How To Grow Broccoli – A Complete Guide from Seed to Harvest

Broccoli (Brassica oleracea var. italica) is a nutrient-rich vegetable which can be used in a variety of ways in the kitchen. It’s loved for its dense clusters of edible flower buds and sturdy stalks that are rich in vitamin C, vitamin K, fiber and phytonutrients. Growing it at home can give gardeners a double harvest: Once its sturdy head is harvested, a series of smaller side shoots continues to grow as a bonus!

This crop thrives in cooler temperatures and is typically planted for a spring or fall harvest. With consistent moisture and the right timing and soil conditions, broccoli will produce a bountiful crop in gardens from USDA Hardiness Zones 2 to 11.

Broccoli is relatively easy to grow, and is a great choice for anyone starting a vegetable garden. Fresh, blanched, baked or roasted, broccoli is not only a crop deserving of space in your garden but it’s also a star in the kitchen.

Quick Broccoli Facts

What is Broccoli?

Broccoli (Brassica oleracea) belongs to the large family Brassicaceae/Crucifera, which includes other vegetables like Brussels sprouts, kale, collard greens, cauliflower, cabbage, and kohlrabi. Broccoli is a cool weather plant originating from Asia Minor and the eastern Mediterranean. This Brassica has been harvested from at least the first century AD, when the Roman naturalist Pliny the Elder wrote of his people's enjoyment of broccoli. In modern gardens, broccoli took a while to catch on. Eaten in Italy and other Mediterranean areas, the name broccoli means “little sprout” and it was in these Italian neighborhoods of North America that broccoli first made its appearance. While broccoli was grown in the 1800s, it wasn't until 1923 when it was first shipped from the west that it gained in popularity.

Many don’t realize that there are several different types of broccoli with different forms, colors and harvest times. For instance, broccoli romanesco produces lime green heads packed with smaller florets. Broccolini is a form of “baby broccoli” with very small florets and a tender stem with large, edible leaves. Add a little color to your broccoli rows with purple sprouting broccoli, which is not only colorful but also extremely cold hardy and produces multitudes of tender side shoots in addition to its head.

Whichever of the dozens of broccoli you choose—maybe the cold and heat tolerant Green Goliath or the Italian heirloom Di Ciccio—planting and growing on this crop is more than rewarding. Burpee.com has several delicious broccoli varieties available, and several different purple types as well.

Planting Broccoli

As a cool-season plant, knowing when to plant broccoli is the key. If harvesting broccoli plants in midsummer is desired, it's best to start broccoli indoors 6 to 8 weeks before the last frost date. When broccoli seeds are sown outside, they’ll germinate within 4 to 7 days when ambient temperatures remain between 45- and 85-degrees F. (7 to 29 C.). For a fall crop, broccoli can be direct-seeded into the garden in midsummer.

When to Plant Broccoli

If using broccoli seeds you started indoors, wait until frost-free weather has arrived before transplanting spring seedlings in the garden. Be sure to harden plants off by gradually exposing broccoli seedlings to direct sunlight and wind.

Broccoli transplants purchased at a garden store are more than likely already acclimated to outdoor temperatures. If planting very early in spring, do keep an eye on the forecast and if the temperatures dip much below freezing, add protection such as a frost cloth until the cold temperature threat is gone. The Home Depot has numerous types of frost cloths available, such as the Planket in many sizes.

Best Soil for Broccoli

Broccoli prefers a slightly acidic soil pH of 6 to 7. Try growing broccoli in an organic, rich soil and fertilize seedlings and young transplants to maintain steady growth. Use a balanced fertilizer, as too much nitrogen promotes excessive leaf growth. Potassium and phosphorus encourage bloom development.

Broccoli Light Requirements

Broccoli prefers full sun. Choose a garden location which provides a minimum of 6 to 8 hours of direct sunlight daily.

Broccoli Planting - Step by Step

1. Choose the right time. Broccoli is a cool-season crop that grows best in spring and fall. For a spring harvest, start seeds indoors 6–8 weeks before your last expected frost and transplant outdoors 2–3 weeks before that date. sow them ¼ to ½ inch (6 to 13 mm.) deep in a quality seed-starting mix or soil pellets. When growing broccoli seedlings indoors, be sure to provide plenty of light to prevent plants from becoming leggy. Or, purchase broccoli transplants at your local garden center and plant when your garden’s soil is workable. For a fall crop, sow seeds directly in the garden in mid- to late summer, about 10–12 weeks before your first fall frost.
2. Select a planting site. Plant broccoli in a spot that receives 6–8 hours of full sun daily. In warmer climates, light afternoon shade can help prevent heat stress and bolting.
3. Prepare the soil. Broccoli prefers fertile, well-drained soil with a pH of 6.0–7.0. Work 2–3 inches (5–7.5 cm) of compost into the top 8–10 inches (20–25 cm) of soil before planting. This heavy feeder thrives in nutrient-rich conditions.
4. Sowing or planting oudoors. Sow seeds ½-inch (1.25 cm) deep and 4-5 in. (7-8 cm) apart when ambient temperatures remain between 45- and 85-degrees F. (7 to 29 C.). If using transplants, space broccoli plants 12 to 24 inches (30 to 61 cm.) apart. Providing more space between plants encourages larger central heads.
5. Thin seedlings and water. If you sowed seeds, thin them to the final 12 to 24 inches (30 to 61 cm.) apart. Keep soil evenly moist but not waterlogged.

Broccoli Care

Follow these tips to ensure your broccoli plants grow their best.

Watering

Broccoli needs about 1–1½ inches (2.5–4 cm) of water per week. Keep soil evenly moist but not waterlogged. Mulch around plants with 2 inches (5 cm) of organic mulch to conserve moisture and regulate soil temperature.

Fertilizing

Side-dress with a nitrogen-rich fertilizer or compost about 3–4 weeks after transplanting to encourage leafy growth and strong head formation. Use a balanced fertilizer, as too much nitrogen promotes excessive leaf growth. Potassium and phosphorus encourage bloom development. Espoma Organic Garden-tone is a 3-4-4 fertilizer for all sorts of vegetables and can be found on Amazon.

Mulching

Lay down a 1-to-3-in. (2.5-7.5 cm) layer of organic material like straw or shredded leaves around the base of the broccoli plants. This helps retain soil moisture, keep roots cool, and keep weeds down. Be sure to keep the mulch 1-2 in.(2.5-5 cm) away from the stems to prevent rot. Mulching with a product such as Miracle-Gro Organic All Natural Mulch from Lowe’s will even help deter premature bolting caused by heat stress.

Pruning

Broccoli doesn’t necessarily require pruning. Broccoli can also benefit from removing damaged or yellowing leaves. Do this by snipping the entire leaf stem at the base with clean scissors or hand pruners.

It’s possible to maximize the size of the broccoli heads by pruning a few of the larger leaves about 2 months into its growing time in order to redirect the plant’s energy into larger head production. Don’t chuck them! You can eat broccoli leaves, and they are just as usable and tasty in the kitchen as kale and collards.

Harvesting Broccoli

The edible part of the broccoli plant is the unopened flower. Ideally, the central head should be harvested when it's fully developed, but before the individual buds open into small, yellow flowers.

The harvest time for broccoli depends on several factors, mostly the type and variety but also your local conditions.

Signs which indicate broccoli is ready to harvest include a 4- to 7-in. (10 to 18 cm.) tight head with large, dense flower buds. If the buds begin to open, harvest immediately. If the plant has bolted (is flowering), it’s too late to pick it.

To harvest, use a sharp knife to remove the central flower head. Leaving the broccoli plant in the ground encourages side shoots (flower heads) to develop. Although smaller than the central head, these side shoots allow gardeners to continue harvesting broccoli for a longer period of time.

To maintain the quality of fresh-picked broccoli heads, harvest during the cool, morning hours and refrigerate as soon as possible. Unwashed broccoli heads can be stored in the refrigerator for 3 to 5 days. Blanched broccoli freezes well and maintains its quality for up to 12 months.

Storing Broccoli

Broccoli can be stored in the fridge for up to two weeks. Do not wash it before storing, as that will encourage mold. If you have a crop that doesn’t give you huge quantities, you can probably eat through your harvest without it getting tougher and losing nutrients the longer it is in the refrigerator.

For bumper crops worth of broccoli, you can store it several ways, including freezing (the most popular method), canning and pickling.

Propagating Broccoli

It’s possible to harvest and save broccoli seeds from your own garden and save them for planting next season. In fact, doing this has caught on and isn't too difficult.

The process does pose one bit of difficulty. Because broccoli is a cross-pollinator, it needs other broccoli plants nearby in order to pollinate. Any plant in the brassica family can provide that pollen—cauliflower, kale and so on. If you plan to collect and save your broccoli seeds for next year, you should probably plant only one type of brassica in your garden.

To save broccoli seeds, first choose broccoli plants that show the traits you wish to carry over into next year's garden. You may have to sacrifice eating your most delectable head and use it instead for seeds. Allow this broccoli head to mature and turn from green to yellow as the flowers bloom and then turn into pods. The pods are what contain the seeds. Once the pods are dry on the broccoli plant, remove the plant from the ground and hang to dry for up to two weeks. Remove the dried pods from the broccoli plant and crush them in your hands or with a rolling pin to remove the seeds. Separate the chaff from the broccoli seeds. Store the seeds in a jar or envelope and keep in a dry and dark place until use. Broccoli seeds remain viable for five years.

Once you’re ready, sow them indoors or directly in the garden as outlined above.

Broccoli Problems

Broccoli crops share pest and disease pressures with other members of the brassica family. Here are common broccoli problems to look for:

Pests

• Cabbage worms are the larvae of the Imported Cabbageworm and Cabbage Looper. These are green caterpillars that chew large holes in leaves and can burrow into heads.
• Aphids are small sap-sucking insects that cluster on stems and leaf undersides, causing curling and sticky residue.
• Flea beetles are tiny jumping beetles that create “shot holes” in young leaves.
• Cutworms are larvae that sever seedlings at soil level.
• Row covers, hand-picking, and encouraging beneficial insects help control many of these pests.

Diseases

• Clubroot is a soilborne disease causing swollen, distorted roots and stunted growth.
• Downy mildew leads to yellow patches on leaves and fuzzy growth underneath in cool, damp conditions.
• Black rot causes yellowing leaf edges and darkened veins, often spreading in warm, wet weather.

Other Common Broccoli Problems

• Not forming heads: This is usually due to extreme temperatures, overcrowding, or a damaged root system.
• Bolting: Broccoli will bolt or begin flowering when the temperatures become higher than they can handle.
• Buttoning: Broccoli “buttoning” means it has produced very small heads, and this has several environmental causes.
• Loose bitter heads: These will form when there are spikes in temperatures and excessive nitrogen.

Growing Broccoli in Containers

Broccoli grows well in containers and is a nice option for patios, decks and small-space gardens. Choose a pot that is at least 12–18 inches (30–45 cm) deep and wide for one plant, with ample drainage holes. Broccoli is a heavy feeder, so fill containers with a high-quality potting mix amended with compost. Place the container in a location that receives 6–8 hours of direct sun daily, although light afternoon shade can help in warmer climates. Keep the soil consistently moist (remember, containers dry out more quickly than in-ground beds) and every few weeks add a balanced liquid fertilizer or compost tea to support consistent growth. With proper care and timing, container-grown broccoli can produce full-sized central heads followed by smaller side shoots.

Growing Broccoli Indoors

Broccoli can be grown indoors, but it’s much more challenging than growing it outside. It needs cool temperatures and lots of light to form proper heads. A bright windowsill usually isn’t enough light to develop full heads, so you’ll need supplemental grow lights. Look for compact varieties and follow the planting directions for growing in containers.

Consider growing broccoli microgreens indoors instead. They require much less space, mature quickly and don’t demand as much light intensity.

Companion Planting with Broccoli

Companion planting means a beneficial relationship ensues when certain plants are planted near each other. This is part of the science and art of nature. Broccoli has companion plants that, when planted with it, benefit one or the other—or both!

Dill, rosemary, sage and mint contain scented oils that repel insects such as cabbage flies. Celery, potatoes, and onions are said to improve broccoli’s flavor, as is chamomile. Geraniums not only add some floral color to a veg planting but can also help cabbage worms stay at bay. Burpee.com has a fun collection of herbs called the Colonial Dooryard Herb Collection that celebrate the herbs colonists relied upon the most.

Frequently Asked Questions

Broccoli Growing Essentials

• A great broccoli harvest starts with quality seeds— Burpee.com has several delicious broccoli varieties available.
• Frost cloth is an essential cold-weather protector—Home Depot has numerous styles and sizes of Planket for keeping your broccoli from getting to chilly.
• Conserve moisture and help deter heat stress-induced bolting with Miracle-Gro Organic All Natural Mulch from Lowe’s.
• Keep nitrogen in check and control leafy growth—use a balanced fertilizer such as Espoma Organic Garden-tone.
• Grow herbs as companion plants—Burpee.com’s Colonial Dooryard Herb Collection has herbs that worked in the kitchen and in the garden.