How to Grow Broccoli

Updated August 2026 · Garden Advice Guide

Broccoli is a cool-season crop that has to reach full size and form its head before real heat arrives, which means the whole job is counting backward from your weather and starting on time. Give it rich soil, 18 inches of space per plant, steady water, and a nitrogen feed every 3 weeks, and it will make a tight head in 60 to 100 days from transplant. The two failures that ruin a crop are buttoning, where a stressed young plant makes a tiny premature head, and bolting, where a mature plant flowers into yellow before you cut it.

Both are timing problems, not care problems. Fix the calendar and broccoli is easy.

Not sure when to start? Get your sowing and transplant dates with our free When-to-Plant tool.

Buttoning: The Failure Nobody Warns Beginners About

A buttoned plant makes a head the size of a quarter, on a plant a foot tall, weeks before it should. It looks like the plant is early. It isn't. It's finished.

Broccoli decides to form a head based on stem thickness and cold exposure. A young plant that gets checked hard enough to stop growing, then gets a cold signal, concludes it's a mature plant heading into a season change and does what mature plants do. It flowers. Once the head is initiated, the plant cannot go back to making leaves and start over, and it will not size that head up. A buttoned plant is a compost plant.

What causes it:

• Transplant stress. Root-bound seedlings held too long in small cells are the number one cause. A 6-week-old plant that has circled its roots in a 1-inch cell has already been stressed for two weeks before it hits the garden.
• Transplanting too early into cold soil. A stem thicker than a pencil exposed to sustained temperatures below 50F, or a hard snap under about 40F, reads as vernalization.
• Drought at transplant. A seedling that wilts hard in its first week gets the same growth check.
• Starving in the cell. Seedlings held in plug trays without feeding turn purple and stall, which is a growth check by another name.
• Setting out plants that are too old. Over about 6 weeks in a cell, risk climbs steeply.

What prevents it:

1. Transplant at 4 to 6 weeks, with 4 to 5 true leaves, and not later. Age matters more than size.
2. Pot up rather than hold. If weather delays you, move seedlings into 3 inch or 4 inch pots so roots keep running.
3. Feed seedlings with a half-strength liquid feed weekly from the second true leaf.
4. Harden off gradually over 7 to 10 days rather than dumping plants into wind and cold. Our guide to hardening off seedlings has the schedule.
5. Wait for soil above 50F for spring transplants, or protect with row cover for the first two weeks.
6. Water in thoroughly at planting and keep the root zone moist for the first 10 days.

Buttoning is why fall broccoli is more forgiving. Fall transplants go into warm soil and grow without a check, so the cold signal never lands on a young plant.

How to Grow Broccoli in Spring Versus Fall

There are two windows, and deciding when to plant broccoli is the choice that determines everything else. Both crops work. Fall is easier in most of the country, and it produces better heads.

Spring broccoli is a race. You transplant into cool weather, the plant grows toward summer, and the head has to be cut before sustained heat above about 80F pushes it to open into yellow flowers. Miss by ten days and you get a loose, ricey head that tastes sharp.

Fall broccoli grows into cooling weather. Heads size up slowly in the exact conditions broccoli likes, they hold on the plant for weeks instead of days, and a light frost sweetens them because the plant converts starch to sugar. Established plants take 26 to 28F without damage, and heads themselves survive light frost.

The arithmetic behind the fall column: count back from your first fall frost by the variety's days to maturity, then add 14 days, because plants grow measurably slower as daylight shortens. A 65-day variety in a zone 6 garden with an October 20 frost means transplanting around July 25, not August 10.

Treat these as regional averages. Zone maps and frost tables come from 30-year station averages spread over a wide area, and elevation, slope, and nearby water move your real dates by a week or two in either direction. Check your own numbers with the frost dates tool and confirm your zone with the growing zones lookup.

Broccoli is nearly always transplanted rather than direct sown, because the spring window is too short to spend 3 weeks on germination in the bed. For fall, direct sowing works well in zones 5 and warmer if you can keep the seedbed damp. Our seed starting guide covers the indoor side.

Spacing: Why Crowded Broccoli Makes Small Heads

Head size tracks plant size almost exactly, and plant size tracks how much light, water, and root room each plant gets. Crowding is the most common reason a well-cared-for bed produces heads the size of a golf ball.

Eighteen inches is the honest minimum for a full-size head. Gardeners squeeze broccoli to 12 inches all the time and then wonder why the heads are small. The plant is telling you exactly what it got.

Broccoli also needs airflow. Crowded plants stay damp in the leaf axils, which is where aphid colonies build and where downy mildew starts.

Work out plant counts for your actual bed with the plant spacing calculator rather than eyeballing it. A 4x8 raised bed at 18 inches holds 8 plants, not the 15 most people try to fit.

Feeding and Watering a Heavy Feeder

Broccoli is one of the hungriest vegetables in the garden, and it will not make a large head on thin soil no matter how long you wait.

Soil prep before planting:

• Work in 3 to 4 inches of finished compost across the bed, not just in the planting hole. Our composting guide covers making enough of it.
• Target pH 6.0 to 7.0. Slightly above 6.8 also suppresses clubroot, which is worth knowing if your area has it.
• Add a balanced granular fertilizer at planting, following the label rate for your product.

Feeding schedule after transplant:

The leaf count matters. Broccoli builds its head from the energy stored in the leaves it made first, and a plant with 15 to 20 large healthy leaves at heading makes a big head. A plant with 8 small ones cannot, whatever you feed it at that point. Front-load the nitrogen.

Water: 1 to 1.5 inches per week, delivered evenly. Broccoli roots run 18 to 24 inches deep, so deep and regular beats light and daily. What you're avoiding is the dry-then-flood cycle, which causes hollow stem and uneven, bumpy heads. Mulch 2 to 3 inches of straw once the soil warms, which also keeps root-zone temperatures down and buys the spring crop an extra week. Our watering guide converts inches per week into run time for your setup.

Harvesting the Main Head at the Right Moment

Cut while the beads are tight and dark green. That's the entire signal, and it's a narrow window, sometimes 3 or 4 days in warm weather.

Signs it's ready:

• The head is firm and dome shaped, with beads packed tightly together.
• Color is deep green, or purple on purple varieties.
• Size has stalled for a day or two. Head size depends more on variety and spacing than on waiting.

Signs you waited too long:

• Beads loosen and the head looks grainy or open.
• Yellow shows anywhere in the head. Yellow is an opening flower, and the flavor turns sharp within a day.
• The head feels soft rather than firm.

How to cut: take the stalk 5 to 6 inches below the head with a sharp knife, at a slant so water runs off the cut rather than pooling and rotting the stem. Cut in the morning while the head is cool and full of water.

If a heat wave is forecast and the head is nearly there, cut it early. A slightly small tight head is a good vegetable. An open yellow head is not. Our when to harvest tool lists broccoli maturity windows alongside the rest of the garden.

Side Shoots: The Second Harvest Most Beginners Miss

Cutting the main head does not end the plant. Leave it in the ground, keep feeding and watering it, and broccoli pushes small heads from the leaf axils all down the stem for another 4 to 8 weeks. Most home gardeners pull the plant after the main cut and throw away half the crop.

How it works:

1. Cut the main head 5 to 6 inches down the stalk, leaving all the leaves and the lower stem intact. The buds you want are sitting in those leaf joints.
2. Feed within a few days with a nitrogen-forward liquid feed and keep water steady. The plant is being asked to grow again.
3. Side shoots appear in 1 to 2 weeks, ranging from 1 to 3 inches across.
4. Pick them small and often, every 3 to 5 days. They open into flower faster than the main head does.
5. Keep going until the plant quits, which is usually 4 to 6 weeks in spring and up to 10 weeks on a fall crop under cooling weather.

Total side shoot yield from a well-fed plant often matches the main head by weight, and the shoots are more tender. On a fall crop in zone 7 or warmer, plants frequently produce into December.

Sprouting types make this their whole purpose. De Cicco, Calabrese, and purple sprouting broccoli produce a small main head and then heavy shoots. If side shoots are what you want, grow one of those rather than a big-headed hybrid, which tends to give one large head and little afterward.

Broccoli Varieties Compared

For a spring crop, choose the shortest days to maturity you can find with good heat tolerance, because you're racing the season. Green Magic and Packman are the standard picks.

For fall, use the longer, cold-loving types. Marathon and Waltham 29 make their best heads in weather that would already have bolted a spring variety.

Purple sprouting broccoli is a different animal. Sown in early summer, it grows all season, overwinters as a large plant in zones 6 and warmer, and delivers weeks of tender purple shoots in early spring when nothing else is producing. It takes a bed for nearly a year, which is the tradeoff.

Cabbage Worms, Aphids, and What to Do First

Two pests account for most broccoli complaints, and both respond best to prevention rather than treatment.

Cabbage worms are the velvety green caterpillars that chew ragged holes in leaves and hide in the head itself. The adults are the white butterflies you see flitting over the bed all summer, plus the gray-brown cabbage looper moth at night.

Order of control, cheapest and safest first:

1. Cultural. Rotate brassicas away from last year's bed. Clear crop residue promptly, since pupae overwinter in it. Time a fall crop so the heaviest butterfly flights are past.
2. Physical. Floating row cover from the day you transplant, sealed at the soil edge with boards or pins, is close to complete control and is the single most effective thing on this list. Brassicas need no insect pollination, so the cover can stay on all season. Hand picking works too, and a weekly two-minute check of leaf undersides catches eggs, which are small yellow rice grains laid singly.
3. Biological. Encourage parasitic wasps by letting a few dill, cilantro, or alyssum plants flower nearby. Bt, a naturally occurring soil bacterium, is a targeted biological option for caterpillars specifically, and it does not affect bees.
4. Chemical, last. If you get here, use a product whose active-ingredient class is specifically labeled for caterpillars on broccoli, follow the label's rate and pre-harvest interval exactly, and never treat a plant that has bolted into flower. The label is the law, and a product legal on one crop is illegal on another.

Aphids cluster in the growing tip and inside the head, which is what makes them so unwelcome, since a head packed with gray cabbage aphids is hard to wash out. Blast the tips with a strong jet of water twice a week from the moment you see the first colony, remove badly infested leaves, and avoid overfeeding nitrogen after heading, since soft lush growth is what they multiply on. Ladybug and hoverfly larvae will do most of the work if you leave them alone. Our full guide on how to get rid of aphids covers the sequence in detail.

Soaking heads before cooking: submerge in cold salted water for 20 minutes. Anything hiding inside floats out.

Other Common Broccoli Problems

Worked Example: A Zone 6 Fall Broccoli Crop

Take a garden with a first fall frost around October 20 and a 4x8 raised bed, 32 square feet.

Pick the variety. Marathon, 70 days from transplant.

Count back. October 20 minus 70 days is August 11. Add 14 days for slowing fall growth and you get a transplant date of July 28.

Count back again for seed. Broccoli takes 5 weeks from sowing to a transplant-ready seedling, so sow on June 23. Sow into 3 inch pots rather than small cells so the plants never get root bound.

Plant count. At 18 inches in row and 24 inches between rows, the 8-foot length holds 5 plants per row and the 4-foot width holds 2 rows, so 10 plants. That's realistic. Trying for 15 in the same bed is what produces 3-inch heads.

Feeding. Compost worked in before planting. Nitrogen side dressing on August 18 and again on September 8. Balanced feed when heads first show in late September.

Water. 1.25 inches per week over 32 square feet is about 25 gallons weekly, split into 2 deep waterings.

Harvest. Main heads cut around October 6 to October 14, at 5 to 7 inches. Side shoots from late October through the first week of December, since fall plants take frost and keep pushing. Total from 10 plants: roughly 12 pounds of main heads plus 8 to 10 pounds of side shoots.

Cover. A single layer of row cover from November 1 keeps the shoots coming through the mid-20s.

Run your own frost date through the when to plant tool and the same arithmetic gives you your dates.

FAQ

Why is my broccoli head so small?

Almost always crowding, thin soil, or too little sun. Broccoli builds its head from energy stored in the leaves it made first, so a plant with 15 to 20 big leaves makes a big head and one with 8 small leaves cannot. Space at 18 inches minimum, work in 3 to 4 inches of compost before planting, side dress with nitrogen at 3 and 6 weeks, and give it full sun.

What is buttoning in broccoli and can I fix it?

Buttoning is a tiny premature head, roughly the size of a quarter, formed on a young plant. It's caused by a growth check, usually root-bound seedlings, transplanting into cold soil, drought at planting, or unfed seedlings held too long. It cannot be reversed once the head is initiated, so pull the plant and change the seedling routine: transplant at 4 to 6 weeks, pot up if delayed, feed weekly, and wait for soil above 50F.

Should I grow broccoli in spring or fall?

Fall is easier and usually better in most zones. Spring broccoli races rising heat, and heads open into yellow flower if you miss the window by a week. Fall broccoli grows into cooling weather, heads hold on the plant far longer, and light frost sweetens them. Fall transplants also go into warm soil, so buttoning is much less likely.

Does broccoli grow back after you cut it?

The main head does not regrow, but the plant pushes side shoots from the leaf axils for another 4 to 8 weeks if you leave it in the ground. Cut the main head 5 to 6 inches down the stalk, keep all the leaves, feed with nitrogen right after, and pick the small shoots every 3 to 5 days. Sprouting types like De Cicco and Calabrese produce the heaviest shoots.

How far apart should broccoli plants be?

Eighteen inches between plants and 24 to 30 inches between rows for a full-size head. Twelve inches works only if you're happy with 3 to 4 inch heads. Wider spacing at 24 inches gives the largest heads and the best airflow, which also reduces aphids and downy mildew.

When do I know broccoli is ready to pick?

Cut when the head is firm, dome shaped, deep green, and the beads are packed tightly. The moment any yellow shows, the flowers are opening and flavor turns sharp within a day. In warm weather that window can be as short as 3 or 4 days, so check daily once the head reaches 4 inches, and cut early rather than late if heat is forecast.

How do I keep cabbage worms out of my broccoli?

Floating row cover from the day you transplant, sealed at the soil edge, is the most effective single step, and broccoli needs no insect pollination so the cover can stay on all season. Back it with a weekly check of leaf undersides for the small yellow eggs, hand picking, and letting dill or alyssum flower nearby to bring in parasitic wasps. Reach for a spray only if those fail, use a product labeled for caterpillars on broccoli, and follow the label exactly.

Can broccoli survive frost?

Yes. Established plants handle 26 to 28F without damage, and light frost improves the flavor by converting starch to sugar. Heads themselves tolerate a light frost, though a hard freeze below the mid-20s can damage an exposed open head, so drape a row cover over the bed on the coldest nights. This cold tolerance is exactly why fall broccoli keeps producing side shoots well past the first frost.

Updated August 2026