Master Gardeners of Napa County had a cauliflower seedling give-away last September. I picked up three different varietals – “Amazing” (looks like a standard white variety you see in the grocery store), “Veronica” (a cone-shaped, chartreuse beauty), and Graffiti (purple, and loaded with beneficial anthocyanin antioxidants). I have never managed to successfully grow cauliflower in my veggie beds. I was curious to see if I might have better success this time around in an area that I had recently converted from a Bermuda grass and Malva parviflora “lawn” into a new, compost-enriched edible landscape that includes (self-seeding) Mache lettuce (Valeriana locusta), calendulas, Swiss chard, culinary sage, lavender, licorice plant, and Egyptian onions sprinkled throughout.
Following the advice of the expert, masked and gloved distribution team, I kept the four-inch pots in a cool, shaded location, since a two-week heat wave was forecast and planted the five-inch seedlings in early October. The warm fall and hand-watering got the seedlings well established in time for the first sparse rains and cooler temperatures. By late February the “Amazing” was about 11 inches across and the other two varietals about 8 inches.
Following are instructions for growing cauliflower successfully. Plant starts now to get them growing before summer heat sets in.
Sun Requirements — Cauliflower is a cool-season crop, but it needs full sun, at least 6 hours a day. Site your plants in a south-facing area where they will receive winter sun. Plants will not tolerate blazing heat. Be prepared to protect your plants from a hot spell in late summer or early fall by shading them and watering more.
Watering — Water deeply using drip or furrow irrigation, and avoid wetting the leaves. To produce hard, solid, flavorful heads, the plants must not experience water stress. If the plants do not receive consistent rainfall or irrigation, they will have poor texture and may develop strong “off” flavors. Dig down to see how far water is penetrating; water to 8 inches twice a week, less when rains start.
Planting — Cauliflower plants can get very large, so space them at least 18 inches apart, more if possible. When transplanting cauliflower bury them to the first leaf. To avoid a build-up of soil diseases, don't plant cole crops in the same spot each year. See crop rotation, Napa MGs Healthy Garden Tips → Vegetables→ Crop Rotation http://napamg.ucanr.edu/Gardening_Books/Healthy_Garden_Tips_A/
Chewed leaves are often caused by imported cabbageworm http://ipm.ucanr.edu/PMG/r108301111.html . Treat chewed leaves by picking off the green caterpillars or spray with Bt, Bacillus thurengiensis. It is a safe, naturally derived pesticide. It will also kill butterfly larva (caterpillars), so use prudently.
Harvest cauliflower when it forms a nice head or “curd” 5 to 6 inches in diameter, 75-85 days. It can be as little as 55 days or as many as 100. If you leave it in the garden too long, it will start to flower, becoming bitter and inedible. Blanching (tying the leaves up) is not necessary for colored cauliflower. The white “Amazing” cauliflower is self-blanching.
Master Gardeners are following recommended social distancing guidelines that keep everyone safe, Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143. Volunteers will get back to you after they research answers to your questions.
Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.
Photo credits: Rainer Hoenicke
References: UCANR Publication 7219
sonomamg.ucanr/Food_Gardening/Feature_Vegetables/Cauliflower/