Sonoma County Master Gardeners Helping Sonoma Gardeners

Ladies and Gentlemen, start your broccoli!

Broccoli, a member of the Brassica (Mustard) family, has been under cultivation for centuries.  The Etruscans brought the vegetable to Italy, where it became a favorite with the Romans.  They knew two varieties, the Calabrese (the most familiar form today) and a purple sprouting type. Visualize the mature broccoli plant; the Romans called it the “five fingers of Jupiter”.  Apicius included recipes for broccoli in his cookbooks, recommending a touch of cumin and coriander seeds with olive oil and wine.

Catherine de Medici brought broccoli, along with other vegetables and the chefs to cook them, when she arrived in France in 1533.  The vegetable took a while to cross the Channel, for in the early 1700s it was thought of as “Italian asparagus”.  Thomas Jefferson, the avid and curious gardener, was planting broccoli in Virginia by 1767.  

But broccoli didn’t really catch on in the United States until the D’Arrigo brothers, Italian immigrants, cautiously planted out some test fields near San Jose in 1922.  They shipped some crates to Boston, and the rest, as they say, is history.  Today, the United States leads the world in broccoli production and California grows 92% of the U.S. crop.

So that must mean that we home gardeners here in Sonoma County should be able to grow this vegetable easy-peasy, right?  Well, sort of.  Broccoli is a cool weather crop that does poorly in summer heat.  It can bolt and the heads can split.  But with careful selection of varieties and appropriate (seasonal) planting schedules, you should do well.  At this time of year in Sonoma County we are planting long-season broccoli.  There are two distinct types of broccoli: short-season and long-season.  ‘Short’ and ‘long’ refer to the days between transplanting and harvest.  Short-season varieties take 60-90 days and can be started from seed between March and July.  The long-season varieties take 90-120 days, coming to maturity between December and March.  These are tall plants, often up to 3’ when the first heads appear.  (The short-season varieties, such as Calabrise and De Cicco, are tolerant of summer heat and much shorter – about 1 ½’ tall when the first heads appear.)

 Another important consideration is crop rotation.  Do not plant brassicas of any kind in the same space more than once every four years, as you run the risk of disease and insect pest build up.  Remember that favorites like arugula, radishes, and flowering kale are all part of the Mustard family.

Two long-season varieties that are recommended for fall planting are Romanesco and Shogun F1.  There is also a Romanesco hybrid called ‘Minaret’, with small heads, only about 5 ½”.  Romanesco is an absolute stunner of a broccoli.  The literature describes it as a fractal, but I think of it as a lime green Christmas tree.  It is sculptural and varies in size.  You might be tempted to use it as a centerpiece, but it is more than eye candy.  This variety does not develop any side shoots, but grows a single, dense head, quite like a cauliflower.  The Shogun F1 is also a long season variety, but it is a ‘sprouter’, which means that it will form a central head, followed by smaller side shoots/sprouts which are harvestable.  In addition to seeding these long-season varieties, if you can find established starts of short season varieties (like Calabrise or De Cicco) you could set them out in early August for a 60-90 day harvest.  Check seed packets carefully for days to harvest!

So now that we have sorted out long season/short season, sprouting/non-sprouting issues, are we ready to plant?  Not so fast.  Remember the earlier admonition about crop rotation and check your location.  Broccoli prefers soil with a pH of 6 to 6.8, slightly acidic, which should be okay in most of Sonoma County. You also want to provide ample regular water and a good feeding of nitrogen, calcium and potassium.  Broccoli does not tolerate stress; inadequate water, too much heat, cold, or poor soil over a period of time will result in stunted plants with small heads. And there are chewing and sucking evils that can beset your broccoli.  Broccoli is particularly vulnerable to caterpillars and cabbageworm, both of which can be treated with Bacillus thuringiensis (Bt).  Aphids can also be problematical if they infest the developing heads.  Try insecticidal soap or blast them off with a strong jet of the garden hose.  Some chewers like the harlequin bug can be handpicked and squished.  

From early August through September you can start setting out transplants or seeding for a late fall/early winter harvest of your favorite long-season broccoli.  If seeding, plant seed ¼” to ½” deep and ½” apart in seed trays.  Give the seeds ample light and warmth.  Transplant either purchased plants or your young, vigorous seedlings when about six weeks old; plants left too long in the seed trays produce “button” heads soon after planting and then refuse to grow further. Space them about 15” apart as they like to bush out (remember those “five green fingers”).  Remember, long season broccoli will mature 90-120 days after transplantation.

While your plants are growing, side-dress with nitrogen fertilizer or seaweed extract, which is rich in nitrogen.  Organic mulch will suppress weed growth and add nutrients, or you can use shallow cultivation to get rid of the weeds.  The final step in growing is, of course, the harvesting.  The ideal time to pick the heads is when they are dense, dark green (lime green if Romanesco) and 4”-6” in diameter.  If you planted a sprouter, harvesting the central head stimulates the side shoots to develop for future pickings. If you let the head go to flower, it will be past its prime and the plant will cease production.  

For those of you who want to try something different, an interesting variety of broccoli is called leaf broccoli, or Spigariello.  It is just like broccoli but with narrower leaves, and grows three to four feet high. The foliage is distinctive, with medium blue-green color which could be attractive in an ornamental edible garden.  This plant seems to be a broccoli for all seasons.  The seeds can be started either in March/April or July/September for either a summer or fall harvest.  Though still technically a cool weather crop, Spigariello appears to tolerate warmer growing conditions than do most broccolis. Leaf broccolis are dependable germinators; once several true leaves have appeared, transplant the seedlings about eight to twelve inches apart.  The leaves are ready to harvest at any stage of the plant’s growth.  You could harvest dozens of leaves at any one time, just don’t totally defoliate the plant.  It will continue to grow and replace those harvested leaves.

Broccoli is high in vitamin C, vitamin A and Folacin and contains multiple nutrients which are thought to have potent anti-cancer properties.  For the table, it is usually boiled or steamed, but can also be eaten raw, stir-fried, microwaved, baked in casseroles, added to soups or roasted with garlic and oil.  For those who are hesitant to try it (or if you wish to feed it to avowed broccoli haters), pureeing steamed broccoli with sautéed garlic and either butter or olive oil produces a delicious dish that resembles green mashed potatoes, is unrecognizable visually as broccoli, and may well make some converts!
Broccoli has come a long way in the American gastronomic pantheon, hardly recognizable as the butt of the infamous 1928 New Yorker cartoon, in which a mother offers a serving of broccoli to her small child who responds, “I say it’s spinach and I say the hell with it.”  We say “It’s broccoli!  Bring it on!”

©Sonoma County Master Gardeners