Utah · zones 6a–8b
When to plant broccoli in Utah.
Sow or transplant between Mar 10 to Apr 7 in a typical year, keyed to Utah's median last frost around May 1. A second, fall sowing fits Jun 21 to Jul 31. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Broccoli dates for a typical Utah season.
1 · Start indoors
Jan 27 to Feb 24
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Mar 10 to Apr 7
Keyed to the ~May 1 last frost. Sow 0.5" deep, 18" apart.
Fall round
Jun 21 to Jul 31
Counted back from the ~Oct 5 first frost.
Harvest
~60 days later
~1.2 lb per plant over ~3 weeks.
Utah spans more than one climate: Zone 6 is the most common zone, but the state runs 6a to 8b. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
Utah growing notes
Utah's thin mountain air changes what a broccoli head looks like.
Utah's valley heat turns curd loose before it should
Utah's valley summers hit broccoli at the worst possible moment. A stretch of days above 95 degrees while the growing tip is switching over to bud formation, roughly ten days before any crown shows in the center of the plant, produces uneven beads and a head that loosens into yellow-green rice instead of holding tight, well ahead of the 60 days the plant needs from transplant to mature properly.
A light shade cloth, thrown over the row once heads begin to form and left on through the final 2 weeks before harvest, works by dropping leaf temperature during that window rather than by blocking light. Checking head tightness by hand every few days, rather than relying on how big the head looks from above, catches the moment a head starts to loosen; once ricing starts there is no reversing it, so cut a touch early rather than let a nearly-tight head finish loose.
A short season means picking one window and committing
Utah's growing season runs close to 157 days between frosts, and broccoli's 60-day run from transplant eats a sizable share of that in a single planting, which leaves less room than a longer-season state has for a spring crop to fail and still recover with a fall replant. Starting transplants indoors well ahead of the last frost, rather than direct-seeding or buying late transplants, is what makes a spring Utah broccoli crop reliable rather than a race against the calendar.
The fall planting benefits from Utah's cooling autumn air in a different way: heads finishing as nights ease down hold their tight, dense shape longer before ricing becomes a risk, since the 95-degree stretch that pushes a summer head to loosen fast is simply off the table once daytime highs drop back through September and October. Many Utah gardeners treat the fall crop as the more forgiving of the two windows for exactly that reason.
Aphids hide inside the one part you cannot rinse clean
Cabbage worms and loopers, the pale green caterpillars that leave ragged holes in outer leaves, are the easier problem to spot; a weekly check of 10 plants, counting caterpillars on the underside of leaves, tells a grower whether the population has crossed the point where a Bt spray is worth applying. Bt kills only caterpillars, leaving pollinators working nearby flowers alone, which matters in a Utah garden that likely also has squash or beans depending on the same bees.
Aphids are the tougher problem because they cluster down inside the forming head itself, out of sight until the head is already cut. A hard spray from a garden hose, aimed up and under the head from below 2 to 3 days before the planned harvest, dislodges most of a colony without bruising the curd, and works better here than any spray applied to a head that is about to be eaten fresh or lightly steamed.
In Utah: watch for
The pests that find broccoli here.
A middle-length season, about 157 frost-free days, means broccoli overlaps cabbage worms & loopers for a stretch each summer. Check plants every week or two and treat early.
Green caterpillars chewing ragged holes; green droppings.
Organic fix: Handpick, cover with netting, spray Bt.
Gray-green clusters tucked into the leaf folds.
Organic fix: Blast with water, then insecticidal soap.
Tiny holes peppering the young leaves.
Organic fix: Row cover from day one; diatomaceous earth.
Black rot
Yellow V-shaped wedges cutting in from the leaf edge, veins blackening inside.
Organic fix: Pull infected plants, water at the base, keep brassicas out of that bed 3 years.
Seedlings wilt, yellow and stall for no reason; white maggots tunnel the roots.
Organic fix: Row cover before the flies are up, when yellow rocket blooms; rotate the bed.
Your season math: Utah gives broccoli about 157 frost-free days, and it needs roughly 60 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting broccoli in Utah: questions
When should I plant broccoli in Utah?+
In a typical Utah year, sow broccoli or set out transplants between Mar 10 to Apr 7, keyed to the state's median last frost around May 1. There's also a fall window: Jun 21 to Jul 31. Your exact dates shift with your ZIP code and microclimate.
When do I start broccoli seeds indoors in Utah?+
Start seeds inside about 6 weeks before set-out: roughly Jan 27 to Feb 24 for a typical Utah season.
What USDA zone is Utah?+
Utah spans zones 6a–8b, mostly zone 6. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many broccoli plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.