How to Grow Broccoli in your Home Garden
The secret to the best-tasting broccoli is in the seasoning–not the spices, mind you, but the time of year. Broccoli that matures during cool weather produces healthy heads that are sweeter tasting than those you pick at any other time. Grow it this fall, and you will enjoy the most tender and flavorful broccoli you’ve ever eaten–long after the summer garden is a memory.
Broccoli grows best in fall because spring conditions may be unpredictable. Long, cool springs, for example, cause young transplants to form small, early heads; if temperatures heat up early in spring, heat-stressed broccoli opens its flower buds prematurely. And high temperatures as broccoli matures can cause bitter, loose heads to form, leaving you with smaller and less tasty florets. In fall, broccoli produces bigger and tastier heads, as plants mature during cooler weather.
Broccoli Growing Guide
When to Plant Broccoli
You can easily figure the perfect time to plant broccoli seeds this fall. If you want to sow seeds directly in the garden, do so about 85 to 100 days before the average first fall frost in your area, which happens in mid to late summer in most places. If you prefer to grow from transplants, figure the date for getting your plants in the ground by adding 10 days to the “days to maturity” for the variety you’re growing, and then counting backward from your expected first fall frost date.
Broccoli grows best in full sun and where the soil is slightly acidic (pH between 6.0 and 6.8), fertile, and well-drained, yet consistently moist and rich in organic matter. The right pH and the organic matter help ensure that nutrients, particularly essential micronutrients like boron, are readily available. (A boron deficiency can cause broccoli to develop hollow stems, but adding too much is toxic to plants, so a soil test is essential.)
Fall broccoli has specific spacing requirements. If you’re gardening intensively in a raised bed, space your plants 15 to 18 inches apart; for gardening in rows, set the transplants 18 to 24 inches apart within the row and space the rows 24 to 36 inches apart. Be sure to set transplants slightly deeper in the ground than they were in the pot.
Keep Them Nourished
Broccoli is a moderately heavy feeder, so work in 2 to 4 inches of rich compost or a thin layer of well-aged manure before planting. Rabbit manure is a personal favorite, though most any aged manure or compost produces big and tasty heads. After you’ve harvested a plant’s central head, you can encourage extended side-shoot production by scratching a little nitrogen-rich fertilizer such as fish meal or aged manure into the soil around its base (this is known as side-dressing). The best time to side-dress sprouting types that have overwintered is in late winter or early spring when growth resumes.
Shelter from Cold
Freezing temperatures can cause a chilling injury that turns buds purple and sometimes softens heads, though they are still good to eat. “I’ve had broccoli freeze solid, and when it thawed out it was fine,” says Atina Diffley, co-owner of Gardens of Eagan Organic Farm, in Minnesota. Just don’t let heads freeze and thaw repeatedly.
Offer cold-weather protection with floating row covers, which provide an additional 4 degrees to 8 degrees F worth of warmth, shielding harvests from heavy freezes and extending the season by up to four weeks. Or cover broccoli with tunnels or a cold frame, which can boost daytime temperatures by 10 degrees to 30 degrees F.
Protect Against Pests Control
Row covers provide some protection from pest insects, but the best protection is to grow healthy plants, and that begins with healthy soil, says Colby Eierman, director of gardens at COPIA: The American Center for Wine, Food & the Arts, in Napa, California. Insect pests are generally less prevalent in fall than in spring. But if your broccoli does suffer an infestation of destructive caterpillar pests such as cabbage loopers, you can control them with Bacillus thuringiensis var. kurstaki, a naturally occurring bacteria that stop the pests from chewing but is harmless to beneficial insects.
For best flavor, harvest broccoli heads while the buds are just starting to swell but before the yellow petals start to show. Keep an eye on the head, for when it begins to spread open, the individual buds start to flower. Harvest the central head by cutting the stalk at a slant, about 5 to 8 inches below the head. This encourages side-shoot production for continued harvests. Diffley says it’s important to harvest broccoli in the morning before the plants heat up because broccoli has a really high respiration rate. “Once the heat sets in, you need to cool it down quickly, or it’s not going to hold up well and taste as it should,” she says.
Now that you’re set to grow the best-tasting broccoli ever, be sure to keep that flavor intact by not overcooking–broccoli is best when cooked until tender-crisp and still bright in color. In fact, Eierman says the chef at COPIA has a simple way of letting the flavor of broccoli shine: The florets are blanched and then shocked in an ice bath, then quickly stir-fried in olive oil. Of course, the best dishes begin with homegrown broccoli that’s perfectly seasoned.
Perfect Companions for Broccoli
Plants that Help Broccoli Grow Better:
- Celery, potatoes, and onions improve the flavor of broccoli when planted nearby.
- Aromatic herbs, such as rosemary, sage, dill, and mint, help broccoli by repelling insect pests.
- Plants that require little calcium, such as beets, nasturtiums, and marigolds are good companions because they grow happily with broccoli–a notorious calcium hog.
Plants Helped by Broccoli:
Plants to Avoid Planting Near Broccoli:
The Brassica family of vegetables includes cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower, cabbage, and kale. They contain phytochemicals called isothiocyanates including sulphorophanes, which may induce enzymes that reduce inflammation and detoxify carcinogens.
They’re also rich in fiber, vitamins, and minerals (while being low in calories). So far, research shows this combination of nutrients and phytonutrients means cruciferous vegetables may prevent cancer and help soothe airway inflammation. The sulphorophanes may also help reduce the risk of cardiovascular disease and inhibit H. pylori, bacteria that causes ulcers.
The sulphorophanes are more concentrated in young plants, so broccoli sprouts contain larger amounts compared to mature broccoli plants, about 20 percent to 50 percent more per ounce. You can easily add broccoli sprouts to your diet by sprinkling a handful of sprouts on top of a salad or stuff them into a wrap or sandwich. They have a flavor similar to radishes, slightly peppery.
You can buy sulphorophane glucosinolate supplements, but getting them from your diet is much better. The cruciferous vegetables contain many other nutrients and phytochemicals such as indoles that your body needs, plus it isn’t completely clear how well the sulphorophane glucosinolates work in isolation. The sulphorophanes may work best in harmony with other phytochemicals found in broccoli sprouts and other cruciferous vegetables.
- Johnson IT. “Glucosinolates: bioavailability and importance to health.” Int J Vitam Nutr Res. 2002 Jan;72(1):26-31.
- Blomhoff R. “Dietary antioxidants and cardiovascular disease.” Curr Opin Lipidol. 2005 Feb;16(1):47-54.
- Riedl MA, Saxon A, Diaz-Sanchez D. “Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway.” Clin Immunol. 2009 Mar;130(3):244-51.
- Nestle M. “Broccoli sprouts as inducers of carcinogen-detoxifying enzyme systems: clinical, dietary, and policy implications.” Proc Natl Acad Sci U S A. 1997 Oct 14;94(21):11149-51.