Broccoli is a delicious, nutritional-powerhouse vegetable that’s hard to beat. It is a member of the cabbage family (Brassicaceae) but unlike cabbage, it is eaten for its flower heads and stalks, which are packed with vitamin C and vitamin K as well as iron and other minerals. Broccoli was first developed in the ancient Roman Empire, and has traveled over the centuries to become a favorite all over the world. Read on to learn how to grow this classic in your own garden!
How to Grow Broccoli
Growing your own broccoli takes a little more patience and know-how than many other green vegetables. Broccoli takes longer than other greens like kale and cabbage to mature, since you are waiting for the flower stalks rather than harvesting leaves. Then, once the florets arrive, the harvest window is quite short, so you have to be paying close attention! But, anyone can successfully grow broccoli by following the right steps.
When to Plant Broccoli
Broccoli is a cool-season vegetable that does best in temperatures between 65 and 75 degrees F, and the heading (flowering) process will be disrupted by hot weather, so you’ll need to time your planting so that heads can form either before or after the heat of the summer. For most gardeners, that means starting seeds indoors in seedling trays 6-8 weeks before the average last frost date for spring harvest, or direct-sowing outdoors in mid- to late summer for fall harvest.
How to Plant Broccoli
If starting broccoli seeds indoors for spring harvest, sow the seeds 6-8 weeks before your average last frost date. Learn more about growing your own transplants on our blog post about starting seeds indoors. If you’re planting for fall harvest, sow the seeds directly in the garden, 80 to 100 days before your area’s average first frost.
Broccoli Growth Stages
Broccoli takes about 80 to 100 days from seedling to mature and produce heads.
Germination and Seedling Stage
Most of the time, broccoli seeds will germinate within 7 days of planting, but if the soil temperature is cool, it may take longer. Optimal germination temperature for broccoli is 50 to 85 degrees F. Once the seedlings are up, be sure to thin them after they get their second set of adult leaves. (The first pair of leaves that emerge from the seed are called cotyledons or “seed leaves” and will be heart-shaped and rounded. The adult leaves will begin sprouting in pairs a few days later, and look more like kale.)
Pro tip: broccoli greens are edible (and delicious!) and you can eat the seedlings you pull out when thinning. If you’re seeding outdoors for a fall planting, it might even be worth seeding extra with greens in mind. Seedlings are ready to transplant outdoors once they are 4-6 inches tall, and the threat of frost has passed. Make sure the bed you plant them in has full sun (6 or more hours per day), and has been well prepared by working in an inch or so of compost. Transplants should be 18-24 inches apart to allow them plenty of room to grow.
Broccoli will spend about the first 45 to 65 days after planting in the vegetative stage, just growing larger and putting out more leaves. During this period, it’s important to make sure the plants receive at least an inch of water per week. It’s also a good idea to apply a balanced fertilizer about 3 weeks to a month after transplanting.
Some gardeners like to harvest a few leaves off their broccoli plants for greens during this phase. A well-established broccoli plant can handle losing a few leaves and still produce a good head, but be careful. If you take too many leaves, you’ll slow down the plant’s development and it will have less energy to invest in the flower stalk. If you’re set on harvesting the largest, healthiest broccoli head possible, just refrain from harvesting any greens.
At around 45 to 65 days, your broccoli plants will begin to create flower stalks. If the variety is a heading type, it will grow one thick flower stalk in the center of each plant, or if it’s a sprouting type, it will make several smaller stalks. As the heads are developing, take extra care to water from the base of the plant, as the heads tend to catch and hold water, which can lead to rot. Once you see heads forming on your broccoli, be sure to check on your plants every day, so you can harvest at just the right time.
To know when your broccoli is ready to harvest, look for the heads of the expected size for your variety (check the type description on your seed packet), and heads that are dark green and still compact and rounded in shape. You’re trying to catch the flower head when it has reached maximum size, but just before the flowers start to open.
If you see any buds beginning to open into yellow flowers, harvest immediately! When a broccoli head blossoms, it turns bitter and the texture of the head is ruined. If the cool season is long enough where you are gardening, you might be able to get a second harvest from your broccoli plants. Second-growth heads will sprout out around where the main head was, and will be smaller.
How to Store Broccoli
Broccoli will store in your fridge for about one week if it is unwashed. Washing gets the heads waterlogged and encourages rot, so only wash your broccoli when you’re ready to use it. The best long-term storage option for broccoli is freezing. In fact, it retains its texture after freezing better than almost any other vegetable. To freeze your broccoli, cut the heads into bite-size florets, then blanch them in boiling water for about 2 minutes. Dunk the florets in a bowl of ice water to stop the cooking process, then drain and allow them to dry thoroughly before sealing them in a plastic bag or other airtight container, and place them in the freezer.
Another tip: don’t waste the stems of your broccoli! Broccoli stems are sweet and delicious, though the outer skin of some varieties can get tough and stringy. If that’s the case, use a vegetable peeler or knife to remove the darker colored outer layer and save the light colored, tender inner part.
Photo: Russ Ottens, University of Georgia, Bugwood.org
Pest & Disease Prevention
Just like any garden plant, broccoli is susceptible to a number of pests and diseases. And, as with any garden plant, the first and best defenses are crop rotation, and attracting beneficial insects and wildlife to your garden with diverse plantings. Here are some tips for controlling some of the most common broccoli pests.
Aphids are easily the most common pests for most garden vegetables, but also one of the easiest to control. On broccoli, the biggest concern when you see aphids isn’t necessarily the amount of damage they do to the plants, but the fact that they carry disease. If you’re seeing lots of aphids on your plants, just a spray of soapy water on the leaves will usually take care of them in short order. Dish soap or natural castile soap will work.
Cabbage Loopers and Other Caterpillars
A number of different caterpillars love broccoli, but cabbage loopers (the larvae of the small white moths often seen around Brassica plants) are the most common. Generally, most home gardeners just keep a close eye on their plants, and pick off any caterpillars they see. If an infestation gets particularly bad, spraying Bt (Bacillus thuringiensis) can be a good short-acting organic solution. Just be sure to only spray Bt on the plants affected, and avoid overspraying, as the bacterium will also harm non-pest caterpillars and other soft-bodied insects.
Keeping young plants under row cover until they are well-established can also minimize damage from caterpillars and other insects. And last but not least, planting a border of diverse pollinator-attracting plants and providing semi-wild habitat around your garden can help bring in beneficial wildlife like birds, ladybugs, mantids, toads, and yellowjackets (yes, yellowjackets! Unpleasant though they may be, they eat many different caterpillar species.)
Fungal, Bacterial, and Viral Diseases
There are a wide range of plant diseases that can affect broccoli, but the best defenses against all of them are crop rotation, proper spacing between plants for airflow, good watering practices, and good soil fertility for vigorous plants. Try not to plant your broccoli in the same spot where other Brassicas have been within the last three years and make sure the plants are at least 18 inches apart.
Water only from the base of the plant as much as possible, and avoid leaving the soil waterlogged for extended periods by overwatering. Prepare your soil with compost before planting, and give your broccoli a boost with a low-nitrogen fertilizer about three to four weeks after transplanting (or about two months after seeding.) It’s also worth noting that many bacterial and viral diseases are spread by insect pests, so keeping infestations under control can help prevent further disease.
If you’re seeing symptoms like wilting, yellow or brown spots, or fuzzy moldy growth on your broccoli plants, it’s worth trying an organic fungicide/pesticide like Dr. Zymes. If you have persistent issues with disease in your garden, your local extension agent can be a great resource to help you diagnose exactly what pathogen is the culprit, and determine the best control method.
Broccoli vs. Broccoli Rabe
Though the two plants are grown in similar ways, broccoli rabe (aka rapini) is actually a totally different species, Brassica rapa, more closely related to mustard greens and turnips than cabbages. Rapini is traditionally eaten for both its greens and florets, which are smaller and more loosely-formed than broccoli heads. It tends to have a little stronger, more bitter taste than broccoli - but some people love that! If you find yourself frustrated with growing broccoli, trying rapini instead might be a good idea. It matures more quickly than broccoli, and the smaller heads are less susceptible to fungal and bacterial diseases.
Best Broccoli Varieties for Your Home Garden
One of the oldest and most well-loved heirloom broccoli varieties, Di Ciccio is known for its high productivity, sprouting multiple side shoots in addition to a main head.
Hardy Waltham 29 was developed by researchers at the University of Massachusetts in the 1950s, and makes an especially good fall crop, as it easily tolerates dropping temperatures. Produces large heads with long stalks.
Green Sprouting Calabrese
Green Sprouting Calabrese is prized for its short time to maturity, and for its long harvest window, as it produces plentiful side stalks around a relatively small central head.
Some people call Romanesco broccoli a cauliflower, but that’s really just a matter of Brassica oleracea semantics. We call it broccoli, since the head is green! However you classify it, Romanesco is a marvel that you have to see to believe. The beautiful, lime-green heads form whorls of intricate fractal patterns, making them look almost like an alien forest. And they’re tasty, if you can stand to cut them up!