Plot · field guide
How to Grow Broccoli
Broccoli is a cool-season crop, which is the whole secret to growing it. Plant it in the heat of summer and it bolts to flower before it makes a head. Time it for the cool ends of the year, spring and fall, and one plant gives you a main head plus weeks of side shoots. Here is how to do it.
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Time it for cool weather
Broccoli forms tight heads only while the weather stays cool, roughly 60 to 70 degrees Fahrenheit. That gives you two windows a year: an early spring crop and a fall crop. Of the two, fall is easier, because the weather is cooling into the harvest instead of heating up toward a bolt.
From a transplant, broccoli takes about 60 days to a head, versus about 70 days from seed. For spring, count back from your last frost and start early. For fall, count back about 60 days from your first fall frost and set transplants out in late summer.
- Broccoli heads up best at 60 to 70 degrees Fahrenheit.
- Grow it in spring and fall; fall is the easier crop.
- About 60 days to a head from a transplant, 70 from seed.
Start with transplants and space them wide
Transplants beat direct seed for broccoli because they let you hit the cool window on time. Buy young plants or start seed indoors about 5 weeks before you want to set them out.
Give each plant real room: space them 18 inches apart in the row, with 30 inches between rows. Broccoli is a big, leafy plant, and crowding it makes small heads and traps damp air that invites disease. Full sun, 6 hours or more, keeps the heads tight.
- Use transplants; start seed indoors about 5 weeks ahead.
- Space plants 18 inches apart, rows 30 inches apart.
- Give it full sun, 6 hours or more, for tight heads.
Beat the cabbage worms
The main pest is the cabbage worm, the small green caterpillar that hatches from those little white moths you see fluttering over the garden. They chew ragged holes in the leaves and hide down in the head, and a bad run can strip a plant fast.
The cleanest fix is Bt, a natural spray that only harms caterpillars and is safe for bees and people. Spray the leaves every 7 to 10 days once you see the white moths, and hit the leaf undersides where the worms feed. A row cover over young plants keeps the moths from ever laying eggs.
- Cabbage worms are the main pest; watch for small white moths.
- Spray Bt every 7 to 10 days, including the leaf undersides.
- A row cover on young plants blocks the moths from laying eggs.
Cut the center head, then keep picking
Harvest the main head while the buds are still tight and green. Once those buds swell and start to show yellow, the head is opening into flowers and the quality drops fast. Cut the center head with about 6 inches of stem, on a cool morning.
Do not pull the plant. After you cut the center head, most broccoli sends up smaller side shoots from the leaf joints, and those keep coming for another 3 weeks or so. They are small, but a steady stream of them adds up to real food from one plant.
- Cut the main head while the buds are tight and green.
- Harvest before the buds yellow and open into flowers.
- Leave the plant in; side shoots keep coming for about 3 weeks.
Questions, answered straight
In the cool ends of the year, spring and fall, because broccoli heads up best at 60 to 70 degrees Fahrenheit and bolts in summer heat. Fall is the easier crop. Count back about 60 days from your first fall frost to set out transplants.
About 60 days to a head from a transplant, or about 70 days from seed. After you cut the main head, side shoots keep producing for roughly another 3 weeks.
Almost always cabbage worms, the green caterpillars from small white moths. Spray Bt every 7 to 10 days, hitting the leaf undersides, or cover young plants with a row cover so the moths cannot lay eggs.
The main head does not regrow, but the plant does. After you cut the center head, most broccoli pushes out smaller side shoots from the leaf joints for about 3 more weeks, so leave the plant in the ground and keep picking.