Broccoli Know-How (cont)
By: Charlie Nardozzi
Soil and Nutrients
All broccolis are heavy feeders. Before planting standard varieties, mix into your soil 2 cubic feet of aged manure or 3 pounds of a 5-10-10 fertilizer per 100 square feet. Sidedress with a pound of blood meal per 100-square-foot area when the transplants are about 6 inches tall. Broccoli is sensitive to some nutrient deficiencies -- especially boron (a common deficiency of coastal plain soils from New Jersey to Louisiana). Without adequate boron, plants develop small, mouse-ear-sized top leaves and hollow stems. If your soil tests low in boron, apply 1/2 tablespoon of borax mixed with compost over 100 square feet of garden.
Space plants 18 inches apart for large-sized heads. For better overall production, but smaller heads, space plants 12 inches apart. Mulch with a 4- to 6-inch-thick layer of straw to keep the soil cool and moist.
Insects and Other Pests
Summer insects can quickly kill a young broccoli plant. To control the most devastating ones (imported cabbageworm, cabbage looper, harlequin bugs, and cabbage maggots), cover broccoli transplants with a lightweight row cover, such as Agrofabric Pro-10. Leave it on throughout the season. The cover will let in light, air, and water, but unlike traditional row covers, it won't increase the temperature by more than 5oF. More important, the cover will prevent harlequin bugs from feeding and the adult forms of these other cabbage pests from laying eggs on the plants.
If you prefer not to use row covers, spraying with Bt will control any larvae, and pyrethrin will control harlequin bugs. Spray when you first see signs of insect damage. Place tar paper mats around young broccoli transplants to stop the cabbage maggot fly from laying eggs.
Here are the broccoli varieties I recommend for a fall or early spring harvest. It's based on discussions with gardeners and researchers throughout the United States, as well as my own experience here in Vermont. Information included is whether the variety is hybrid or open-pollinated (you can save your own seeds from the latter), the days to maturity from transplant (so you can mix early, midseason, and late varieties to extend harvest), and the variety's genetic ancestry, which indicates cold tolerance.
- 'Arcadia' (hybrid, 63 days). A large, late-maturing variety with good disease and cold tolerance; southern European.
- 'Calabrese' (open-pollinated, 58 days). An Italian heirloom sprouting type that produces lots of small (3- to 5-inch) heads over a long period; southern European.
- 'DeCicco' (open-pollinated, 48 days). A very early maturing sprouting type similar to 'Calabrese' but with larger heads; southern European.
- George's Favorite Blend (hybrid, 60-70 days). A blend of early, midseason, and late-maturing varieties in one packet; southern European.
- 'Green Valiant' (hybrid, 59 days). A compact midseason variety with good side shoot production. It's also one of the most cold tolerant of the southern European varieties. Needs high fertility to produce well.
- 'Marathon' (hybrid, 68 days). The number one broccoli variety grown in the world; often planted as a fall and winter crop. It's late maturing, produces uniform 6-inch-diameter heads, withstands cool conditions, and has good side shoot production; southern European.
- 'Packman' (hybrid, 50 days). An early, fast-maturing variety - good if you're late starting a fall crop; southern European.
- 'Premium Crop' (hybrid, 64 days). A midseason variety that produces large (9-inch) heads and has disease and heat tolerance; southern European.
- 'Purple-Sprouting' (open-pollinated, 220-250 days). An overwintering type that produce large yields of open purple heads in early spring. Also available as a white sprouting type. NG test gardeners report reliable production in zone 7b; northern European.
- 'Spring Green Mix' (open pollinated, 210 days). An overwintering mix of super hardy broccolis that produce large, 6- to 8-inch heads; northern European.
- 'Thompson 92' (open-pollinated, 70 days). A large-headed, late-season crop that matures over several weeks; southern European.
- 'Umpqua' (open-pollinated, 55 days). A midseason variety with a domed head and good side shoot production; southern European.
- Walcherin cauliflowers (open-pollinated 210-270 days). A series of northern European, overwintering cauliflowers from Holland that are technically white-headed broccolis. Individual varieties have similar characteristics, but mature at different times. NG tested 'Fleurly', 'Galleon', and 'Maystar'; 'Maystar' was preferred.
- 'Waltham 29' (open-pollinated, 75 days). A late-maturing heirloom known for its cold tolerance and abundant side shoot production; southern European.