower in Oregon?
In Oregon (Zone 4b), start cauliflower seeds indoors around April 2–9 and transplant outdoors around April 16–26 — 3 weeks before the state's average last frost of May 7.
What is the last frost date in Oregon?
Oregon's average last frost date is May 7 in the state's most common Zone 4b. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow cauliflower year-round in Oregon?
cauliflower is a cool-season crop in Oregon, with spring and fall windows. Summer heat bolts the plants before they can produce a harvestable crop. Succession planting every 2–3 weeks stretches the harvest window.
What cauliflower varieties grow best in Oregon?
For Oregon's Zone 4b, consult a local nursery or extension office for cauliflower variety recommendations.
When do I start cauliflower seeds indoors in Oregon?
Start cauliflower seeds indoors in Oregon around April 2–9, which is 5 weeks before the state's average last frost of May 7. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.