When to Plant Broccoli in Maine
Published: April 21, 2026
Maine gardeners in Zone 5a have a 26-week frost-free window for broccoli (April 15 to October 15). Cool-season crops like broccoli do well here because the short, cool summers match the plant's temperature preferences naturally. This guide gives exact dates for Maine based on your local frost calendar.
Broccoli Planting Dates for Maine
| Start seeds indoors | March 4–11 |
| Last frost (average) | April 15 |
| Transplant outdoors | March 18–28 |
| Direct sow outdoors | March 18–28 |
| Expect first harvest | May 17 – June 6 |
| Fall crop start | August 6–16 |
| Fall harvest | October 5 |
| First fall frost (average) | October 15 |
Growing Broccoli in Maine's Climate
Maine's cold Zone 5a climate is close to ideal for broccoli. 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 broccoli crop in Maine 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 broccoli pests to watch for in Maine include Cabbage Worm and Cabbage Looper. The first line of defense is companion planting: Onion and Garlic 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.
Broccoli Garden Calendar for Maine
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | — | Dormant season |
| March | Transplant outdoors | Soil temp must be 40°F+; nighttime lows above 50°F |
| April | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| May ← | Watch for bolting | Harvest promptly; spring heat arrives quickly |
| June | — | Dormant season |
| July | — | Dormant season |
| August | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| September | — | Dormant season |
| October | First frost approaches | Harvest remaining broccoli; cover plants on frost nights |
| November | — | Dormant season |
| December | — | Dormant season |
Broccoli Growing Tips for Maine Gardeners
- •For spring: start indoors 6 weeks before last frost and transplant outdoors 4 weeks before last frost.
- •For fall: start indoors in summer — count 10 weeks back from your first fall frost date.
- •Maine'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.
- •Harvest heads before any yellow flowers open — once flowers show, flavor declines quickly.
Companion Planting for Broccoli in Maine
In Maine's cold climate, planting broccoli with Onion and Garlic helps deter pests and improve soil. Avoid planting near Tomato and Pepper, which inhibit broccoli growth through root chemistry or shared pest pressure. See the full broccoli companion planting guide for the complete list.
Broccoli Planting Dates by City in Maine
Top cities in Maine — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant broccoli in Maine?
In Maine (Zone 5a), start broccoli seeds indoors around March 4–11 and transplant outdoors around March 18–28 — 4 weeks before the state's average last frost of April 15.
What is the last frost date in Maine?
Maine's average last frost date is April 15 in the state's most common Zone 5a. 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 broccoli year-round in Maine?
broccoli is a cool-season crop in Maine, 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 broccoli varieties grow best in Maine?
For Maine's Zone 5a, De Cicco and Waltham 29 tolerate cold and produce secondary side shoots after main head harvest.
When do I start broccoli seeds indoors in Maine?
Start broccoli seeds indoors in Maine around March 4–11, which is 6 weeks before the state's average last frost of April 15. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.