Fall is the best season to grow broccoli. Unlike spring crops that often rush to flower as temperatures rise, fall broccoli matures as the weather cools, producing larger heads, tighter florets, and sweeter flavor. Cool autumn days and chilly nights encourage slow, steady growth and improve quality.

The secret to a successful fall broccoli crop is planting at the right soil temperature—not simply by the calendar. Soil temperature determines how quickly seeds germinate, how vigorously young plants establish, and whether they mature before hard freezes arrive. This guide will show you when to plant, how to grow healthy plants, and how to harvest delicious broccoli from fall through early winter.

Best Soil Temperature for Planting

Broccoli grows best when seeds germinate in warm soil but mature in cool weather.

Ideal soil temperature for germination: 65–80°F (18–27°C)
Minimum soil temperature: about 45°F
Maximum practical soil temperature: about 85°F
Expected germination: 5–10 days under ideal conditions

Late summer soil is usually warm enough for rapid germination. During periods of extreme heat, keep the seedbed evenly moist and provide light afternoon shade for young seedlings if temperatures exceed 90°F.

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Projected harvest temperatures

Broccoli develops the best heads when daytime temperatures range between 60° and 70°F (16–21°C) with nighttime temperatures between 40° and 55°F (4–13°C).

Light frosts improve flavor, but prolonged temperatures below 25°F may damage mature heads.

When to Plant Fall Broccoli

For a fall harvest, sow seed or transplant 10 to 14 weeks before your average first fall frost, depending on the variety.

Typical planting times include:

Northern gardens: late June through July
Mid-latitude gardens: July through early August
Mild winter climates: August through September

Many gardeners start seeds indoors or in a shaded nursery bed during summer and transplant sturdy seedlings into the garden four to six weeks later.

Choose the Right Variety

Early and mid-season broccoli varieties are excellent choices for fall production.

Reliable varieties include:

Green Magic
Belstar
Packman
Marathon
Gypsy
Imperial
Arcadia
Waltham 29
Emerald Crown

Choose varieties whose days to maturity fit comfortably within your growing season.

Prepare the Soil

Broccoli is a heavy feeder and thrives in fertile, well-drained soil.

Before planting:

Loosen soil 10 to 12 inches deep.
Mix in several inches of finished compost.
Remove weeds and large stones.
Maintain a soil pH between 6.0 and 7.0.
Work in a balanced organic fertilizer before planting if needed.

Rich soil encourages vigorous growth and large heads.

Planting

Sow seeds:

½ inch deep
2 inches apart

Transplant seedlings when they have four to six true leaves.

Space plants:

18 inches apart
Rows 24 to 36 inches apart

Water immediately after transplanting to reduce transplant shock.

Water Consistently

Broccoli requires steady moisture throughout the growing season.

Provide approximately 1 to 1½ inches of water each week, increasing irrigation during periods of hot weather before autumn cooling begins.

Uneven watering can result in small heads or premature flowering.

Mulch around plants to conserve moisture and moderate soil temperatures.

Fertilizing

Broccoli benefits from regular feeding.

Apply a nitrogen-rich organic fertilizer about three weeks after transplanting to encourage vigorous leaf growth before heads begin forming.

Avoid excessive fertilization once heads develop.

Common Problems

Loose Heads

Usually caused by warm temperatures during head formation.

Buttoning

Small premature heads often result from:

Heat stress
Poor fertility
Stunted transplants

Yellow Flowers

Harvest immediately once buds begin loosening. Flowering reduces eating quality.

Cabbage Worms

Inspect plants regularly and remove caterpillars by hand or treat with Bacillus thuringiensis (Bt) when necessary.

Aphids

Strong sprays of water or insecticidal soap usually provide effective control.

Harvest

Most broccoli varieties mature 60 to 90 days after sowing or 50 to 70 days after transplanting.

Harvest when:

Heads are firm.
Flower buds remain tightly closed.
Heads reach full size for the variety.

Cut the main head with 6 inches of stem attached.

Many varieties produce smaller side shoots for several weeks after the main harvest.

Growing Tips

Grow broccoli for fall rather than spring whenever possible.
Keep plants growing steadily without drought stress.
Feed consistently early in the season.
Harvest before flower buds loosen.
Continue harvesting side shoots after the main head is removed.

My Experience Growing Fall Broccoli

I’ve grown broccoli in climates ranging from Iowa to coastal Massachusetts and now in Northern California, and my best crops have almost always been fall plantings. Summer warmth establishes vigorous plants, while cool autumn weather allows heads to develop slowly and densely without bolting. I rely on soil temperature rather than calendar dates to decide when to sow and transplant, and that approach has consistently produced larger, sweeter heads and longer harvests.

Frequently Asked Questions

Should I start broccoli indoors for fall?

Yes. Starting seed indoors or in a shaded nursery bed during midsummer often produces stronger transplants than direct sowing during hot weather.

What soil temperature is best for planting broccoli?

Seeds germinate best when soil temperatures range from 65° to 80°F.

Does broccoli tolerate frost?

Yes. Mature plants tolerate light frosts, which often improve flavor.

Why did my broccoli produce tiny heads?

Heat stress, poor fertility, transplant shock, or delayed planting commonly cause small heads.

Will broccoli grow side shoots after harvest?

Yes. Most varieties produce numerous smaller side shoots after the central head is harvested.

How often should broccoli be watered?

Provide about 1 to 1½ inches of water each week, adjusting for rainfall and hot weather.

Can broccoli be planted in containers?

Yes. Choose containers at least 12 inches deep and wide with fertile, consistently moist soil.

How long can broccoli remain in the garden after maturity?

Harvest as soon as heads reach full size while buds remain tight. Delaying harvest allows buds to open into yellow flowers.

Fall Garden Planting Calendar

Stage	Best Conditions
Ideal soil temperature for sowing	65–80°F (18–27°C)
Planting window	10–14 weeks before your average first fall frost
Transplant timing	Set out seedlings when they have 4–6 true leaves, about 4–6 weeks after sowing
Days to maturity	60–90 days from sowing (50–70 days from transplanting)
Best harvest temperatures	Days: 60–70°F (16–21°C) • Nights: 40–55°F (4–13°C)
Frost tolerance	Light frosts improve flavor; mature plants tolerate temperatures into the upper 20s°F

Tip: Broccoli grows fastest when the soil is warm, but it develops its largest, sweetest heads when autumn air temperatures turn cool. Plant while the soil is still warm enough for rapid establishment so your crop matures during fall’s ideal growing weather.

The Soil Temperature Takeaway

After decades of growing broccoli in climates from Iowa to Northern California, I’ve found that timing matters more than almost any other factor. Warm late-summer soil encourages rapid germination, vigorous root growth, and strong leafy plants. As autumn arrives and daytime temperatures settle into the 60s, broccoli shifts its energy into producing large, tight heads with excellent flavor. Rather than planting by the calendar alone, use soil temperature to know when to plant and air temperature to know when your broccoli will produce its highest-quality harvest.

Continue Growing Your Fall Garden

This article is part of the Harvest to Table Fall Planting Through Harvest Series, a collection of crop-by-crop guides that show you the best soil temperature for planting, the ideal planting window by climate, and the temperatures that produce the highest-quality harvests. If you’re planning an entire fall vegetable garden, start with The Complete Guide to Fall Vegetable Gardening: Planning, Planting, Growing, and Harvesting, then explore the crop guides below for detailed planting and growing advice.

Browse the Series

🥬 Leafy Greens