How To Grow And Care For Broccoli

Learn to grow broccoli in your backyard garden.

Fact checked by Khara Scheppmann

If you have never grown broccoli (Brassica oleracea) in the garden, you might be surprised to learn that the part of the plant we eat is a flower, or more precisely, a cluster of immature flower buds harvested before they open. Broccoli has an interesting growth habit, one developed through thousands of years of cultivation. The dome-shaped flower head grows on a thick stalk.

Harvest 50-90 days after spring planting to enjoy in early summer. To understand how to grow broccoli in the garden, it is helpful to know how broccoli grows and develops before you plant a broccoli crop.

The Origins Of Broccoli

Broccoli and its relatives—cabbage, mustard, Brussels sprouts, cauliflower, kale, kohlrabi, and others—all began as the same plant: a wild mustard. Through thousands of years of human selection and breeding, different cultivars were developed from these wild plants. Plants that produced desirable foliage were selected and bred into mustard and kale, while those with large terminal buds led to the many types of cabbages available today. Brussels sprouts were bred from plants that produced large lateral buds along the shoots. Broccoli plants, as well as cauliflower, were selected for their dense flower heads.

The earliest broccoli plants looked quite different from those grown today, but over time and through human selection, plants came to produce larger and larger flower heads. Most varieties grown today produce a large dome-shaped flower head on a thick stem rising above a rosette of large basal leaves. Producing those large heads requires large amounts of water and nutrients to feed the basal leaves, which produce energy necessary for flowering.

Plant Attributes

Broccoli Care

Broccoli is an enjoyable crop to grow and great for gardeners looking to try something new. The heads are incredibly nutritious, with substantial amounts of protein, calcium, and iron. They are also packed with vitamins, including (vitamin A) and ascorbic acid (vitamin C).

Like most vegetable crops, broccoli plants require full sun and rich, well-draining soils. Broccoli plants are heavy feeders and will benefit from incorporating organic matter and nitrogen into the soil at planting time, and regular fertilizing through the growing season. Space plants 18 inches apart and water well. Maintain even moisture throughout plant development and fertilize about three weeks after transplanting to feed those growing plants.

Light

Grow broccoli plants in full sun, about six hours of direct light each day. Some afternoon shade may be necessary in very hot climates where too much sun can cause the plant to flower and go to seed too early.

Soil

Plant broccoli in rich loamy soil with a lot of organic matter and a neutral pH. Make sure the soil is well draining.

Water

Give broccoli plants even moisture during development. The soil should not be soggy. Water around the base of the plant instead of overhead to prevent rot. Add a layer of mulch around the base to keep it from drying out.

Temperature And Humidity

Broccoli plants are cool-season vegetables requiring cool air and soil temperatures to grow.  Plants are very cold hardy, but do not tolerate heat well. As such, broccoli is planted in spring for an early summer harvest. Plant quality will decline as temperatures reach above 80˚F.

Fertilizer

Give regular fertilizer throughout the growing season, starting with planting time and again three weeks after transplanting.

Types Of Broccoli

If you live in a hot climate, look for fast-maturing varieties to ensure a crop before high temperatures arrive. Another option is to grow broccoli relatives like Raab and Gai Lan, which have relatively short maturation periods. Types of broccoli include:

• ‘Calabrese’: This fast-growing variety produces large blue-green heads with multiple side shoots.

• ‘Broccolini’: Long, thin stalks and small florets have a sweet flavor with notes of asparagus.

• ‘Chinese Broccoli’: Also known as Gai Lin, thick stems and collard-like leaves are the main parts that are eaten.

• ‘Green Goliath’: This variety is good for home gardens as it grows very large and heads mature in three weeks.

Pruning

Broccoli plants generally don’t need pruning but you should remove any diseased or damaged stems from the plant when you see them to avoid potential weakening of the plant.

Propagating Broccoli

Exact planting time varies depending on location but can be estimated based on the last spring frost date for your area. Broccoli seeds are typically started indoors, and the seedlings are transplanted into the garden two weeks before the last spring frost date. Seedlings can be purchased at your local garden center. If you prefer to start your plants from seed, sow seeds indoors six to eight weeks before your last frost date. Broccoli needs about four to six weeks from seeding until the plants are ready to transplant.

How To Grow Broccoli From Seed

Broccoli grows best from seed. They can be planted outdoors or started indoors. Here’s how:

1. To plant seeds outdoors, place them 1/2 inch deep and 3 inches apart in full sun and well-draining soil.

2. When seedlings are 2 inches tall, thin them out so they are spaced 18 inches apart.

3. For seeds started indoors, after six weeks, plant the seedlings 18 inches apart. Space rows 3 feet apart.

4. Water well and give the plants consistent moisture as they grow.

When To Transplant Broccoli

Broccoli plants are typically transplanted into the garden when they have just four to six small leaves. These leaves capture the sun’s energy and, through photosynthesis, produce food for the growing roots, stems, and foliage. With each new set of leaves, the plant’s ability to capture sunlight and turn it into energy increases, making the plants grow more quickly. This vegetative growth continues, with plants growing upwards and outwards, while also storing energy for future flowers.

When To Harvest Broccoli

Once the plant has stored enough energy to bloom, it shifts resources from vegetative growth into flowering. For most broccoli varieties, that energy is directed to the flower bud at the top of the main stalk. The flower bud expands, its stem thickening as hundreds of buds develop into what we commonly call a crown or head. These heads are harvested while the flower buds are small and still tightly closed, and heads are 4 to 6 inches across. If left to grow too long, the flower buds will elongate and open, revealing hundreds of yellow blooms. Following the harvest of the main head, smaller heads will form along the remaining side branches. These can be harvested and eaten as well.

Potting And Repotting Broccoli

Broccoli can be planted in pots using organic vegetable potting mix. Make sure the pot drains well, and keep the soil moist but not soggy. It can grow quite large and the roots need plenty of room to grow, so use a container that’s at least 12 inches wide and deep. Plant broccoli in a large pot that can accommodate its growth so repotting, which could disrupt the root system, will not be necessary.

Overwintering

Broccoli is not a winter crop so overwintering isn’t necessary. Plant fall crops early enough to harvest before freezing temperatures. Harvest any mature broccoli that’s still on the stalk before the first frost.

Common Pests And Plant Diseases

A simple trick at planting time can save plants from a devastating pest called cutworms, which can wipe out an entire row of plants overnight. Cutworms are moth larvae that feed on the plant stems at the soil surface, often chewing through the entire stem and removing the plant tops. Protect transplants by placing a stick, pencil, or straw alongside (touching) the plant stem. The cutworms need to encircle the stem completely to feed and the stick disrupts this behavior.

Another option is to plant seedlings inside rings made from toilet paper or paper towel tubes sunk one to two inches into the soil. Cutworms feed right at ground level and these rings (often called collars) create a barrier between the worms and the plants.

One of the main pests of broccoli plants are cabbage worms, a complex of three butterfly and moth species: the cabbage looper, diamondback moth, and imported cabbageworm. Row covers will keep these pests at bay by preventing adults from laying eggs on the plants.

Broccoli diseases include brassica downy mildew and brassica white blister. Apply fungicide to treat. Rotate your crops to different planting sites each year to control diseases.

Frequently Asked Questions

Can broccoli grow in a container?

Broccoli can be grown in a container that is at least 12 inches wide and deep. A 5-gallon pot works well. Plant only one broccoli plant per container. Give the plant partial shade so the temperature does not go higher than 80°F as the container heats up in the sun.

What should not be planted with broccoli?

Plants that are attractive to the same pests and diseases or with similar growth requirements shouldn’t be grown together. Avoid planting broccoli near bushy or spreading plants like tomatoes, squash, and eggplant or similar plants like cabbage and cauliflower where they’ll compete for the same nutrients. Good companions include lettuces, radishes, celery, onions, and rosemary.

How many heads does one broccoli plant produce?

Each broccoli plant produces one head of broccoli. Smaller florets grow off the leaf stalks of the main stem after the head is harvested. These are also edible.

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