Transplant outside at an opportune time. Planting Romanesco broccoli seed in late summer will yield a fall harvest.
As previously stated these plants need plenty of space, leave at least 2 feet between rows with plants being 3 feet apart within the rows.
They will grow under less than optimal watering, but the heads will not develop as large or as tasty . It is best to keep these plants well watered and consistently wet - not water logged - just moist. Provide at least an inch of water weekly, soaking the soil to about a 6 inch depth. Romanesco Brossoli needs consistent moisture to produce desirable large, tender heads. Dry spells can cause the heads to split and destroy the 'algorithmic" heads appearance and quality.
Romanesco is a heavy feeder, and plants take up nutrients best when the soil pH is between 6.0 and 7.5. A nitrogen rich fertilizer is also advisable.
About three weeks after transplanting, side-dress with blood meal or fish emulsion, and water deeply. Repeat this monthly until about one week prior to harvest.
A prolonged period of cold nights or very warm days will produce tiny, immature heads known as buttons. Protecting Romanesco brocolli plants with Cloches or row covers is at times a good idea.
An occasional problem encountered when growing Romanesco Broccoli is bolting to Seed - particualrly under hot conditions. In temperate zones you can get 2 crops, one in spring and another in early fall. Excessive warm spells can also cause the heads to prematurely open.
Broccoli Romanesco is a cool season plant that rapidly bolts to seed when exposed to high heat. In temperate zones you can get a spring crop and an early fall crop. In regions with Hot summers you would be well advised to start earlier in the spring to harvest before the sun bares down full force, or later in the growing season for a fall harvest.
Harvest before the plant flowers. Cut directly below the point where the stems start to separate. Once you've harvested the main head, side shoots will sometimes grow. So long as the weather permits you can keep harvesting the side shoots.
Romanesco Broccoli is tasty enough to devour fresh or steamed but can also be frozen. It can be refrigerated for up to 2 weeks.