Vegetable
Broccoli
Brassica oleracea var. italica · Brassicaceae
Also called: Calabrese, Sprouting Broccoli
Broccoli (Brassica oleracea var. italica) 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.
Broccoli 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 (the edible 'head' is unopened flower buds; let it flower only to save seed), Heads harvested late fall through winter/early spring; bolts to yellow bloom with heat
- Cold hardiness
- Cool-season; frost-tolerant and even sweetened by light frost, hardy to roughly 25-28 F. Mature plants tolerate Tucson winter cold; sustained spring heat causes bolting.
- Soil
- Fertile, well-drained soil rich in organic matter; pH 6.0-7.0. Amend Tucson's alkaline soil generously with compost.
- Native range
- Cultivated derivative of wild cabbage native to coastal Mediterranean / southern and western Europe
- Best used as
- Edible flower heads and side shoots, Nutrient-dense cool-season vegetable, Fall/winter garden crop
- Wildlife
- Cabbage loopers, aphids, and harlequin bugs are common Tucson pests; flowers attract pollinators if allowed to bloom.
- Toxicity
- Edible and non-toxic to people. Generally safe for pets, though large amounts of raw brassica can cause gas/GI upset in dogs.
How to grow Broccoli in Tucson & the low desert
Watering
Water deeply and consistently, about 1-1.5 in. per week (more in dry/windy spells); even moisture prevents premature buttoning and bitter heads. In Tucson, set out transplants Sept-Oct (or sow seed late summer); it needs the cool fall/winter window to head up before spring heat.
Fertilizer & nutrients
Heavy feeder: incorporate compost plus a balanced fertilizer at planting and side-dress with nitrogen at 3-4 weeks and again as heads form. Boron and adequate nitrogen are important for good head development.
Pruning & care
Cut the central head while buds are tight and before yellow flowers open; leave the plant to produce smaller edible side shoots for weeks afterward.
Notes
Best planted as transplants in Sept-Oct for a fall-to-winter Tucson harvest; a second short window exists in late winter but spring heat limits it. Watch for buttoning (tiny premature heads) caused by transplant stress or heat. Cabbage-family pests are the main challenge — scout undersides of leaves.
Sources: University of Arizona Cooperative Extension – Pima County Monthly Gardening Guides; Tucson Organic Gardeners Planting Guide; Pima County Master Gardeners