- Michigan State University - How to Grow Broccoli - MSU Extension
- West Virginia University - Growing Broccoli for Beginners | Extension Service | West Virginia University
- University of Minnesota - Growing broccoli in home gardens | UMN Extension
- Penn State - Broccoli | Diseases and Pests, Description, Uses, Propagation
Broccoli is actually a variety of cabbage! Wild cabbage was first cultivated in the Mediterranean area, probably in the time of Ancient Rome (before 1000 BC). Over countless generations, farmers have developed the different varieties in use today, including the cabbage we see in the grocery store, as well as brussels sprouts, cauliflower, kale, kohlrabi and broccoli, among others.
Broccoli is actually a variety of cabbage! Wild cabbage was first cultivated in the Mediterranean area, probably in the time of Ancient Rome (before 1000 BC). Over countless generations, farmers have developed the different varieties in use today, including the cabbage we see in the grocery store, as well as brussels sprouts, cauliflower, kale, kohlrabi and broccoli, among others. Broccoli is one of the most popular of modern vegetables, and is one of those that people feel strongly about. Glucosinates in broccoli and other cruciform vegetables cause a bitter taste, that some people strongly dislike, but for many people it’s just part of the overall flavor.
The flavor itself, as mentioned, does have a hint of bitterness, but that depends on the preparation, and in part on how it’s grown. Broccoli can be sweet, and rich tasting. Traditional recopies are prepared with basil, garlic, dill, rosemary, and other flavorful herbs that enrich the natural flavor of this flowering vegetable. The flavor is similar to brussels sprouts or kale in some ways, and the recipes featuring all of these vegetables are often similar. Broccoli is usually steamed, but can be roasted, or even eaten raw! Raw broccoli is sometimes bitter, but goes well with a good dip, like blue cheese dressing, or hummus.
Broccoli is very high in vitamin C, and vitamin K, and very high in fiber, but low in carbs. They also contain a sulfur compound, sulforaphane, which is starting to show up in studies as a possible treatment for cancer. Nutrition is similar in the various types of broccoli. They are also often similar in taste, though there are a few exceptions!
- Broccoli (Brassica oleracea var. italica)
- Biennial (annual)
- Full sun
- Soil should be slightly acidic (6.0 to 6.8 ph)
- Rich soil, with good compost
- Garden seed starting:
Thin to 12″-20″ apart when 2″ or more tall
- Garden transplant starting:
Container sized holes
Single plants in 12″ deep, and 12″ wide pots, spaced 12″ apart in larger pots
- Rows should be up to 36″ apart
- Water regularly, keeping the soil moist and the florets dry.
- Climate Zones 3-10
It’s important to note that broccoli is a cool weather plant. The bushy green part that we eat, the florets, is actually the flower of the plant. Broccoli is harvested for consumption early, while still green. Most often, broccoli is planted as an annual in the late-winter to early spring, and fully harvested before seeding late in spring or in early summer, before it gets too warm. If planted in the late summer, the florets can be harvested for eating in the cooler late fall. If some are left to over-winter, they will mature the following year, as in any biennial.
Calabrese is the most common type of heirloom (open-pollinated) broccoli. Another is Purple Sprouting broccoli, with branching purple florets, and is resistant to cold. Others include Waltham 29, which can be harvested throughout the season, and Romanesco, which looks a bit like a big cauliflower. Heirlooms are the ones you want if you intend to harvest the seeds. If you aren’t worried about seeds, hybrid broccoli can be a great choice! Some of these are more heat tolerant, like the aptly named Green Goliath, the Green Duke varieties, and the quickly growing Flash. There are many more.
If planting in the spring, it’s easiest to start the seeds early, indoors, and transplant the seedlings. Seeds should be started about eight weeks before the last frost. Plant each seed about 1/2 inch deep in a small, well drained container, and keep the soil moist and at room temperature. The sprouted seeds should be planted right at two weeks before the last frost. Well composted soil, and a low-nitrogen fertilizer is also a good idea when planting. It is ok to sow the seeds directly in the ground, two weeks before last frost, though this will result in a later harvest.
For warmer zones (8-10), it may be easiest to sow the seeds directly in the ground in late summer, for harvest in the fall. In zones 5 to 7, it’s possible to do two plantings for spring and fall harvests, if it’s timed right. Cool weather is best! The ideal soil temperature should be 65-75 degrees Fahrenheit (18-24 C) throughout the season, but cooler is better than warmer as the plant matures. Whenever you plant, mulch around the seedlings to shade the soil.
Broccoli can also be grown in containers. For a full sized plant sow singly in a container 12 inches deep, and 12 inches across (or larger). They can be evenly spaced at about that distance in a larger container, for smaller plants. Seeds or seedlings can be planted, just like garden broccoli. Avoid pots that are dark in color. Dark containers can easily heat up in full sun and cause the plant to bolt. The container should also have good drainage, since this plant must be watered frequently. The soil should usually be a vegetable plant mix, for containers. Be careful if garden soil is used, it should have the right nutrients, and no weeds or other seeds. Low-nitrogen fertilizer is essential for container plants when planting, and at least once during the season.
Companion plants that do well with broccoli include potatoes, lettuce, and spinach. Herbs such as dill, basil, and thyme work very well in this regard, as does lavender! Don’t plant different types of heirloom broccoli near each other if you want to harvest the seeds, as bees will cross-pollinate, and you won’t know what you will get!
Pests such as aphids and cabbage worms can also be a problem. Aphids can be washed off with a water spray with a bit of dish soap. Treating with neem oil is a good solution for a bigger aphid issue. Lavender attracts ladybugs, which makes it a great companion plant. Keep an eye out for very light gray or white moths near your plants, as these can leave cabbage worm larvae that eat the leaves. These can be picked off by hand, but wear gloves, and make sure to dispose of them well away from your garden.
Common diseases include clubroot and downy mildew. With clubroot the roots become enlarged. You will also see yellowed and wilted leaves, and eventually, too-small florets. The only solution for this is to pull the plant out, and dispose of it away from compost piles. Downy mildew can be seen by browned spots on the edges of the leaves, and a furry growth under the leaf. This can be treated, copper fungicides can be effective. Crop rotation is the best preventative for downy mildew.
Harvesting broccoli is pretty simple. At about 60 to 80 days from first seeding, the head should be tightly packed. Cut off the floret with several inches of the stem. Harvest immediately if it has started to turn yellow. If there are side-stems, these will grow into new florets that can be harvested later in the season. If you are harvesting seeds, allow some to yellow and flower completely. Cut the stems, separate the seeds, and allow them to dry completely. They can be stored for the following season!