Going back to our high school biology lesson, wherein everything under the sun is classified according to kingdom, phylum, class, order, family, genus, and species, we find that broccoli and calabrese both belong to the same family, Brassicaceae, as well as the same species, Brassica Oleracea.
The difference is in the cultivar groups that each belongs to. Broccoli belongs to the group Cymosa, and has purple flowering heads. Calabrese belongs to the group Italica, and has green flowering heads. That’s right, that green “broccoli” you’ve been eating ever since you can remember is actually calabrese!
True broccoli (Cymosa, the purple stuff) is virtually unknown in the U.S., but not unavailable. Everwilde Farms grows it organically and sells the seeds through Amazon.Com here:
Calabrese (Italica, the green stuff we all call broccoli) comes in many varieties; among them are Bonanza, Corvet, De Cicco, Emperor, Express Corona, Green Comet, Green Sprouting, Green Valiant, Italian Sprouting, Oktal, Premium Crop, Romanesco Minaret, Super Dome, and Waltham 29.
De Cicco is a popular variety, due to its productivity and disease resistance, that you can order from Nature Hills Nursery by clicking on their banner above or through Amazon.Com here:
Best Climate to Grow: Both broccoli and calabrese require shelter from strong winds. Calabrese is frost tender, while broccoli is more frost hardy. Both will bolt in hot weather, so the earlier the summer harvest or the later the fall harvest the better.
Light Requirements: Lots of sun. Neither will thrive in the shade.
Soil Requirements: Both broccoli and calabrese require nitrogen-rich soil that has been well-manured the previous season. They require a neutral to slightly acidic pH level. Amend as needed to ensure the proper pH level before planting.
Feeding and Water Requirements: The soil must be kept moist at all times; drip irrigation combined with mulching is recommended. For optimum growth, fertilize with hydrolyzed fish or an organic 10-10-10 fertilizer when you plant and again when the heads begin to form.
When to Plant: In the spring, if starting the seeds indoors, begin 6-8 weeks prior to the last frost date, and harden off and transplant into the ground about 3 weeks prior to the last frost date. If sowing directly in the ground, do it a week or two prior to the last frost date for your area.
If you are planting for a fall harvest, sow the seeds directly in the ground 3-4 months prior to the first frost date.
Planting Depth and Spacing: If you are sowing directly in the ground, for broccoli plant 2 or 3 seeds together ½ inch deep and 24 inches apart. If planting in rows, make sure the rows are 24 inches apart as well. After germination, remove the weaker of the seedlings. For calabrese plant 2 or 3 seeds together ½ inch deep and 12 inches apart. If planting in rows, make sure the rows are 12 inches apart. After germination, remove the weaker of the seedlings.
If you will be transplanting seedlings from indoors, space the broccoli seedlings and calabrese seedlings as directed above. The purple broccoli plants are quite a bit larger than the green calabrese, as evidenced by the plant spacing recommendations.
Container Requirements: Not recommended. They simply take up too much room.
Harvesting and Storage: Harvest the main head with a sharp knife when it is large and firm. The sideshoots will continue to grow, providing you with smaller heads or buds to harvest as the season continues. If the plants bolt, you can either cease irrigation and harvest the dry seed stalks for seed, or you can continue irrigating and harvest the flowering seed stalks to eat – they are absolutely delicious in salads, stir-fries, and pasta primavera.
Harvesting Seeds: When the broccoli or calabrese has bolted, stop irrigating and allow the plants to dry, very carefully harvesting the seed stalks to prevent the pods from breaking and scattering the seeds. Use a fine mesh strainer to separate the seeds from the pod chaff. The seeds will keep up to 5 years if stored properly in a cool, dry place.
Pests to Monitor: Cabbage Loopers, White Butterflies, and Worms; Caterpillars, Cutworms, and Flea Beetles. Visit our pest control beneficials, barriers, scare tactics, homemade organic pesticide, and commercial organic pesticide pages to see your options and choose your weapons.