How to Grow Broccoli from Seed

Learn to grow broccoli from seed with our step-by-step guide, and enjoy a bountiful harvest in your own garden during the cooler months.

Broccoli is a cool weather crop that grows quickly from seed, producing edible stalks and flower heads in as little as 50 to 60 days after transplanting. Many varieties keep producing new flowering shoots for several weeks or longer, undeterred by fall frost. In fact, a touch of frost can enhance the flavor!

If you want to try growing broccoli from seed, you've come to the right place. I'll walk you through the different varieties and when to plant them, as well as some tips and tricks for producing a bountiful harvest.

Let's get growing!

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Broccoli Varieties

Broccoli comes in heading and sprouting varieties. Most everyone is familiar with the heading types with their tight bunches of buds. Sprouting varieties form multiple shoots with much smaller, loose flower heads, often with outstanding tenderness and flavor.

For spring planting, choose varieties with shorter maturity dates of 50 to 60 days. If you’re planting in the fall, pick types with a more extended maturation date of 60 to 85 days.

Some popular broccoli varieties include:

• ‘DiCicco’ is an excellent choice for the home garden because it produces several medium-sized heads over an extended time, starting 50 days after transplanting.  
• ‘Castle Dome’ can be planted later in the season than most due to its heat tolerance. 
• ‘Calabrese’ is an heirloom from Italy with large, bright green heads. 
• ‘Purple Sprouting’ grows well in cold temperatures, producing multiple vibrant-purple shoots with small flower heads. The purple color turns green when cooked. 
• ‘Romanesco’ heads have a highly unusual, light-green, spiral shape and bolt quickly in warm weather. 

How to Plant Broccoli Seeds

If you aim for spring planting, start broccoli seeds inside in April, and start seeds indoors or direct sow in mid to late July for a fall planting.

• Plant the seeds in a sterile, soilless seed starting mix to avoid damping off. 
• Plant broccoli seeds about ½ inch deep and firm the soil over them. 
• Keep the containers at 70 to 75°F and evenly moist until germination. A seedling heat mat can help keep temperatures consistent.
• Move the trays into bright light or under grow lights after the seedlings appear in 7 to 14 days. 
• Fertilize the seedlings with a half-strength fertilizer solution once or twice a week after the first set of true leaves appears. 
• Harden the plants off before transplanting them four to five weeks after sprouting.

If you direct sow broccoli in summer, plant the seeds about 1 to 1 ½ feet apart in small groups and thin them to the best plant about two to three weeks after germination. Also, keep the seed bed evenly moist while the seeds sprout. 

Planting Broccoli in the Garden

Broccoli thrives in cool weather when temperatures are in the 60s. Plant it in soil that drains readily but does not dry out quickly. The best way to achieve this balance is by incorporating abundant high-quality compost or aged manure into the ground before planting. Compost and aged manure also provides a good dose of nutrients that broccoli needs to grow. 

Space the plants 12 to 18 inches apart in the rows, with 24 to 36 inches between rows. Plant the seedlings to the same depth as they are in the containers. When the plants are about 6 inches tall, side-dress them with a high-nitrogen fertilizer to encourage rapid growth.

Water the plants frequently because water stress can adversely affect the flavor. Add drip irrigation when possible to water straight at the roots.

Consider adding these companion plants for broccoli to deter pests and get the best use out of your soil's nutrients. You can learn more about companion planting here!

Caring for and Harvesting Broccoli

Keeping broccoli watered as it grows is key to harvesting flavorful heads. Mulching around the plants helps to retain moisture and keeps weeds down. 

Consider using a floating row cover to protect broccoli plants from pests. Aphids are a common pest of broccoli, but it’s easy to get rid of them using a firm jet of water from a hose. 

Harvest the heads when the flower buds are tightly closed as the plants reach their days to maturity for the variety you’re growing.

Cut each bunch free from the plant with a sharp knife, leaving the rest of the plant in place to produce side shoots or more leaves if you enjoy using them. The shoots that appear later are smaller but still taste great as long as you keep watering. 

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Growing broccoli from seed is a rewarding journey that leads to a delicious, nutritious harvest. With patience and a bit of care, you'll soon be feasting on your very own homegrown greens!