When should I plant Broccoli in Zone 4a?

Start Broccoli seeds indoors around Mar 24. Transplant outdoors after May 19. Expect first harvest around Jul 18.

What is the last frost date for Zone 4a?

The average last spring frost date for Zone 4a is May 5. The first fall frost averages Oct 1, giving a 149-day growing season.

Can I grow Broccoli in Zone 4a?

Yes. Broccoli needs 70 days to harvest. Zone 4a has a 149-day growing season, which is sufficient.

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🥦 Growing Broccoli in Zone 4a

Zone 4a has cold winters and a moderate growing season. Timing is key for Broccoli in this zone. Last frost: May 5. First frost: Oct 1.

Planting Calendar

Indoor

Outdoor

Harvest

Mar 24Oct 1

Season: May 5 – Oct 1 (149 days)

Zone4a

Last FrostMay 5

First FrostOct 1

Season Length149 days

Days to Harvest70

SunFull Sun

Frost ToleranceHeavy

Spacing1/sqft (12" apart)

When to Plant Broccoli in Zone 4a

Start Seeds Indoors: Mar 24

Start Broccoli seeds indoors around Mar 24 (6 weeks before last frost). Optimal germination temperature: 75°F. Germinates in 5–10 days.

Transplant Outdoors: May 19

Transplant Broccoli seedlings outdoors after May 19. Wait until soil temperature reaches 50°F. Space plants at 1/sqft (12" apart). Harden off plants for a week before moving outside.

Harvest: Jul 18

First harvest approximately Jul 18 (~60 days from transplant). Continue harvesting until first frost (Oct 1).

Fall Planting: Jul 9

For a fall harvest, plant Broccoli around Jul 9 (12 weeks before first frost).

Companion Planting

✅ Sage ✅ Rosemary ✅ Mint ✅ Chamomile ✅ Dill

❌ Strawberries❌ Tomatoes❌ Beans

Broccoli in Other Zones

1a 1b 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b 11a 11b 12a 12b 13a 13b

Plan Your Broccoli Garden

Track Broccoli from seed to harvest with personalized frost dates, watering recommendations, and companion planting visualization.

Start Free Broccoli Growing Guide