Growing Broccoli – A Complete Guide

Growing broccoli in your garden is a pleasingly rewarding process. Broccoli (Brassica oleracea) is a versatile vegetable. It is also a surprisingly nutritious vegetable full of minerals and vitamins such as folic acid, potassium, Vitamin A iron and fiber.

Broccoli is a cool season, sun loving plant. It is usually grown in the spring or fall.  The plant belongs to the brassica or Cruciferae family. Broccoli is a close relative of collards, brussels sprouts, bok choy, cabbage and cauliflower.

Adaptable and resilient this vegetable doesn’t require lots of space to thrive. It is also one of the easiest vegetables to cultivate. This is your complete guide to growing broccoli.

Packed full of nutrients, growing broccoli is a surprisingly easy process. 

What is the Difference Between Broccoli and Calabrese?

Many gardeners and casual observers confuse, or struggle to tell the difference between, broccoli and calabrese. While they may look similar, the two plants have different growing requirements. Calabrese is a fast growing crop that is harvested in the same year that it is sown. Broccoli is overwintered and harvested the following year.

Different Varieties

Growing broccoli requires cool temperatures. Warm weather can stunt the growth habit of the plant. The plants thrive in temperatures between 65 and 70 ℉. You will need to plan your crops around the high, summer temperatures.

In cool areas you can begin growing broccoli in early spring or mid summer. Growers in warmer areas should plant quick growing varieties in late summer. This allows your crop to avoid the highest temperatures of summer.

Recommended varieties include:

• Bordeaux F1 is a reliable late year variety. It produces purple spears from early summer until late fall and requires no cold period to begin producing the spears.
• Claret F1 is a popular purple hybrid. It is known for its thick spears which emerge from April onwards. This is a vigorous cultivar that does well in poor soils.
• Nine Star Perennial is a reliable cultivar which produces small pale stems every spring for up to 3 years. A vigorous variety, it does best with a little space.
• Green Goliath is a popular heat tolerant cultivar. It is grown for its large heads and side shoots.
• Green Magic is another heat tolerant variety. A reliable plant it’s stalk also freeze well.
• Green Duke is heat tolerant and reliable, a popular choice amongst gardeners in the South or warmer climates.
• Flash is another heat resistant, quick growing variety. Once the head is cut the plant produces scores of side shoots.

The range of varieties on offer means that you will be able to find at least one type that is suitable for your climate. 

Broccoli can be started either from seed or purchased as young plants. Seeds are easy to start and cheaper than plants. Growing from seed also allows you access to a wider range of plants.

Growing from Seed

Seeds store for up to four years so don’t feel you need to use the entire packet in the first year. How many seeds you sow depends on how much broccoli you require, and how many people you are feeding. Smaller families will find two or three plants more than enough.

In cool areas, sow the seeds from April to June. Planting in this timeframe allows you to harvest crops from February or March until early May. In warmer areas sow quick growing seed varieties either late in the summer or in early fall.

Seeds germinate in temperatures as low as 40 ℉. However, the warmer the soil the quicker germination occurs.

If you are sowing in the spring, sow seeds indoors 6 to 8 weeks before your last predicted frost date. Sow outdoors 2 to 3 weeks before the last frost, as soon as the soil can be worked.

In the fall, sow seeds 85 to 100 days before the first predicted frost. At this point the soil and temperature is warm enough to encourage germination but not too warm that it stunts growth.

Sow the seeds in trays filled with fresh potting soil. You can also sow directly into position in a bed. To do this dig over and weed the soil well before sowing. Your chosen site should be full sun, ideally 6 to 8 hours a day.

Planting in darker positions may cause plants to underdevelop or become leggy. A sheltered site is preferred, this helps the plants to survive cold winters.

Plant in moist, well draining, fertile soil. Work in compost or a light layer of manure in early spring to enrich the soil.

Before planting, use a soil test kit to measure the pH level of your soil. It should be between 6 and 7. Growing broccoli is best done in a slightly acidic soil. If your soil is too alkaline, there are a number of easy ways to amend it.

Sow the seeds about half an inch deep. Aim to space them about 12 inches apart. Some varieties may require more space, check the seed packet before sowing. Don’t worry if you struggle to space the seeds out far enough. They can be thinned out later, following germination.

Place a net over the seeds or a floating crop cover. This protects the seeds and young plants from pigeons or other birds. The ChangSheng Plant Cover not only protects seedlings from birds, it also prevents smaller pests such as caterpillars from accessing your crops.

Planting Broccoli

Remember to harden off seedlings before transplanting.

Seeds started indoors can be transplanted when they are 4 to 6 weeks old or when 4 to 5 leaves have developed. Plant slightly deeper, about an inch, than their tray depth.

Space the plants 12 to 20 inches apart. Rows should be spaced 3 ft apart. Planting too closely together can cause main head yields to be smaller, however more secondary heads will develop.

Planting in Containers

You can also try growing broccoli in a pot. One plant comfortably fits in an 8 inch pot. An 18 inch pot can hold 3 to 4 plants. Plant as you would in the ground. Planting in self watering pots helps to keep plants hydrated in a low maintenance garden.

Fill the pot with fresh, well draining potting soil. Plant each plant slightly deeper than in its previous position.

After planting, firm the soil down and water.

An uncomplicated plant, you can also grow broccoli in pots.

Caring for Growing Plants

Thin the plants out when they reach 2 to 3 inches in height.

Keeping the beds weed free is important. There are a number of useful weeding tools that can help you achieve this. However, growing broccoli has shallow roots. Disturbing the roots can impair growth. Instead, try mulching around the plants. This also helps to keep the soil cool and encourages the plants to continue growing during warm periods.

When to Water

Aim to keep the soil evenly moist. Water regularly, especially during drought, or warm periods. In general you may need to apply one to one and a half inches of water a week.

Try to keep the plant, in particular the head, as dry as possible when watering. Damp heads can easily rot. Watering with a watering can, instead of a hose, can make this easier.

Once the heads have formed reduce watering.

You will need to water broccoli growing in pots more often than plants in the ground. You can also move the pots to shadier positions on hot days. This helps the soil to conserve moisture and also keeps these heat sensitive plants cool.

Watering cans allow you to keep as much of the plant as possible dry while still soaking the soil. You can also dilute water soluble or liquid fertilizers into a watering can.

Fertilizing your Plants

Apply a low nitrogen fertilizer three weeks after transplanting. If you have started the seeds in beds, fertilize three weeks after thinning out.

Add bone meal if the lower leaves, followed by the top leaves, yellow.

A nitrogen rich liquid fertilizer can be applied in the spring to encourage better heads to form. Liquid fertilizers are easily incorporated into a watering routine.

Wind Protection

Earth the soil around the stems of the plant to prevent wind from knocking or rocking the growing stakes. Mound the soil about 4 inches high. In windier positions you may need to stake the growing plants. Royal Imports Wood Plant Stakes provide a sturdy, natural way to support growing plants.

Companion Plants

Broccoli is a cool weather crop, like kale and beets. These make great companion plants as do potatoes, celery, onions, hyssop and wormwood.

Growing broccoli alongside fragrant herbs also has benefits. Dill, oregano, chamomile, mint, rosemary, thyme and culinary sage are all great choices.

Like many crops, broccoli emits allelochemicals. These can adversely affect plants growing closeby. Choose your companions carefully. Avoid planting near pole beans, tomatoes, beans, mustards and strawberries.

Common Pests, Problems and How to Solve Them

Broccoli suffers from many of the same problems as other brassica plants.

Clubroot is a particular problem. Clubroot causes roots to become gnarled and misshapen. Lift the plants as quickly as possible and destroy them. Don’t place diseased plants or infected soil on the compost heap.

Prompt action prevents the disease from spreading to other plants. Raise the pH level of the soil to over 7.2 to get rid of the fungus. You may also need to sterilize the soil.

Plants growing on even the smallest allotments can benefit from a simple crop rotation system. 

The yellowing of foliage at the bottom of the plant, slowly rising up the stem, is a sign of a nitrogen deficiency. This can be cured by amending the soil with a nitrogen heavy, low phosphorus fertilizer. Blood meal can also be used, and offers a quicker solution.

Regularly check plants for signs of infestation such as aphids. These can be removed by an application of homemade insecticidal soap.

Cabbage loopers, creating small holes on the foliage, can be picked off the plant. A floating row cover prevents most caterpillars. Cabbage Worms can also be picked from the plant.

Whiteflies, white rust and cabbage root maggots can also affect crops.

Adopting even a simple form of crop rotation can help to alleviate or prevent most issues.

How to Harvest Crops

Broccoli is best harvested in the morning. Harvest stalks when the buds on the head are firm and tightly packed together.

Harvest plants when the buds are still firm and tightly packed together. 

Harvest immediately if you notice petals yellowing. As soon as the petals begin to yellow the quality of the plants will decline quickly.

Use a sharp knife, such as the Zenport Crop Harvest Knife, to cut the head and about 6 inches of stem.

When harvesting try to make an angled cut. This helps water to slide away from the stalk. Water pooling on flat surfaces can cause the stalk to rot. This ruins any secondary heads that may form.

Once the main head has been harvested, allow the plants to remain in place. Continue to water and fertilize the plants. Many varieties form secondary, smaller heads.

Secondary stalks can continue to emerge for many weeks after the main harvest, especially in cooler climates. These can be harvested and used just like the main stalks.

Storing Stems

Freshly harvested stalks often taste better than stored stalks. Steaming the stalks also helps to retain flavor and texture as opposed to boiling. Freshly harvested broccoli can be stored for 5 days in a refrigerator. Wash thoroughly before storing.

If you need to store the stalks for longer, blanch and freeze them. Stalks treated in this way can be stored for up to a year.

Surprisingly easy to grow, these plants are packed full of nutrients. 

Growing broccoli is one of the easiest vegetables you can introduce to your garden. With regular water and a little nutrition the plants will thrive, producing a reliably stream of nutritious and great tasting stalks. Despite being a cool weather crop, even gardeners in warmer climates can enjoy some success by growing quick growing varieties. Reliable and resilient and packed full of nutrients, why not start your growing broccoli journey today?