It’s best to harvest broccoli in the cool of the morning

September 7, 2016

The 21-foot thick dome of the Pantheon in Rome isn’t made of stone but rather from Roman concrete, or Opus caementicium. This mixture of quicklime, pozzolana and an aggregate of pumice seems to hold up better than many modern concretes. Besides giving us concrete, and an inscrutable system of Roman numerals, the Romans gave us broccoli, a crop developed before the 6th century BC. Indeed, our word broccoli has its roots in the Italian plural of broccolo, meaning “the flowering crest of a cabbage.”

Broccoli is high in vitamin C and vitamin K, as well as containing potassium and iron. Broccoli also has more protein than most other vegetables.You can eat broccoli raw or cooked, though gentle steaming preserves the most nutrients. Research at Johns Hopkins University School of Medicine shows that the sulforaphane found in broccoli is quite effective in destroying helicobacter pylori, a bacterium that causes stomach ulcers. 

Broccoli is a great fall crop because its flavor is actually better after a few light frosts. Space fall broccoli transplants 18 to 24 inches apart within each row, with a good 24 to 36 inches between the rows. Set the transplants a little deeper in the soil than they were in the flats. 

Broccoli (Brassica oleracea var. botrytis) is a moderately heavy feeder that benefits from a rich garden soil. You can add compost or well-aged manure if your soil is poor. Keep your broccoli well watered and apply a mulch of grass clippings or straw to keep the soil cool and moist. Broccoli does best grown in full sun or light shade. It prefers a slightly acidic soil with a pH between 6.0 and 6.8. Proper soil pH allows the plants to absorb needed nutrients, especially micro-nutrients such as boron. If your broccoli develops hollow stalks it may be from a boron deficiency. 

Always harvest your broccoli before the flowers open. If you see tiny yellow flowers, your plants have matured, and even though still edible, your broccoli will not be as crisp and mild tasting. 

Because broccoli has a very high respiration rate, it’s best to harvest your broccoli in the cool of the morning. Cut the heads off with about six inches of the stem attached. Your plants will send up many smaller sideshoots with tiny broccoli heads for a later harvest. If winter is mild the plants can even survive until spring. 

Broccoli transplants are usually available from local garden centers. Look for heirlooms such as Calabrese that will produce large, dark-green, eight-inch central heads followed by many sideshoots after you cut the main stem. 

Di Cicco is another Italian heirloom with smaller three- to four-inch heads that are held high above the foliage. This variety also yields many side shoots after you cut the central head. 

Purple Peacock Hybrid has large, deep-purple heads along with deeply cut, purple leaves with colorful pink veins. The leaves and heads change to dark green when cooked. 

Broccoli harks back thousands of years to the Romans and their great architecture, fantastic roads and building materials. For a tasty and healthy harvest right into early winter, plant fall broccoli, and Roman Pantheon or not, that is concrete advice for any gardener.

  • Paul Barbano writes about gardening from his home in Rehoboth Beach. Contact him by writing to P. O. Box 213, Lewes, DE 19958.