Broccoli is a hardy cool-weather fall crop that’s a joy to grow in your vegetable garden. Full of Vitamin A, potassium, folic acid, iron, and fiber, a broccoli harvest is a nutrition powerhouse — and it’s not too difficult to grow either!
Broccoli, when grown properly, will grow to be about 18-36 inches tall with single or multiple flower heads of tiny green buds. It’s ready for harvesting and eating in between just 55 and 100 days.
We’ve compiled the complete guide to growing broccoli. It’s everything you need to know to grow, from seed to harvest, plus the most frequently asked questions and our favorite growing tips.
How Does Broccoli Grow?
Broccoli is a member of the Brassica oleracea family, a group of cruciferous vegetables that do well in partial shade. This family also includes Brussels sprouts, radishes, cabbage, cauliflower, and kohlrabi. Broccoli itself is a biennial grown as a cool-season annual.
Structurally, broccoli grows with a thick central stalk (sometimes multiple) and lots of hardy side shoot leaves. The central stalks of the broccoli is what we are most used to enjoying. It begins as a hearty head before turning into lots of tiny yellow flower buds. We typically eat it before the flowering process, so, when growing, you’ll want to time your harvest correctly.
When to Grow Broccoli
Broccoli needs to be grown so that it’s fully mature by the time temperatures average about 80° Fahrenheit.
During the grow, broccoli prefers temperatures between 45°F and 75°F. It can tolerate temperatures as low as 20° and a light frost.
Grow Pro Tip: Don’t allow your broccoli to freeze and avoid the heat! Too cold or too warm of weather will cause your broccoli to go to seed without forming heads.
To harvest in early spring/summer, start broccoli seeds indoors 5-6 weeks before the last frost. Transplant seedlings to the outdoors 2-3 weeks before the last frost in springs.
For a late autumn/early winter harvest, start seeds indoors in late summer. Then, sow transplants outside in autumn.
How to Grow Broccoli from Seed
To grow broccoli from seed, start your seeds indoors. Sow a half-inch deep and 3 inches apart in rich soil. Water well and let grow for 2-4 weeks.
Once your transplants have 4-5 true leaves, they’re ready to be moved outdoors. If your transplants turn out leggy or have crooked stems, plant up to the leaves so they won’t grow top-heavy.
Plant the seedlings 18-24 inches apart in town 24-36 inches apart. Water well to help settle into their home.
How to Grow Broccoli from Transplants
To avoid the most delicate stage of growing, buy transplants from a trusted buyer or Gardenuity. Plant 18 to 24 inches apart in rows 24 to 36 inches apart.
When replanting, take careful watch. Water thoroughly as the seedlings adjust to their new home.
How to Grow Broccoli in Containers
Growing broccoli in containers is a great alternative to garden beds — especially if you don’t have a backyard! All you need is a patio, balcony, or fire escape to grow successfully.
Find a container that you love (and that breathes/drains well) and plant! Find our complete guide to container gardening here.
A single head of broccoli will grow really well in an 8-inch container. To grow multiple heads, find larger containers and set them about 18 inches apart.
Gardenuity container garden kits come with everything you need to grow broccoli in a container garden.
Grow Pro Tip: Container gardening is a good option for broccoli because of its disdain for the heat. Move to the shade on hot and long days to keep the broccoli tasting good.
How to Care for Your Broccoli Garden
Broccoli grows best compost-rich, well-drained soil. Ideally, the pH should be between 6.0 and 6.8.
Organic matter and the right pH make sure that micronutrients like boron are in the soil. Without enough boron, broccoli will develop hollow stems; too much is toxic to broccoli.
Mulch the ground generously as the weather warms — it will keep the soil moist and cool.
Broccoli likes partial shade, but can also tolerate full sun. Typically, you should give your veggies between 4-8 hours of sunlight per day. The shade will help delay flowering, leading to a larger harvesting window. If you are in an area without a lot of shade, consider using a row cover.
Broccoli does well in cooler climates. Try to time your growing season to begin in early spring or before the fall frost, as it is not very heat tolerant but also does not always withstand cold.
For best results, keep your broccoli garden’s soil moist. Broccoli needs about 1-1.5 inches of water per week.
When watering, water at the base — NOT the central heads. Wetting the heads will encourage rot and invite unwanted pests such as aphids, maggots, or flea beetles.
As your broccoli nears maturity, decrease the watering slightly. Too much soil moisture can lead to issues like mildew.
Broccoli could be infested by aphids, caterpillars, cutworms, cabbage loopers, or imported cabbage worms.
To avoid, handpick pests off the plant and spray with organic, natural pesticides.
Broccoli Growing Stages
Broccoli has 5 fairly distinct growing stages. Being able to identify each growing stage as it occurs will help you as you grow broccoli — especially in knowing when to harvest.
The first stage is seed development. Broccoli takes about 1-2 weeks to germinate. While in this stage, keep seeds indoors and in a preferably warm area — around 80° F.
Once the seeds have germinated, you have 3-4 weeks of seedlings development. Here, they develop roots and their first leaves. Once you see the seedling emerge from the soil, reduce the temperature to 60° – 65° F. Keep indoors until 4 weeks old.
Sow seeds and transfer the young plants outdoors. In this stage, broccoli develops a stalk and mature leaves. Then, the flowering top we associate with broccoli. For the next 55 – 65 days, they will continue to mature. Water regularly according to the care instructions above.
Once the broccoli has developed the tight green buds you associate with broccoli at the grocery store, your broccoli is ready to harvest. The heads are usually best harvested when 6-8 inches across and compact. Harvest according to the instructions below.
The final stage of a broccoli plant is to bolt, or go to seed. This is when the tight green buds bloom and produce yellow flowers. Once this has occurred, your broccoli is no longer edible. If you let your broccoli go to seed, collect the seed for next year!
How to Prevent Broccoli Bolting
Eventually, all plants bolt or flower — it’s part of the life cycle!
When broccoli flowers, however, the plant becomes inedible.
While you can’t prevent bolting, you can slow broccoli from flowering by keeping it cool. Warm weather speeds up the flowering process for broccoli. Use mulch, regular watering, and row covers to keep your broccoli cool.
Additionally, harvesting on time and frequently will help to prevent your broccoli from going to seed!
How to Harvest Broccoli
If growing from seeds, your broccoli will be ready to harvest in about 100-150 days. If growing from transplants, your broccoli will be ready to harvest in 55-80 days.
Harvest when the buds are green and tight. They will look like ‘trees’ — just like you see in the grocery store although the heads may be generally smaller. The buds should be tightly closed. If you see the buds beginning to open, harvest immediately!
Opening buds mean they’re about to bloom into the yellow flowers, which makes broccoli inedible.
When harvesting, take a sharp knife to the main head, leaving about 5-6 inches of stem. Cut the stalk at a slant so the water will slide off — water can pool and rot the center of the stalk, ruining any secondary heads.
Try to harvest in the morning before the plant heats up. This will ensure the best taste.
Secondary heads will continue to mature; encourage growth by adding nitrogen-rich fertilizer around the base. Then, once secondary shoots are mature, repeat the harvesting process with them.
How to Store Broccoli
Store your freshly harvested broccoli in the fridge for about a week. Alternatively, blanch and then freeze for up to 3 months.
Broccoli Gardening FAQ’s
When you begin to see yellow flowers, you have waited too long to harvest. The yellow flowers make the broccoli inedible. Harvest earlier, when the buds are tightly closed and green.
Broccoli lasts about 1 week in the fridge, depending. To keep for longer, blanch it and then store in the freezer.
Broccoli rabe is actually completely unrelated to broccoli — it’s an entirely different vegetable and in an entirely different family.
Broccoli rabe has a milder taste than broccoli, with smaller florets and darker, edible leaves.
Yes! Believe it or not, broccoli was bred more than 2,000 years ago by Italian farmers. They bred several types of cabbage to create what we now know as broccoli.
Yes, broccoli is easy to grow! It’s a great vegetable for new gardeners.
Broccoli takes between 55 and 100 days to reach harvestable maturity.
Broccoli should be grown with full to partial sun in a cooler season.
Plant broccoli in the spring, late February or early March, depending on your climate.
Broccoli heads will be dark green and semi-solid when they are ready to be harvested. If they start developing yellow flowers, you have waited too long.
Wait until the plant is fully mature, between 55 and 100 days.
Broccoli is ready to harvest when the head is made up of tightly packed, dark green buds.
If growing in raised beds, you’ll need to plant your broccoli between 15 and 18 inches apart.
Broccoli likes well-draining soil with a pH between 6 and 6.8.
If you need any additional help or information, reach out to the Gardenuity Grow Pros for expert gardening advice.
Begin your broccoli garden now with Gardenuity garden kits!