How to grow broccoli from transplant to side shoots

Broccoli is a cool-season crop that pays you back for a little planning. Get it in early, feed it well, and harvest on time. Do that, and one plant gives you a main head plus weeks of smaller side shoots.

When to plant broccoli

Broccoli forms its best heads in cool weather. Hot weather makes the heads loose and bitter, and the buds open into yellow flowers fast. Plan your planting so heads form before summer heat, or after it.

You can grow two crops a year.

Spring crop

Start seeds indoors 6 to 8 weeks before your last spring frost. Harden the seedlings off, then plant them out 2 to 3 weeks before your last frost date. Young broccoli handles light frost. My post on how to plant broccoli seeds covers seed starting in detail.

Cover young plants if a hard freeze is on the way. Here is what temperature to cover plants for frost.

Fall crop

Fall broccoli often tastes sweeter, and the heads hold longer in cool weather. To time it, count back from your first fall frost date. Use the days to maturity on the seed packet, then add about 2 weeks, since plants grow slower as the days get shorter. That puts most planting in mid to late summer.

Where to plant broccoli

• Full sun, at least 6 hours a day
• Rich, well-drained soil with lots of compost
• A soil pH of 6.0 to 7.0
• A bed that did not grow cabbage-family crops last year

Rotating beds each year helps prevent clubroot and cuts down on pests. Cabbage-family crops include broccoli, cabbage, kale, cauliflower, and Brussels sprouts.

How to plant broccoli transplants

1. Work 2 inches (5 cm) of compost into the bed.
2. Space plants 18 inches (45 cm) apart, in rows 24 to 36 inches (60 to 90 cm) apart.
3. Set each transplant a little deeper than it sat in its pot, up to the first set of leaves.
4. Water well.
5. Cover the bed with row cover right away to keep out cabbage butterflies and flea beetles.

Plant transplants while they are young and growing well. Older transplants that are root-bound in their pots often form tiny early heads instead of full-size ones.

Water and feeding

Broccoli is a heavy feeder. Give it 1 to 1.5 inches (2.5 to 4 cm) of water a week. Mulch keeps the soil cool and moist.

About 3 weeks after transplanting, side-dress with compost or a nitrogen-rich fertilizer like fish emulsion or blood meal. Feed again when the heads start to form.

How to harvest broccoli

Most varieties are ready 55 to 80 days after transplanting. Watch the head, not the calendar.

Cut the main head when:

• The buds are tight and dark green or blue-green.
• The head feels firm.
• No yellow petals show.

Use a sharp knife. Cut the stem 5 to 6 inches (13 to 15 cm) below the head, at a slant so water runs off the stump.

Do not wait for the head to reach grocery store size. Home-grown heads are often smaller. Once you see a hint of yellow, cut it that day.

Side shoots

Leave the plant in the ground after you cut the main head. Smaller side shoots grow where the leaves meet the stem. They are about 1 to 3 inches (2.5 to 8 cm) across. Pick them every few days and more will form. Plants can keep producing for several weeks, and longer in cool weather.

Check for hidden worms

Cabbage worms hide in the head and match its color. Soak the heads in cool salted water for about 15 minutes before cooking. The worms float out.

Common broccoli problems

Problem	Cause	Fix
Tiny heads early (buttoning)	Stress from cold snaps, drought, or root-bound transplants	Plant young transplants and keep them watered
Loose, open heads	Heat	Plant earlier in spring or grow a fall crop
Hollow stems	Fast growth or low boron	Feed in balance and add compost
Holes in leaves and green caterpillars	Imported cabbageworm	Use row cover, hand-pick, or spray Bt
Tiny round holes in leaves	Flea beetles	Use row cover
Gray clusters under leaves	Cabbage aphids	Spray them off with water

Bt (Bacillus thuringiensis var. kurstaki) is a natural bacterium that affects caterpillars only. It does not harm bees, ladybugs, or people. Keep it away from plants where you want butterfly caterpillars, like dill and parsley.

For more on aphids, see my post on aphids on plants.

Best broccoli varieties

Variety	Type	Notes
‘De Cicco’	Heirloom	Early, with a small main head and lots of side shoots
‘Calabrese’	Heirloom	Classic Italian type with good side shoots
‘Waltham 29’	Open-pollinated	Cold tolerant and good for fall
‘Green Magic’	Hybrid	Handles heat better than most

Start your seeds strong

Strong transplants make strong plants. These posts help:

• Seed starting guide
• Best grow lights for seedlings

If broccoli does well for you, try its cousins next: kale and cabbage. For another cool-season crop that shares the same timing, see how to grow spinach.