Growing Broccoli

Posted On April 2, 2020

Broccoli is a sun-loving, cool-season crop that is best grown in the spring or fall. It’s also incredibly healthy and has been dubbed the “crown jewel of nutrition.” Here’s how to plant, grow, and harvest broccoli in the garden!

Broccoli is worth growing for its nutritional content alone. In many recipes broccoli is used for flavor and nutrition value. See broccoli salad with warm vinaigrette, or broccoli and spinach frittata. This cole crop is rich in vitamins and minerals, and is a good source of Vitamin A, potassium, folic acid, iron, and fiber. Learn more about its benefits here.

Once you harvest the main head of a broccoli plant, it will often keep producing smaller side shoots that can be enjoyed for months to come.

Planting

When to plant broccoli

Broccoli is cool-season crop, so it should be planted in early spring or late summer for the best results. High mid-summer temperatures will stunt its growth, so the goal is to get broccoli to mature before or after high temperatures are expected.
Broccoli seeds are capable of germinating in soil temperatures as low as 40°F (4°C), but warmer soil is preferred and will greatly speed up development.
For spring plantings, broccoli may be started indoors or outdoors a few weeks ahead of your last spring frost date:
Start seeds indoors 6 to 8 weeks before your last frost date.
Sow outdoors 2 to 3 weeks before your last frost date, or as soon as the soil can be worked.
For fall plantings (best in warm climates), sow seeds outdoors 85 to 100 days before the first fall frost, when soil and ambient temperatures are high. Or, start seeds in late May.

Choosing and preparing the planting site

Broccoli requires a site with exposure to full sun (6 to 8 hours per day). Lack of sunlight may produce thin, leggy plants and subpar heads.
Plant in a bed of moist, fertile soil that drains well.
Soil pH should be slightly acidic, between 6.0 and 7.0.
To increase fertility before you plant, in early spring, work in 2 to 4 inches of rich compost or a thin layer of manure. (Learn more about soil amendments and preparing soil for planting.)

How to plant broccoli

If starting outdoors, sow seeds ½ inch deep and 3 inches apart. Once seedlings reach a height of 2 to 3 inches, thin them so that plants are 12 to 20 inches apart.
If you started seeds indoors, plant transplants that are 4 to 6 weeks old (and have 4 or 5 leaves) outdoors, 12 to 20 inches apart, in holes slightly deeper than their container depth.
Space rows of broccoli 3 feet apart. (Closer spacing yields smaller main heads but more secondary heads.)
Water well.

Care

When to grow broccoli

Plants thrive outdoors in 65°F to 70°F (18° to 21°C) conditions.
Fertilize broccoli three weeks after transplanting seedlings into the garden. Use a low-nitrogen fertilizer.
Thin when plants reach 2 to 3 inches tall.
Provide consistent soil moisture with regular watering, especially in drought conditions. Water at least 1 to 1 ½ inches per week.
Do not get developing broccoli heads wet when watering, as it can encourage rot.
Roots are very shallow, so try not to disturb the plants. Suffocate weeds with mulch.
Mulch will also help to keep soil temperatures down.
Use row covers to minimize pests.
To promote the growth of a second head after the first has been harvested, maintain an active feeding and watering schedule.
If bottom, then top, leaves turn yellow, add blood meal.
Learn more about taking care of your broccoli plant.

Pest/Diseases

Aphids: Curling leaves may mean that the plant’s sap is being sucked by insects. Apply soapy water to all sides of leaves whenever you see aphids.
Cabbage loopers: Small holes on the leaves between the veins mean small green caterpillars are present. Look at the undersides of the leaves. Hand pick if the problem is small or control with Bacillus thuringiensis, a natural, bacterial pesticide. Use a floating row cover just after planting through harvest to prevent caterpillars.
Cabbage root maggots
Cabbageworms and other worm pests: Treat same as loopers.
Clubroot: Quickly wilting plants may be due to this fungus in the soil. The entire plant, including all roots and root tendrils, must be gently dug up and removed. If the roots are gnarled and misshapen, then clubroot is the problem. Act quickly to remove the plants so that the fungus doesn’t continue to live in the soil. Do not compost the plants. Raise the pH of your soil to above 7.2. You may need to sterilize your soil, too.
Downy Mildew: Yellow patches on leaves are usually caused by moist weather. Keep leaves as dry as possible with good air circulation. Buy resistant varieties.
White rust
Whiteflies
Nitrogen deficiency: If the bottom leaves turn yellow and the problem continues toward the top of the plant, the plants need a high nitrogen (but low phosphorus) fertilizer or blood meal. Blood meal is a quick nitrogen fix for yellowing leaves.

Harvest/Storage

When to harvest broccoli

Harvest broccoli in the morning, when the buds of the head are firm and tight, just before the heads flower.
If you do see yellow petals, harvest immediately, as the quality will decrease rapidly.
Cut heads from the plant, taking at least 6 inches of stem. Make a slanted cut on the stalk to allow water to slide away. (Water can pool and rot the center of a flat-cut stalk, runing the secondary heads.)
Most varieties have side-shoots that will continue to develop after the main head is harvested. You can harvest from one plant for many weeks, in some cases, from spring to fall, if your summer isn’t too hot.
Learn more tips on harvesting broccoli.

When to store broccoli

Store broccoli in the refrigerator for up to 5 days.
If you wash before storing, make sure to dry it thoroughly.
Broccoli can be blanched and frozen for up to one year.

Recommended Varieties

‘Green Goliath’ is heat-tolerant with giant heads and prolific side shoots.
‘Green Duke’ is heat tolerant and an early variety that’s especially good for Southern gardeners.
‘Green Magic’ is heat tolerant; freezes well.
‘Calabrese’ is an Italian heirloom with large heads and prolific side shoots that will mature for harvesting. Great for fall planting, too.
‘Flash’ is a fast-growing, heat-resistant hybrid with good side-shoot production once the central head is cut. Great for fall planting, too.
‘Paragon’ has extra-long spears; excellent for freezing.