Common name: Broccoli, Italian broccoli, Calabrese, brocks.
Botanical name: Brassica oleracea italica
Broccoli is a hardy biennial grown as a cool-season annual. It grows 18 to 36 inches tall and has broad, thick leaves and a thick main stalk. Broccoli forms single or multiple flowers “heads ” of tiny blue-green flower buds. The flowers heads are eaten before they bloom; buds open to tiny yellow flowers. Broccoli will bolt and go to seed in warm temperatures or when daylight hours lengthen.
Broccoli is a cool-season crop yjerefore it is advisable that you grow broccoli so that it comes to harvest when temperatures average no more than75°F (23°C) each day.
Unlike its leafy cabbage cousins, broccoli is grown for its immature flower heads. The secret to growing broccoli is to encourage full, healthy flower heads but to harvest them before they mature (“bolt”) and lose flavor.
There are many varieties of broccoli to choose from, from the popular large-headed varieties to spicy broccoli Raab to Romanesco and sprouting varieties. Some types of broccoli focus on one main flower head, while others sprout smaller individual florets. Make sure you understand the growing habits of your variety of broccoli in order to harvest properly.
With broccoli, you may even be able to get a continual harvest throughout the summer and fall if you practice succession gardening and your summers don’t get excessively hot. A member of the cabbage family, broccoli is rich in vitamins.
You can plant a spring and early summer crop in late winter or early spring. Plant a fall or winter crop in mid to late or summer or early fall.
Broccoli is easier to grow from transplant seedlings. Whether they’ve been grown in your house or inside a greenhouse (find them at garden centers), broccoli seedlings need to be hardened off by gradually exposing them to longer periods of sunlight over several days.
Start by bringing the seedlings outside to a shady spot for 30 minutes, and slowly increase the amount of exposure outside over a week or two. Don’t immediately put them in direct sun or they’ll burn.
You can direct-sow seeds 1/2 inch deep into the ground as soon as you can work the soil and are sure the temperatures won’t be too cold for growing.
At planting time, add compost to the soil or scratch in a balanced fertilizer (such as 10-10-10) according to label directions.
Broccoli grows best in compost-rich, well-drained soil with a soil pH between 6.0 and 6.8. Broccoli grows best where air temperatures range between 45° and 75°F. Broccoli is frost hardy and can tolerate temperatures as low as 20°F.
In regions where there is heavy rain or sandy soil, aged-compost should be added to the soil to supplement soil nitrogen.
Space broccoli seedlings 18 to 24 inches apart. Place them in well-drained soil that receives at least eight hours of sun per day. If you live in a warm climate, consider spring-planting broccoli in partial shade to keep the broccoli from bolting, or going to seed when it gets warmer.
Broccoli plants need 1 to 1-1/2 inches of moisture each week. If you water, it’s better to water deeply less frequently. Light, frequent watering can lead to roots clustered near the soil’s surface, and broccoli’s root system is already very shallow. Too little water can result in tough stems.
A 1- to 3-inch layer of organic mulch around the plants helps conserve moisture and keep weeds at bay.
Try several types of broccoli, and make note of how they taste. Some people believe the flavor is sweetest in the fall after a light frost.
• Start broccoli seed indoors 5 to 6 weeks before the last frost in spring for spring planting.
• Start broccoli in the garden in mid to late summer to grow a late fall or early winter crop. In mild winter regions, plant in fall for winter harvest.
• Transplant broccoli seedlings to the garden when they are 4 to 6 weeks old, as early as the last frost in spring, after hardening off the seedlings for 4 days.
• In mild-winter regions, start seeds indoors in late summer and set them in the garden in autumn for winter harvest.
• Broccoli will come to harvest in 55 to 85 days when grown from transplants and 70 to 100 days when grown from seed.
Some varieties of Broccoli along with their time of maturity include:
Arcadia (63 days), Bonanza (55 days), Citation, DeCicco (48 days), Early Dividend, Emperor (80 days), Eureka (87 days), Green Comet (78 days), Green Goliath (75 days), Green Jewel, Green Valiant (70 days), Gypsy (58 days), Happy Rich (55 days), Italian Sprouting (80 days), Land Mark, Legend (86 days), Love Me Tender, Marathon, Minaret, Packman (80 days), Paragon (75 days), Pinnacle Premium Crop (58 days), Late Purple Sprouting (220 days), Raab Spring, Rapine (70 days), Romanesco (70 days), Saga (57 days), Salad, ShoGun (93 days), Small Miracle, Sprinter, Super Blend, Super Dome, Thompson, Violet Queen (70 days), Waltham (95 days).
- ‘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.
1. Broccoli Planting Time
Broccoli is a cool-weather crop that must come to harvest before temperatures rise consistently above 75°F. Start broccoli seed indoors 5 to 6 weeks before the last frost in spring. Transplant broccoli seedlings to the garden 2 to 3 weeks before the last frost in spring after hardening seedlings off for 4 days.
In mild-winter regions, start seeds indoors in late summer and set them in the garden in autumn for winter harvest. Weather that is too cold or too warm will cause broccoli to go to seed without forming a head. In cold-winter, short-season regions start broccoli in summer for fall harvest.
Broccoli Growing Tips
- Feeding: Broccoli grows in a hurry, and it needs a lot of nutrients. Rich compost will help feed your hungry broccoli, but it will also benefit from applications of compost tea or from monthly applications of a balanced organic fertilizer.
- Watering: Like other veggies, broccoli needs to be kept evenly moist. Give broccoli about an inch of water per week, and water deeply (rather than sprinkling) to encourage deep roots, but don’t let your broccoli plants become too dry between waterings.
- Diseases & Pests: Broccoli isn’t plagued by many diseases. The most common insect pests are aphids, cabbage worms, and slugs.
- Bolting: When growing broccoli in the spring, you’re in a race with the weather to keep your plants from going to seed. Hot soil is the culprit, so take steps to keep the soil cool for as long as possible. Mulch, regular water, and shade covers can prolong your broccoli season, and as the weather warms you should harvest more frequently to keep your plants from shifting into seed mode.
2. Planting and Spacing
Plant transplants that are 4 to 6 weeks old with four or five true leaves. Leggy transplants or transplants with crooked stems can be planted up to their first leaves so that they will not grow top heavy. Plant seedlings 18 to 24 inches apart in rows 24 to 36 inches apart.
Plant seeds and transplants at the same time for succession crops or plant early and mid-season varieties at the same time. Sow seed ½ inch deep and 3 inches apart. Transplant thinned seedlings to another part of the garden.
Broccoli Planting Tips
- Seeds: Unless you start seeds indoors over the winter, it may be difficult to grow a spring broccoli crop from seed, because the weather will warm too quickly. Fall crops are much easier to start from seed directly in the garden. Plant broccoli seeds about ¼ to ½ inch deep, and transplant to the garden in about 5 weeks.
- Transplants: Plant broccoli seedlings as soon as the ground can be worked in spring. If you’re planting broccoli transplants or seedlings, set them a little deeper in the soil than they were in the pot.
- Spacing: Space broccoli plants about 18 inches apart.
- Successive Plantings: Although the growing season is short for broccoli, you may be able to stagger plantings every 2-3 weeks for a longer harvest.
- Broccoli can germinate in soil with temperatures as low as 40ºF.
- Broccoli requires full sun and moist, fertile soil that’s slightly acidic. Work in 2 to 4 inches of rich compost or a thin layer of manure before planting.
- For spring plantings, seed or set transplants 2 to 3 weeks before last spring frost date. If you transplant, assume 10 less days for growth or the “days to maturity” on the seed packet.
- For fall plantings, seed 85 to 100 days before your average first fall frost. 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.
- Plant seeds ½ inch deep, or set transplants slightly deeper than they were grown originally.
- Within a row, space your plants 12 to 24 inches apart with 36 inches between each row.
- Space plants 12 to 24 inches apart, depending on the side heads you want to harvest.
- If you over-seed, you will need to thin seedlings to 12 inches apart to give room for the broccoli to grow.
3. Water and Feeding Broccoli:
Keep soil moist during the growing season. Decrease watering when plants approach maturity. Water broccoli at the base of the plant. Side dress plants with well-aged compost at planting time and again at mid-season.
4. Broccoli Care
Ensure to always keep broccoli planting beds weed free.
Broccoli Care Tips
- 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.
- Learn more about taking care of your broccoli plant.
5. Growing Broccoli in a Container
A single broccoli will grow in an 8-inch container. Grow multiple plants in larger containers set 18 inches apart. Broccoli is very sensitive to heat so be sure to move plants into the shade on hot days.
Broccoli Growing Conditions
- Planting: Broccoli is a cool-season vegetable that likes daytime temperatures in the 60s and can tolerate light frost and temps down to the 20s. Many gardeners plant broccoli in early spring for the main harvest, then leave the plants growing over the summer for a second harvest in the fall.
- Summer Heat: Broccoli will “bolt” (go to seed) in hot weather, which results in a loss of flavor and toughening of texture. Some varieties are more heat-tolerant than others.
- Light: Broccoli needs full sun, at least 4-5 hours per day.
- Soil: Broccoli likes rich, well-draining soil with a pH around 6. Because of the short growing season, broccoli is in a race against time and needs high-quality soil amended with plenty of rich compost. To improve drainage, you can plant your broccoli in mounds.
- Fertilizer: Broccoli benefits from regular applications of organic fertilizer.
- Harvesting: Broccoli seeds take 3-4 months from planting to harvest while transplants take 2-3 months.
6. Broccoli Pests and Diseases
Broccoli can be attacked by cutworms, cabbage loopers (preceded by small yellow and white moths), and imported cabbage worms. Control these pests by hand picking them off of plants or by spraying with bacillus thuringiensis.
Broccoli is susceptible to the cabbage family diseases yellows, club-root, and downy mildew. Plant disease-resistant varieties, rotate crops each year, and keep the garden free of debris to cut back the incidence of disease. Remove and destroy infected plants immediately.
- 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, a natural, bacterial pesticide. Use a floating row cover just after planting through harvest to prevent caterpillars.
- Cabbageworms and other worm pests: Treat same as loopers.
- Cabbage root maggots
- 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 blood meal. Blood meal is a quick nitrogen fix for yellowing leaves.
- 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 club-root 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.
Read Also: Comprehensive Guide on How to Grow Lettuce
Broccoli grown from seed will come to harvest in 100 to 150 days. Grown from transplants broccoli will come to harvest in 55 to 80 days. Cut buds when they are still green and tight.
Cut the central head with five to six inches of stem. Leave the base of the plant and some outer leaves to encourage new heads on secondary shoots. Heads that have begun to open showing small yellow flowers are past the eating stage.
Broccoli is ready to pick when the tops are dark green and full. Use a sharp knife to cut it straight across the stem. If you cut off the first large flower head that develops but leave the rest of the plant to grow, new side florets will grow. They’ll be smaller but still taste delicious.
If you wait too long to harvest broccoli, each individual green bud turns into a small yellow flower that forms seeds if left to grow.
- 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 your 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.
Broccoli will keep in the refrigerator up to one week or frozen after blanching for up to 3 months.
Broccoli Harvest and Use
- When to Harvest: When the main broccoli head is several inches in diameter, your broccoli is ready to harvest. The heads should be green, compact, and firm. If your broccoli plant produces side shoots, those florets may be smaller (but just as yummy). If left unharvested, broccoli heads will loosen and open into yellow flowers – if this happens, it’s too late.
- How to Harvest: Using a sharp knife, cut the main stalk of the broccoli at an angle, several inches below the flower head. Continue caring for the broccoli plant – it will likely begin producing side shoots and more broccoli!
- Storage: Fresh, dry broccoli will last in the fridge about 5 days in a non-airtight container. Wash broccoli immediately before use.
- Freezing: Broccoli freezes well. Cut the florets into pieces, then blanch the fresh broccoli by submerging it in boiling water for one minute, then plunging it into ice water to cool. Drain and dry, and pack the broccoli into airtight plastic bags.
Summary and Conclusion:
Broccoli grows best in cool spring and fall temperatures. It is one of the cole crops, the family of Brassica oleracea that includes Brussels sprouts, cabbage, cauliflower, collards, kale, and kohlrabi.
Warm climates may get three harvests of broccoli by planting fast-maturing types in spring, fall, and winter.
In regions with spring and fall frosts, time the plantings so you put broccoli plants in the ground in early spring and early fall. Some varieties have been bred for heat tolerance and grow through the summer, but most grow best when temperatures are between 65 and 80 degrees F.
If you plant too early in the spring and broccoli plants are exposed to 30-degree nights and 50-degree days, the broccoli may think it’s about to die and start prematurely producing tiny florets. This condition is called buttoning, which sounds cute, but the plants never produce larger heads.
Don’t be surprised if your broccoli heads don’t reach the same large size as the ones you buy in the supermarket. Because you’re picking the heads fresh and small, the broccoli should be very tender.