Romanesco: the trippiest plant in the garden. This eye-pleaser, sometimes classified as either a cauliflower or broccoli, is a unique and beautiful member of the Brassica oleracea species. Originating near the Mediterranean coast of Italy sometime in the 16th century, this edible flower bud grows into a spiral of spirals of spirals, a striking example of fractal geometry found in nature. Plants can grow to 3′ tall before producing flower buds. Leaves are large, dark green, and resemble those of cauliflower. If left to go to seed or grown in too-warm conditions, it will bolt and produce small yellow flowers. The taste is described as nuttier and earthier than cauliflower, with a more delicate flavor and crunchier texture.
The Veronica F1 hybrid variety is one of the more popular choices for gardeners. In cool weather, the heads will develop a pale lime green color, while those maturing in warmer conditions will show some white to light pink coloration. It will do best when planted in the summer for a fall harvest, or winter harvest in mild climates. It also offers some disease resistance to the diseases Fusarium Yellows and Fusarium Wilt.
Seed Depth: 1/2″
Space Between Plants: 18–24″
Space Between Rows: 24–36″
Germination Soil Temperature: 60–85°F
Days for Germination: 5–21
Sow Indoors: 6 weeks before average last frost date. If seedlings get leggy before transplanting, just plant them deeper and they will send out new roots from the stem.
Sow Outdoors: 2–3 weeks before average last frost date. For a fall crop, sow 9 weeks before average first frost date.
Vegetative: Can be propagated by taking cuttings of side shoots from the main stem, but this is not common practice.
Grows best in cool weather, and buds will not develop well in extreme heat or drought. Tolerant of frosts down to 20–25°F, seedlings are hardy, but the mature flower heads will be damaged in a hard freeze. Seedlings should be transplanted outside once the soil temperature is at least 60°F. In mild climates like USDA Zone 8 and up, grow as a winter vegetable.
Natural: Full sun. Tolerates partial shade.
Artificial: Will grow well under a variety of artificial lamps including LED or fluorescent. Provide at least 7–8 hours of light daily.
Soil: Prefers loose, well-drained loamy soils with a high amount of organic matter to support its fast growth. A pH of between 6.0 and 7.5 will keep plants healthy and nourished.
Soilless: Grows well in a perlite, gravel, or volcanic ash media. Germinate seedlings in a soilless mix.
Hydroponics: Will thrive in larger media-based hydroponic systems.
Aeroponics: Thrives in aeroponic systems.
Water: Requires moderate levels of water. Consistent soil moisture is best, but since it grows in cool weather, you won’t have to worry about frequent watering unless there is a particularly dry or hot spell. Drying out can cause plants to bolt, so be sure to monitor soil moisture regularly.
Nutrients: Requires moderate to high levels of nutrients. Add compost or an organic fertilizer that is higher in potassium and phosphorus than nitrogen to your soil before planting. Boron and calcium levels in particular may need to be added.
Foliar: Will benefit from foliar feedings of compost tea or liquid seaweed if grown in poor soils. Apply to leaves 2 weeks after transplanting or about 6 weeks after starting seeds outside.
Mulching: Use mulch to keep weeds under control, moderate soil temperature, conserve moisture, and protect plants during cold winters.
Deficiency(s): Soils deficient in lime (with low or acidic soil pH) will cause plants to be stunted and possibly develop clubroot disease. A boron deficiency may also cause problems such as browning and curling of leaves and a failure of head development.
Rotation: A 3-year rotation away from all plants in the brassica family will protect plants for pest and disease issues. Plant romanesco following legume crops like beans and peas to allow it to take advantage of the rich soils that these nitrogen-fixing friends create.
Companions: Grows well with celery, nasturtiums, and other aromatic herbs that will help to repel pests. Avoid beets, tomatoes, onions, and strawberries.
Harvest: Cut mature heads from the plant, leaving 1–2″ of stem attached to the base. Look for heads with tight spiraling buds at approximately 3–4 months after planting. Ideally, pick before they start to spread and form flowers. If you wait until it’s too late, do not worry! They are still edible. Besides, removing the maturing heads will promote the formation of secondary heads and side shoots which can be harvested as frequently as every few days. When the first heavy frost threatens, remove all the remaining heads at any stage of development. If you want to eat some of the leaves as a cooked green, you can cut a few lower ones off. Just don’t take too many, or you risk stunting the growth of the head.
Storage: Quickly cooling romanesco heads after harvest will extend their storage life. Keep them in a plastic bag in the refrigerator for up to a week. The earlier you eat it, though, the better.
Fun Fact: True mathematicians will tell you that romanesco can’t possibly be a true fractal, since that would require that it be infinite. Instead, call it an approximate fractal.
Preserve: Romanesco can be blanched and frozen for later use. You can also pickle or lacto-ferment small chunks of this wildly shaped vegetable for a crazy looking preserved food.
Prepare: The delicate flavor of romanesco is best when eaten raw or lightly cooked. You can sauté, roast, steam, or boil it. The stem is also edible and can be used along with the buds. Leaves can be served as a cooked dish. You can even mash it like potatoes or grind and use it as a wheat substitute in pizza crusts or tabbouleh. Now that’s groovy!
Nutritional: Provides vitamin(s) C, K, and A. Also a good source of dietary fiber, carotenoids, iron, calcium, zinc, and folate. A 100g serving contains only 25 calories, so eat up!
Medicinal: Like many members of the brassica family, romanesco is reputed to have powerful anti-cancer properties. It is also high in anti-oxidants and phytochemicals and may be helpful to maintain a healthy liver. The zinc content may help to offset losses of the sense of taste.
This Romanesco Curry looks so beautiful we’re not sure we could bring ourselves to eat it!