Broccoli & Cauliflower in the Desert

Broccoli and cauliflower are often described as "tricky" in Phoenix, but that's mostly a timing problem. Get the planting date right and they're actually quite straightforward — and harvesting a perfect head of broccoli in January, when your friends in colder climates are buying it from a grocery store, feels excellent.

The key is understanding that these crops need to mature in cool weather, not just grow. They form heads (called "heads" for broccoli, "curds" for cauliflower) only when daytime temperatures are consistently in the 65–80°F range. Our October through February cool season gives them exactly that.

When to Plant

Set out transplants October 15–31. At 90–100 days from transplant, they'll be ready from mid-January into February. The UA Cooperative Extension Maricopa County calendar lists transplanting from mid-September as late as mid-January, so there's some wiggle room, but late October is the sweet spot.

Starting from seed: start indoors September 1–15, about 6–8 weeks before your transplant date. Seed-starting is easiest in a cool indoor space with grow lights, since it's still hot outside. Many gardeners just buy transplants from nurseries in October, which is easy and reliable.

Best Varieties for Phoenix

Broccoli

• Calabrese — Classic Italian broccoli, large central head followed by abundant side shoots. Excellent for Phoenix.
• Green Magic — Compact, early-maturing, very reliable. Great for smaller gardens.
• Di Cicco — Heritage Italian variety, smaller central head but prolific side shoots over many weeks. Very productive.
• Romanesco — Stunning spiral chartreuse heads, nutty flavor. Technically closer to cauliflower. Beautiful in the garden and the kitchen.

Cauliflower

• Snow Crown — Early-maturing, reliable, and one of the most heat-tolerant cauliflowers available. Good for Phoenix.
• Purple of Sicily — Purple-headed heirloom, slightly more heat-tolerant than white varieties. Turns green when cooked.
• Cheddar — Orange-pigmented, visually striking, slightly sweeter flavor than white cauliflower.

Spacing & Soil

These are large plants — give them 18–24 inches of space in each direction. They're heavy feeders, so amend soil generously with compost and add a balanced fertilizer before planting. Side-dress with additional fertilizer 4 weeks after transplanting.

Watch for cabbage loopers, small green caterpillars that chew holes in leaves during fall. Covering young transplants with fine insect netting keeps the moths off, and B.t. handles any loopers that get through without harming bees or ladybugs. Both are in the pest control picks on the Phoenix gear page.

Blanching Cauliflower

White cauliflower heads turn yellow and develop off-flavors if exposed to sunlight as they develop. When the curd first becomes visible (about the size of a golf ball), tie the outer leaves over it with a rubber band or twine to block sunlight. Check every few days — white cauliflower can go from golf ball to harvest-ready in less than a week on a mild winter day.

Colored varieties (purple, orange) don't need blanching.

Harvesting

Harvest broccoli when the central head is tight and dark green — before any yellow flower petals begin to show. Cut the central head, then leave the plant in the ground. It will produce smaller side shoots over the next several weeks, extending your harvest significantly.

Harvest cauliflower when the curd is firm and compact — don't let it get loose or "ricey." Once it starts to separate, quality declines quickly. When in doubt, harvest a day early.

Ready to go deeper?

Want every planting date in one place? My Phoenix Planting Calendar lays out what to plant, start indoors, or direct sow every month for Phoenix and the East Valley, including when to start brassica seeds and set out transplants. It's $7, instant PDF download.