Vegetable
Cauliflower
Brassica oleracea var. botrytis · Brassicaceae
Also called: Heading Cauliflower
Cauliflower (Brassica oleracea var. botrytis) is a moderate-water vegetable well suited to Tucson and the low desert. It grows to 18-30 in tall and 18-24 in wide in full sun, with a moderate growth rate.
Cauliflower at a glance
- Water use
- Moderate (established)
- Sun
- Full sun (6+ hours) during the cool season.
- Mature size
- 18-30 in. tall and 18-24 in. wide
- Growth rate
- Moderate
- Bloom
- Yellow if allowed to bolt (edible curd is the immature flower head), Heads harvested in winter/early spring; bolts with heat
- Cold hardiness
- Cool-season; less frost-hardy than broccoli or cabbage — hard freezes below ~26 F can damage curds, and heat causes bolting. The most temperature-fussy of the brassicas.
- Soil
- Fertile, well-drained, organic-rich soil; pH 6.0-7.0. Heavily amend Tucson's alkaline native soil with compost.
- Native range
- Cultivated derivative of wild cabbage native to the Mediterranean / southern Europe
- Best used as
- Edible curd/head, Nutrient-dense cool-season vegetable, Fall/winter garden crop
- Wildlife
- Cabbage loopers, aphids, and harlequin bugs are common Tucson pests.
- Toxicity
- Edible and non-toxic to people. Generally safe for pets in small amounts; large raw quantities may cause GI upset in dogs.
How to grow Cauliflower in Tucson & the low desert
Watering
Requires steady, even moisture (about 1-1.5 in./week); any drought or heat stress causes ricey, loose, or bitter curds. In Tucson set out transplants Sept-Oct — it needs roughly two months of cool weather (around 60 F ideal) to form a quality head, so timing into the cool fall/winter window is critical.
Fertilizer & nutrients
Heavy feeder: compost plus balanced fertilizer at planting and nitrogen side-dressings every 3-4 weeks. Adequate boron and molybdenum prevent hollow stem and curd defects; consistent feeding is key to solid white curds.
Pruning & care
For white varieties, blanch by tying outer leaves over the developing curd to shield it from sun; harvest when the head is full but still tight and smooth.
Notes
The most demanding brassica for Tucson: it needs a precise, steady cool window, so plant transplants Sept-Oct so heads mature in the cool of winter before spring heat. Stress (heat, drought, transplant shock) easily ruins curds. Blanch white types; self-blanching and colored (orange/purple/green Romanesco) varieties simplify care.
Sources: University of Arizona Cooperative Extension – Pima County Monthly Gardening Guides; Tucson Organic Gardeners Planting Guide; Pima County Master Gardeners