How to Grow Broccoli:
From Seed to Harvest

Broccoli at a Glance

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Types of Broccoli

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Best Broccoli Varieties

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When to Plant Broccoli

Broccoli must mature in cool weather. Heads that form in summer heat are small, loose, and quick to open into yellow flowers. Timing is the first step in how to grow broccoli well.

• Spring: Start seeds indoors 4 to 6 weeks before your last frost, and set plants out 2 to 4 weeks before the last frost, after hardening them off. Time it so heads form before temperatures stay above 80°F.
• Fall (the best crop): Start seeds indoors 10 to 12 weeks before your first fall frost, and set plants out 8 to 10 weeks before it. Or sow seeds right in the garden about 90 days before first frost.
• Mild winters: Where winters stay above about 20°F, plant in fall for a harvest the next spring.
• Stagger plantings: Set out a few plants every couple of weeks so they don't all ripen at once.

See our vegetable planting calendar for more.

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Starting Broccoli Seeds Indoors

Sow seeds 1/4 to 1/2 inch deep, two per cell, in seed-starting mix. They sprout in 5 to 10 days at 65 to 75°F. Give them strong light right away, 14 to 16 hours a day under grow lights or in your sunniest window, so they don't get leggy. Starting your own seedlings is the usual first step when you learn how to grow broccoli.

Thin to one plant per cell, and harden off for 7 to 10 days before planting out. Leggy seedlings can be planted deeper, up to the first true leaves. See growing vegetables from seed.

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Soil, Spacing, and Planting

Broccoli is a heavy feeder. Work 2 to 3 inches of compost plus a balanced organic fertilizer into the bed. Hungry plants make small, loose heads. Rich soil is half the secret of how to grow broccoli with big, tight heads.

Aim for a pH of 6.0 to 7.0. If your soil is acid, add lime; it also helps prevent clubroot, a serious cabbage-family disease.

Space plants 12 to 18 inches apart in rows 24 to 36 inches apart (one per square foot in a square foot garden). Wider spacing gives bigger main heads.

Rotate: don't plant broccoli or any cabbage-family crop (cabbage, kale, cauliflower, Brussels sprouts) in the same spot for 3 to 4 years.

Cutworm collars: wrap a strip of cardboard around each stem at planting, an inch below and above the soil, to protect young plants.

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Watering and Feeding Broccoli

• Water: 1 to 1 1/2 inches a week, especially while heads form. Dry spells give small, loose heads. Water at the base, not over the heads.
• Mulch: 2 inches of straw or shredded leaves keeps the soil moist and cool.
• Feed: Side-dress with compost or balanced organic fertilizer 3 to 4 weeks after planting, and again with compost when the head is about an inch across.
• Yellow lower leaves: usually mean the plant needs nitrogen. Feed with fish emulsion or blood meal.

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How to Harvest Broccoli

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Cut the main head while the buds are tight and dark green, usually 4 to 8 inches across, before any yellow flowers show. Check every two or three days; in warm weather a head can go past its best quickly. Knowing when to cut is the last part of how to grow broccoli well.

Leave the plant in the ground. Cut the head with a sharp knife, leaving 4 to 6 inches of stem. Most varieties then grow side shoots, small heads 1 to 3 inches across, for another 4 to 6 weeks. Keep picking them before they flower.

Too much to eat? Blanch and freeze it. See freezing broccoli.

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How to Grow Broccoli as a Fall Crop

Fall broccoli is the finest of the year in most climates. Heads that ripen in cooling weather are denser and sweeter, and a light frost makes them even sweeter. If you only learn how to grow broccoli one way, make it a fall crop.

The hard part is getting started in midsummer heat. Water young transplants often, shade them with shade cloth during hot spells, and choose heat-tolerant varieties. Once the weather cools in September, they grow fast. See our fall vegetable garden guide.

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Broccoli Problems and Solutions

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Companion Planting for Broccoli

• Good companions: Celery and dill (help against cabbage white butterflies), nasturtiums (draw aphids away), marigolds, onions, garlic, chives, rosemary, and beans or peas nearby.
• Keep apart: Tomatoes, peppers, strawberries, and fennel.

See our companion planting chart.

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Broccoli Questions

How long does broccoli take to grow?

50 to 80 days from transplant to the main head, plus 5 to 6 weeks of seed starting indoors. Fall broccoli is usually ready 10 to 14 weeks after setting out.

Why is my broccoli head so small?

Usually stressed transplants, heading in hot weather, low nitrogen, or crowding. Fall broccoli in rich, well-spaced soil makes the biggest heads.

Can I grow broccoli in a container?

Yes. Use at least a 5-gallon pot per plant (10 gallons is better), water often, and feed weekly. Belstar does well in pots.

What do I do after cutting the main head?

Leave the plant growing. It will make side shoots for 4 to 6 weeks; keep picking them before they flower.

Is spring or fall better for broccoli?

Fall, in most areas. Heads ripen in cooling weather and come out denser and sweeter.

Source: NC State Extension.

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More Vegetable Growing Guides

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