How to Help Broccoli Form Full Heads

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Photo by Adobe Stock/Paleka
Broccoli is a heavy feeder, so be sure to mix in some compost at planting time.

Question: Why does my broccoli only produce tiny heads, then go to flower so quickly? It isn’t even growing a big enough head to be considered a rabe.— Sherri Jordan

Answer: Broccoli can be surprisingly finicky. To thrive, the plant requires rich, well-drained soil; a stretch of cool weather; and at least six hours of full sun daily. Try these techniques to give broccoli the boost it needs to produce good-sized heads.

Avoid summer heat. It’s typically recommended that you start broccoli indoors 4 to 6 weeks before your last spring frost and transplant seedlings when they’re 4 weeks old. But if your region has short springs, the plants likely won’t have enough cool weather to form heads. Broccoli may grow better as a fall crop in your area.

Fertilize and water. Broccoli is a heavy feeder. Make sure your soil is fertile enough by mixing in at least 1 inch of compost at planting time. You can also apply a high-nitrogen organic fertilizer, such as alfalfa meal or composted poultry manure, every few weeks. Provide about an inch of water weekly.

Mulch heavily. Keep the soil from overheating by mulching with 2 to 3 inches of straw or grass clippings. (Ignore this advice if you live in a climate troubled by slugs.)

Experiment. Play with cultivars, planting dates, fertilizers, and even locations in your garden. Grow several broccoli cultivars each season, taking notes on how each performs in wet, dry, hot, or cold weather. If your garden is located in a warm region, try heat-tolerant cultivars, such as ‘Imperial’ and ‘Green Magic.’

And, finally, accept that your garden may never be able to produce heads as large as commercial farms can. A primary head measuring 4 to 6 inches in diameter, followed by 1- to 2-inch secondary heads, may be the best your broccoli has to offer. It’ll still taste great.

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Mother Earth Gardener
Mother Earth Gardener
Expert advice on all aspects of growing.