Broccoli

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Botanical name: Brassica oleracea

Plant type: Vegetable

USDA Hardiness Zones: 3, 4, 5, 6, 7, 8, 9, 10

Sun exposure: Full Sun

Soil type: Sandy

Soil pH: Slightly Acidic to Neutral

Broccoli is a cool-season crop that, like spinach, can be grown in the spring or fall. In fact, you may be able to get a continual harvest throughout both seasons if you time planting correctly. A member of the cabbage family, broccoli is rich in vitamins.

Planting

  • Broccoli is hardy; it can germinate at temps as low as 40ºF.
  • Broccoli requires full sun and moist, fertile soil that's slightly acidic.
  • If you live in a warm climate, a fall planting is best, as broccoli thrives in cool weather. Plant seeds in mid- to late-summer in most places.
  • For spring plantings, direct sow outdoors (or transplant seedlings) 2 to 3 weeks before last spring frost date.
  • For fall plantings, direct sow seeds outdoors 85 to 100 days before your average first fall frost.
  • If you transplant, assume 10 less days for growth or the "days to maturity" on the seed packet.
  • Work in 2 to 4 inches of rich compost or a thin layer of manure before planting.
  • Space plants 12 to 24 inches apart, depending on the side heads you want to harvest.
  • Plant seeds 1 inch deep, 3 inches apart. You will need to thin seedlings.

Care

  • Fertilize three weeks after transplanting.
  • Provide consistent soil moisture with regular watering, especially in drought conditions. Some varieties of broccoli are heat tolerant, but all need moisture.
  • Do not get developing heads wet when watering.
  • Roots are very shallow, do not cultivate. Suffocate weeds with mulch.
  • Mulch will also help to keep soil temperatures down.

Pests

  • Flea Beetles
  • Aphids: Curling leaves may mean that the plant's sap is being sucked by insects. Apply soapy water to all sides of leaves whenever you see aphids.
  • Downy mildew: Yellow patches on leaves are usually caused by moist weather. Keep leaves as dry as possible with good air circulation. Buy resistant varieties.
  • Cabbage loopers: Small holes on the leaves between the veins mean small green caterpillars are present. Look at the undersides of the leaves. Hand pick if the problem is small or control with Bacillus thuringiensis. Use a floating row cover just after planting through harvest to prevent caterpillars.
  • Cabbageworms and other worm pests: Treat same as loopers.
  • Whiteflies
  • Nitrogen deficiency: If the bottom leaves turn yellow and the problem continues toward the top of the plant, the plants need a high nitrogen (but low phosphorus) fertilizer or bloodmeal. Apply at planting, after the main head emerges, and after the main head is harvested. 
  • Clubroot: Quickly wilting plants may be due to this fungus in the soil.  The entire plant, including all roots and root tendrils, must be gently dug up and removed. If the roots are gnarled and misshapen, then clubroot is the problem. Act quickly to remove the plants so that the fungus doesn't continue to live in the soil. Do not compost the plants. Raise the pH of your soil to above 7.2. You may need to sterilize your soil, too.

Harvest/Storage

  • In terms of timing: Harvest broccoli when the buds of the head are firm and tight before the heads flower. If you do see yellow petals, harvest immediately.
  • For best taste, harvest in the morning before the soil heats up.
  • Cut heads from the plant. taking at least 6 inches of stem.
  • Cut the stalk of the main head at a slant, about 5 to 8 inches below the head.
  • Most varieties have side-shoots that will continue to develop after the main head is harvested. You can harvest from one plant for many weeks, in some cases, from spring to fall, if you’re summer isn’t too hot.
  • Store broccoli in the refrigerator for up to 5 days. If you wash before storing, make sure to dry it thoroughly.
  • Broccoli can be blanched and frozen for up to one year.

Recommended Varieties

  • ‘Green Goliath’ is heat-tolerant and sprouts side shoots that will mature for harvesting.
  • ‘Green Duke’ is heat tolerant and an early variety that's especially good for Southern gardeners.
  • ‘Calabrese’ is a prolific Italian heirloom that sprouts side shoots that will mature for harvesting. Great for fall planting, too.
  • 'Flash' is a fast-growing heat-resistant hybrid with good side-shoot production once the central head is cut. Great for fall planting, too.
  • ‘Paragon’ is a popular variety in Canada.

Recipes

Wit & Wisdom

One ounce of broccoli has an equal amount of calcium as one ounce of milk.

Comments

By Almanac Staff

Click on the yellow "Gardening" tab to the left and you'll see planting links.

By Anonymous

How do I harvest seeds from my Broccoli plant? Ive let one plant flower but not sure when or how to harvest seeds.

By Almanac Staff

Broccoli isn't the best veggie for seed-saving but you can do it. First, note that you can't have any other crops from the Brassica oleracea family within a mile or they'll cross-pollinate and it won't be pure broccoli. Also, you want to seed save from heirloom veggies versus hybrids. Do not harvest heads on broccoli plants that you wish to save for seed. Carefully dig the plants and pot them in sand. Store plants between 32-40° F. Plant back out in early spring and allow to bolt. Harvest seed pods when dry and clean by hand. See more on Seed Saving: http://www.almanac.com/content/quick-seed-saving-guide-beginners

By Anonymous

I've harvested the main head and some of the side heads have gone to seed. Should I pull up the plant now and plant something else? How do I know when to pull up a plant after it's done.

By Almanac Staff

Yep, it's done. Pull out the broccoli plant. It's gone to seed and will only start to taste bitter. Now you can sow a plant that fits the middle of summer in your area!

By Anonymous

In the Northeast climate, can you use floating row covers during July and August?

By Almanac Staff

Yes. Floating row covers is an excellent way to prevent pests. Apply just after planting. You can keep over broccoli for the life of the plant since they do not require insects to pollinate them. However, it is important to secure the edges of the cover tightly (with landscaping pins).

By Anonymous

Its been 30 days all I have are big big leaves. Is that okay

By Almanac Staff

Keep on watering and your broccoli should soon sprout!

Thank you for your interest in the Old Farmer's Almanac and our Web site.

By Anonymous

I planted broccoli plants from a nursery about 6 weeks ago. Broccoli heads are growing nicely but I have tall stalks with flowers too. Should I cut those off? They are now so tall they are leaning over.

By Almanac Staff

It seems as though your plant has gone to seed! Pick them off and hopefully smaller florets will grow in their place.

Thank you for your interest in the Old Farmer's Almanac and our Web site.

By Anonymous

when do you know it's time to pull out the plant after harvesting the florets?

By Almanac Staff

Harvest while buds are starting to swell (match-like size) or if it begins to loosen from the plant itself. If you wait to long, they'll flower.

Thank you for your interest in the Old Farmer's Almanac and our Web site.

By Anonymous

when YOU CUT THE HEAD TO EAT, WILL ANOTHER HEAD GROW THERE , or will it be just side shoots from there ?

By Almanac Staff

It won't grow the same central head, but it will grow more, smaller heads to enjoy.

By Anonymous

I planted my seedlings about a week and a half ago. For some reason, there is already a broccoli on some of them. It is small and the plant itself is only about 12 inches high. Can I clip this little broccoli and more will grow later, or is it a goner?

By Almanac Staff

It's hard to say without a photo link, but does the broccoli head look like a small "button"? There are several possibilities for this: 1) Plants that remain too long in seed flats or have outgrown their container may produce "button" heads soon after planting. 2) Plants that have experienced a rapid change in temperature such as warm to cold nights without any "hardening off" and transition may button. 2) Dry spells, cold nights, or really erratic weather can affect the early broccoli growth.
If you have this issue with the main head, your broccoli can still produce great side shoots after the main head is cut.

By Anonymous

It didn't look like a button. It looked like a side shoot would look like towards the end of the season. It was tall, but small and coming out of the middle. I took it off, hoping to get the plant to produce another one. We have had weird weather her in Maine. Very hot in March and April for a week or so but now we have has lower than normal temps in the 40's and 50's. I have more broccoli and caulif. growing for the fall in the house, so if these are a loss I do still have more coming.

By Almanac Staff

It sounds like the plants are healthy. I think they will grow more broccoli flowers.

By Anonymous

I did not harvest my broccoli before the yellow flowers grew. Will the plant still grow after I cut them off?

By Almanac Staff

Your plant has gone to seed, however, you can cut off the head and let the plant develop new baby/side heads for eating!

By Anonymous

Does this mean you can not eat the broccoli? My first head started flowering, what should I do with the head?

By Catherine Boeckmann

If you do see yellow petals growing the green head of broccoli, harvest immediately.
To harvest, cut the stem below the head, taking at least 6 inches.

By cynde129

My plants are turning white and drying up, What is the problem? We have had 85-92 degrees lately. I have been watering them also.Thanks for any help.

By Almanac Staff

It might be nitrogen deficiency--one of the more common problems as broccoli is a heavy nitrogen feeder, Apply blood meal or a high nitrogen (but low phosphorus) fertilizer at planting and also when the main head emerges and after the main head is harvested. Also: During the growing period, the temperature should be between 40 degrees and 70 degrees.

By Anonymous

Have very young small stem planets that looked like they were heading up but..alas..it turned into a yellow flower..what going on..what can I do.

By Almanac Staff

If you have premature flowering, this is usually due to very warm temperatures at heading time. Broccoli is a cool-weather plant.

By Anonymous

How long does it usually take for broccoli and brussel sprouts to get ready to harvest? I'm using plants and not seeds.

By Almanac Staff

It depends on the variety, season, and fertilization but usually the head is as large as it's going to get when the individual buds of the broccoli are match-head size.

By Almanac Staff

Broccoli seedlings will take 8 to 12 weeks from transplant until harvest time, depending on the variety. But look for the cues mentioned above! You really only have 1 week or so to do the first harvest. If you leave it too late, yellow flowers will form.

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