Although a debate rages among horticulturists on whether the Romanesco cultivar of Brassica oleracea (Botrytis Group) is a broccoli or cauliflower, the flavorful and attractive member of the cabbage family is a perfect addition to your cool season garden harvest. Romanesco has a nutty flavor but its most attractive quality is the striking light green heads composed of numerous cone-shaped florets, each one growing in a logarithmic spiral creating a fractal pattern.
While gaining in popularity, Romanesco broccoli plants and seeds can be hard to find in mass-market garden centers. However, once you find plants or start seeds, the vegetable is as easy to grow as any broccoli or cauliflower variety.
|Common Name||Romanesco Broccoli, Romanesco Cauliflower|
|Botanical Name||Brassica oleracea (Botrytis Group) var. Veronica|
|Size||Height: 1 ft. 0 in. - 1 ft. 6 in., Width: 1 ft. 0 in. - 2 ft. 0 in.|
|Sun Exposure||Full sun|
|Soil pH||6.0 to 7.5, can tolerate slightly alkaline soil|
|Hardiness Zones||2a-11b USDA|
|Native Area||Rome, Italy|
How to Plant Romanesco Broccoli
Romanesco broccoli is a cool-season vegetable typically grown in the spring or fall because it does not tolerate heat. Because Romanesco plants are often difficult to find, it is best to start seeds indoors four to six weeks ahead of the anticipated last frost and then transplant them into the garden in early spring. For fall harvests, start seeds inside or seed in the garden in late summer.
The planting site should receive full sun and the soil loam-based and rich in nitrogen. Use compost for soil enrichment and mulch around the plants to help protect the surface roots and retain moisture. Place the plants or seeds 18 to 24 inches apart in well-drained soil. If using transplants, dig a small hole and fill in the soil around them so that the plant is at the same level it was in its pot. Water well and fertilize once or twice during the growing season. Romanesco is not a frost-tolerant plant and should be harvested before a hard freeze.
Romanesco Broccoli Plant Care
Once your plants have become established in the garden, they require the same care given to any variety of broccoli or cauliflower.
Romanesco plants require full sun to produce edible heads. The plants should receive six to eight hours of sun per day.
The plants or seeds should be established in fertile, loamy soil that drains well. The soil should be high in organic matter with a 6.0 to 7.5 pH; however, Romanesco can tolerate slightly alkaline soil. Do not plant Romanesco broccoli in the same location more than once every three or four years to help reduce disease.
The plants need plentiful, consistent moisture to produce edible heads. The soil should not be allowed to dry out completely before the next watering.
Temperature and Humidity
As a cool-season crop, Romanesco broccoli will not thrive in the high temperatures and excessive humidity of summer. Romanesco thrives in growing temperatures from 65 to 75 Fahrenheit.
Always start plants in fertile soil that is high in nitrogen. Apply one-half cup of high-nitrogen fertilizer (21-0-0 NPK) per 10 feet of row four weeks after transplanting or thinning to encourage vigorous plant growth. Place the fertilizer six inches away from the plants and irrigate it into the soil. Apply an additional one-fourth cup of nitrogen fertilizer when the Romanesco broccoli head is the size of a quarter.
Types of Romanesco Broccoli
- ‘Veronica’: The most widely available named cultivar reaches maturity in 77 days with good heat tolerance in the garden. Produces symmetrical, spiraled, lime green heads with tightly beaded, pointed domes. Holds its vibrant color even when cooked.
- 'Natalino': Produces bright lemon to yellow-green rosettes with a maturity date of 180 days. Can be eaten raw but loses color when cooked.
- 'Gitano': This Romanesco type produces deep green heads with an erect pyramidal curd full of spirals. Has good mildew resistance and tolerance to cold weather. Matures in 100 to 110 days.
Additional heirloom varieties can be found but tend to produce quite variable sizes of heads and unpredictable maturity. When searching for seeds, look in both the broccoli and cauliflower categories.
Harvesting Romanesco Broccoli
In most growing areas, Romanesco broccoli heads are ready to harvest 75 to 100 days after transplanting. Remove the entire head from the plant with a sharp knife. For varieties that produce several smaller heads, remove the individual stalks. Use immediately or store wrapped in plastic in the refrigerator for about a week.
Once the main head is cut, Romanesco broccoli does not produce new side shoots. The plant can be removed from the soil and composted.
How to Grow Romanesco Broccoli in Pots
Romanesco can be grown in pots following the same light, soil, temperature, and water guidelines as recommended for garden-grown plants. Each plant should be placed in a three-gallon pot to accommodate the large size of the plant. Water well and be sure to avoid planting during months with temperatures over 75 degrees Fahrenheit.
Pruning Romanesco broccoli is not recommended because it will greatly reduce vegetable production.
Propagating Romanesco Broccoli
While you can propagate Romanesco broccoli by placing a main stem in a glass of water to develop roots, the plant will not produce a new head. The best results for vegetable production come from transplants from a reliable garden center or starting your own transplants from seed.
You can save seeds to propagate your Romanesco broccoli. However, you may not get the same plant if the broccoli has cross-pollinated with another member of the Brassicaceae family. If you want to give it a try:
- Let the broccoli grow without harvesting until small yellow flowers appear and give way to seed pods.
- Once the seed pods turn brown and dry, the seeds should be mature. At that point, cut down the entire plant and hang it in a warm, dry spot with good air circulation for a couple of weeks so that the seeds continue drying.
- Once the seed pods have fully dried, gently cut them from the plant. Crumble them over a white cloth, so you can easily spot and separate the seeds from the chaff.
- Store the seeds in an envelope or airtight container labeled with the date. They should be viable for about five years.
How to Grow Romanesco Broccoli From Seed
- Sow Romanesco broccoli seeds indoors about six weeks before the last spring frost or before the first winter freeze.
- In pots or a seeding tray, add sterile, soilless seedling mix. Press the seeds one-fourth to one-half inch deep. Do not use bottom heat but keep the ambient heat around 65 to 75 degrees Fahrenheit.
- The seeds will germinate in about two weeks. Once the seedlings appear, place the tray in bright light to encourage growth.
- Fertilize with a half-strength liquid starter solution after the first true leaf appears. When two true leaves are present, fertilizer twice a week.
- When the plants have four or five true leaves, reduce watering and place the plants outside where they will receive wind protection and a couple of hours of sunlight to harden them off. Gradually expose them to more sunlight and keep them well watered.
- Plant in the garden after the chance of frost has passed in the spring or when the daytime temperature has dropped to around 65 degrees in the fall.
Potting and Repotting
If grown in a pot, Romanesco broccoli, should not require repotting because it does not overwinter. Plant in a large pot so the plant does not need to be disturbed during the growing season.
Romanesco broccoli is treated as an annual plant in the garden or in containers. Overwintering should not be attempted.
Common Pest and Plant Diseases
Romanesco broccoli is susceptible to the same pests and diseases as other members of the cabbage family. Watch for cabbage caterpillars (imported cabbageworm (Pieris rapae), diamondback moth (Plutella xylostella), cabbage root maggots, and cabbage looper (Trichoplusia ni).
Common diseases include blackleg, black rot, and clubroot. Disease control is best achieved by rotating where you plant crops each year and keeping the plants healthy.
What does Romanesco broccoli taste like?
Romanesco broccoli has a similar but milder, sweeter, and nuttier flavor than both broccoli and cauliflower. It can be eaten raw or cooked. To maintain its flavor and texture, don't overcook Romanesco.
Is Romanesco broccoli genetically modified?
No. Romanesco broccoli, grown and eaten for more than 500 years, is an edible flower bud of the species Brassica oleracea. It is related to both broccoli and cauliflower but is botanically different. Unlike its cruciferous cousins, the stalks form spirals of flower buds. These near-perfect fractals form the unique head of Romanesco.
How long does it take to grow Romanesco broccoli?
The 'Veronica' variety of Romanesco broccoli takes about 75 days to reach maturity once the seedling is transplanted into the garden. It takes about six weeks from seed germination until the seedling is ready to transplant into the garden.
Broccoli. University of Saskatchwan College of Agriculture and Bioresources.
Broccoli in the Garden. Utah State University
What is Romanesco Broccoli? The Spruce Eats.com