How to Grow Broccoli: A Comprehensive Guide from Seed to Harvest
Whether you’re a seasoned gardener or just beginning, this guide is packed with tips and tricks to guide you through the entire process of growing broccoli from seed.
Watch the video version of this grow guide on my YouTube channel:
Cultivar Selection
Cultivar selection is crucial when growing broccoli. There are some characteristics to keep in mind when shopping for broccoli seeds.
Heading vs Non-heading or Sprouting Broccoli
1. Heading Broccoli: This type forms one large head in the middle of the plant. After harvesting this main head, most varieties continue to produce smaller side shoots.
2. Sprouting Broccoli: This type doesn’t form a large central head but produces many side shoots.
Broccoli Color Options
While the standard grocery store broccoli is green, other varieties such as the unique Purple Peacock broccoli and neon green Romanesco broccoli are worth growing for their special colors and textures.
Broccoli Cultivar Examples
Romanesco: A hybrid between broccoli and cauliflower, known for its fractal geometric shape.
Godzilla: A hybrid that can grow heads up to six or seven inches across.
Piracicaba Brazilian Sprouting Broccoli: Noted for its heat tolerance, making it an excellent choice for gardeners in warmer climates.
Differences In Maturity Dates
Varieties also differ in their maturity dates. For example, De Cicco matures in about 70 days, producing smaller heads but consistently providing side shoots. Early Purple Sprouting starts producing in 59 days.
How To Sow Broccoli Seeds
Broccoli needs a 8 to 12 week growing period from seed, to be big enough to transplant.
When To Sow Broccoli Seeds
- Cold Climates - If your area gets snow or the ground freezes - sow broccoli seeds indoors, 12 weeks before your last average spring frost date and then plant them outside.
- Hot Climates - If you don't get any snow and have mild winters (most likely Southern parts of the USA zones 8 and up), it is best to plant them in fall so they grow during the coolest parts of the year. The target date for transplanting broccoli into the garden is the first month in fall where the average maximum high temperature is at 85F or below. Backtrack 10-12 weeks prior to this month to know when to sow seeds indoors. Check out this website: www.plantmaps.com to find your monthly average high temperature.
How To Sow Broccoli Seeds
- Sow seeds indoors because it will either be too hot or too cold.
- Fill some 4 inch pots (find HERE) with sterile seed starting mix.
- Sow 3 seeds per 4 inch pot, and cover with 1/4 inch of soil. Water in.
- Once the seeds germinate they will require light. Setup supplemental light by using 5000K or higher shop lights or grow lights. I really like Mars Hydro 3x3 grow lights (find it HERE). Zip tie the lights to a mini greenhouse (find the greenhouse I like to use HERE), or shelving unit. Turn the lights on when you wake up in the morning and turn them off in the evening.
- Start fertilizing once the seedlings grow their first set of true leaves. Use a liquid fertilizer and mix at half strength of whatever the directions say. I really like Fox Farms Grow Big (find it HERE). Fertilize weekly to grow big and healthy transplants.
- In about 10-12 weeks, they should be ready to transplant.
Ideal Growing Conditions For Broccoli
- Sun - Broccoli plants need full sun. In Florida, it is best to plant them in a spot that gets a lot of direct morning sun with some afternoon shade.
- Soil - Broccoli plants are very nutrient hungry. Plant is soil rich with organic matter.
- Water - Broccoli plants need moderate amounts of water but not too much water that the roots stay wet. This will cause root rot.
How To Transplant Broccoli
Seedlings are ready to transplant once their roots hit the bottom of the container. Choose a location with full sun and ensure your soil is rich in organic matter. Add some organic granular fertilizer like Espoma Garden Tone and blood meal into the planting hole before transplanting.
- Plant broccoli at least 2FT apart. If you're growing one of the giant cultivars, give them even more space like 4FT apart.
- If growing broccoli in a grow bag - plant 1 broccoli plant for every 10 gallons of grow bag. I like these grow bags from Amazon HERE.
- Add fertilizer into the planting hole to give seedlings an extra boost. I really like Espoma Garden Tone (find it HERE).
- If you're in nematode prone areas, add a handful of crab meal. Find crab meal HERE.
- Anything that is grown to eat its leaves benefits from adding some blood meal (high nitrogen) into the planting hole too. Find blood meal HERE.
- Mix these amendments into the soil a little but before inserting the broccoli seedling.
- Fill and pat down the soil. Water it in.
In a few weeks, you should notice new growth on your broccoli seedlings. Now it is time to start fertilizing. Sprinkle 1/8 cup of an organic granular fertilizer like Espoma Garden Tone (find it HERE) at the base of each plant every 7 to 10 days to keep the nutrient supply consistent. Follow the package directions if using a synthetic fertilizer.
How To Treat For Aphids & Worms On Broccoli Plants
The most common pest that I see on my broccoli plants are aphids. Spray with neem oil or organic insecticidal soap. The second most common pest I get with anything in the brassicas family is worms or caterpillars. If you notice chewed up leaves, and small orange, green, or black balls, its some sort of worm. If its a small infestation you can easily hand pick them off, but for larger infestations spray with BT. Find the BT spray I use HERE.
Pruning & Watering Your Broccoli Plants
Remove any old, dead, dying, yellowing, diseased or pest infested leaves. Also, water at the base of the plants to avoid wetting the leaves. Pruning and watering at the base will help slow down the spread of the pathogens that cause disease. Spray with one cup hydrogen peroxide per gallon of water to clean and disinfect the leaves if they get some sort of disease.
How To Harvest Broccoli
The first sign that a head of broccoli is ready to harvest is when you notice the small flower buds start separating. Use scissors to cut the head just above the first leaf node to encourage the plant to produce side shoots. These side shoots should also be harvested regularly to maintain production.