Broccoli is a stout, thick-stemmed plant in the Brassicaceae family, which also includes cabbage, kale, and Brussels sprouts. Large, blue-gray leaves are leathery and oblong, arranged around an upright trunk-like structure that supports a flowering head. The part we eat is actually the buds of the broccoli flower. If left unharvested, the broccoli head would open into small greenish-yellow flowers. Although most broccoli is green, there are also some delicious and beautiful purple varieties.
Broccoli has a moderate growth rate. It is typically planted in the early to mid-spring for an early summer harvest. And in warm climates, a late summer planting can yield a fall harvest.
|Botanical Name||Brassica oleracea var. italica|
|Plant Type||Biennial, annual, vegetable|
|Size||18–30 in. tall, 12–24 in. wide|
|Sun Exposure||Full sun|
|Soil Type||Moist, loamy, well-drained|
|Soil pH||Acidic, neutral|
|Hardiness Zones||2–11 (USDA)|
|Native Area||Mediterranean, Asia|
How to Plant Broccoli
When to Plant
In the spring, plant seeds outdoors roughly two to three weeks prior to your area’s projected last frost date. You also can start seeds indoors approximately six to eight weeks prior to the last frost date for a jump on the growing season.
In the fall, plant seeds in the garden approximately 85 to 100 days prior to your area’s projected first fall frost date.
Selecting a Planting Site
Pick a sunny spot that has good soil drainage for your broccoli. Container growth is an option if you don’t have a suitable garden site.
Some good companion plants for broccoli include dill, rosemary, cucumber, and celery. However, there are some plants that broccoli prefers not to be near in part because they’re heavy feeders, including asparagus and sweet corn.
Spacing, Depth, and Support
Plant seeds roughly 1/2 inch deep and a few inches apart. Rows should be 12 to 20 inches apart. Likewise, thin seedlings to around 12 to 20 inches apart. A support structure shouldn’t be necessary.
Broccoli Plant Care
Broccoli grows best in a spot with full sun, meaning at least six hours of direct sunlight on most days. However, in very hot climates, partial shade from afternoon sun might be necessary to prevent bolting, or the plant flowering and going to seed.
Broccoli prefers a rich loamy soil with lots of organic matter. Good drainage also is a must. The soil pH should be slightly acidic to neutral.
Keep the soil moist but never soggy. Also, water from the base of the plant, not overhead as this can promote rot. Around 1 to 1.5 inches of water per week should suffice. A layer of mulch can help to retain soil moisture.
Temperature and Humidity
Broccoli does best in temperatures between 65 and 70 degrees Fahrenheit. Temperatures that are too hot—above roughly 80 degrees Fahrenheit—can cause bolting. Humidity typically isn’t a factor as long as there’s optimal soil moisture and good air circulation around plants.
Mix compost into the soil before planting to improve its nutrient content and drainage. Then, fertilize using an organic low-nitrogen fertilizer starting a few weeks after seedlings emerge. Repeat fertilization throughout the growing season, following label instructions.
As broccoli is typically harvested before it blooms, pollination isn't an issue for most gardeners. Bees and other insects help to pollinate the flowers when they do bloom.
Types of Broccoli
There are many varieties of broccoli that range in appearance, growth rate, and more, including:
- ‘Calabrese’: This variety features large heads and does well with fall plantings.
- ‘Green Magic’: This is a heat-tolerant variety.
- ‘Green Goliath’: This also has good heat tolerance and grows very large heads.
- ‘Flash’: This variety is known for its relatively quick growth rate.
Broccoli vs. Broccoli Rabe
Broccoli and broccoli rabe (Brassica rapa) may share a common name; however, they are two different species (though still relatives). Broccoli rabe, or rapini, grows buds that look like those of broccoli. But it doesn’t form the large dense heads that broccoli does. Instead, it leans more toward being a leafy green, and people generally eat the stems, leaves, and buds.
Most broccoli varieties are ready to harvest once their heads reach the size of a large fist. If you wait too long, the buds will open. You can still eat the stalks at that point, but they will be tougher.
The best time to harvest is in the morning, as the heads and stalks will be at their firmest. Cut roughly 6 inches of stalk with the heads. Make an angled cut, so water doesn’t collect on the cut surface and rot any side shoots that are still growing.
Wash the broccoli before storing in the refrigerator, where it should keep for around five days. It also can be blanched and frozen for roughly a year.
How to Grow Broccoli in Pots
Growing broccoli in a container can help you better control the soil, light, and moisture conditions. Plus, containers can sometimes protect plants from garden pests and diseases.
Choose a container that’s at least a foot wide and deep per broccoli plant. Make sure it has drainage holes. Unglazed clay is an ideal material because it will allow excess soil moisture to evaporate through its walls, helping to prevent overwatering. Also, opt for a light-color container, as dark colors can cause the soil (and roots) to get too warm.
Pruning generally isn't necessary for broccoli plants. However, you should promptly remove any damaged or diseased stems before they can weaken the whole plant.
As long as you don’t have any other members of the Brassica genus in the vicinity of your broccoli plants that could cross-pollinate, you can save seeds to propagate your broccoli. This is a cost-effective and simple way to create more plants, and it allows you to essentially clone varieties that you liked for their flavor, production, and more. You’ll save seeds typically in the summer or fall, depending on when you’ve planted your broccoli. Here’s how:
- Let the broccoli grow past the point of when you would normally harvest it. Eventually, small yellow flowers will appear and give way to seed pods.
- Once the seed pods turn from green to tan and appear dry, the seeds should be mature. At that point, cut down the entire plant and hang it in a warm, dry spot with good air circulation for a couple weeks so that the seeds continue drying.
- Once the seed pods have fully dried, gently cut them from the plant. Crumble them over a white cloth, so you can easily spot and separate the seeds from the chaff.
- Store the seeds in an envelope or airtight container labeled with the date. They should be viable for about five years.
How to Grow Broccoli From Seed
Broccoli seeds need soil temperatures of at least 40 degrees Fahrenheit to germinate. To start them in a container, use a shallow tray filled with moist seed-starter mix. Put the container in bright, indirect light in a spot that ideally remains between 45 and 85 degrees Fahrenheit. Keep the soil moist but not soggy, and you should see germination within a week. Harden off the seedlings before planting them outside.
Potting and Repotting Broccoli
A quality organic vegetable potting mix should be sufficient for potting broccoli. Just make sure it's rich in organic matter and drains well. Repotting shouldn't be necessary, as it's best to plant broccoli in a container that can accommodate its mature size to avoid disturbing the roots.
As broccoli is generally grown as an annual, no overwintering maintenance will be necessary. If you're trying for a fall harvest, just make sure to plant early enough to beat the freezing temperatures.
Common Pests and Plant Diseases
Broccoli is susceptible to the same pests and diseases as other members of the cabbage family. The most common pests include cabbage loopers, cabbageworms, cabbage root maggots, and aphids. Row covers can help to prevent infestations.
Common diseases include blackleg, black rot, and clubroot. Disease control is best achieved by rotating where you plant your broccoli each year, as well as making sure it's growing in proper conditions.
Is broccoli easy to grow?
Broccoli is relatively easy to grow as long as you time its planting to prevent it from being exposed to high heat. You also must make sure it has sufficient water and nutrients in the soil
How long does it take to grow broccoli?
Broccoli takes around 100 days on average to go from seed to harvest. However, growth rate can differ by variety.
Does broccoli come back every year?
Broccoli is technically a biennial, completing its lifecycle in two growing seasons. However, most people grow it as an annual to harvest before it flowers and goes to seed.