When to plant broccoli in Utah
Utah’s average last spring frost is May 5, and the first fall frost typically arrives around October 5 — about 153 frost-free days (USDA zones 4a, 5a, 5b, 6b, 7b, 8a, 9a). Broccoli needs 60–85 days to mature, which fits comfortably within Utah's growing season.
Utah covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant broccoli in Utah: the short answer
For a spring planting, plant out Apr 14 – May 1, with seeds started indoors Mar 17 – Mar 31. Seeds germinate in soil from 45 to 85°F.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow broccoli in Utah, step by step
- Start seeds indoors (Mar 17 – Mar 31). Sow seeds ½ inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 75°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 6.0 and 7.0. Dig in compost before planting.
- Plant out (Apr 14 – May 1). Space plants about 18 inches apart in rows 30 inches apart. It tolerates a light frost but not a hard freeze. As a cool-season crop it does best before summer heat arrives in Utah.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: cabbage worm, cabbage looper, aphids, flea beetle, cabbage root maggot. Diseases and disorders: clubroot, black rot, downy mildew.
- Harvest (from about Jun 20 – Jul 15). Broccoli takes 60-85 days to reach harvest. Days to maturity counted from transplant. Keep cutting side shoots after the main head for weeks. Spring crop must size up before heat or it buttons.
Figures come from our crop data; dates use Utah’s average frost dates. More in the full broccoli growing guide.
What Utah extension says about broccoli
- Broccoli can be grown from seed or transplants. Broccoli grown for transplants should be sown 6-7 weeks before the expected planting date. (Utah State University Extension, Broccoli in the Garden (2020))
- Transplants may be planted 2-3 weeks before the last frost-free date for the growing area. Seeds may go in at the same time, 1/4 to 1/2 inch deep. (Utah State University Extension, Broccoli in the Garden (2020))
- Broccoli grows best and gives its highest yields when temperatures do not exceed 75°F, and it is not seriously damaged by temperatures down to 28°F. (Utah State University Extension, Broccoli in the Garden (2020))
- Thin seedlings or transplant broccoli 12-18 inches apart in the row, with rows 2-3 feet apart. (Utah State University Extension, Broccoli in the Garden (2020))
- Water deeply and infrequently while keeping the soil evenly moist. About 1-2 inches of water are needed per week. (Utah State University Extension, Broccoli in the Garden (2020))
- Apply 1/2 cup per 10 feet of row of a nitrogen fertilizer (21-0-0) 4 weeks after transplanting or thinning, and another 1/4 cup when the head is the size of a quarter. More nitrogen after the main head is cut encourages side shoots. (Utah State University Extension, Broccoli in the Garden (2020))
- Buttoning, the growth of small premature heads, happens when plants have been exposed to cold weather or stressed for water or nutrients. Larger transplants are more prone to it, so choose plants with 4-6 leaves. (Utah State University Extension, Broccoli in the Garden (2020))
- Hot caps and fabric covers protect seedlings and transplants from frost, and fabric covers also protect young plants from insect pests such as cabbage worms and loopers. (Utah State University Extension, Broccoli in the Garden (2020))
- Mature heads are 6-12 inches across and are cut with a 6 inch stem, before the flower buds open. With extra water and fertilizer, broccoli goes on to make many 3-6 inch side shoots. (Utah State University Extension, Broccoli in the Garden (2020))
- For fall broccoli, choose early maturing varieties and plant 50-75 days before the date you expect them to mature. Its listed varieties mature in 50 days (Packman), 55 days (Green Comet) and 65 days (Premium Crop). (Utah State University Extension, Broccoli in the Garden (2020))
Broccoli planting dates by USDA zone in Utah
Utah spans USDA zones 4a, 5a, 5b, 6b, 7b, 8a, 9a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the broccoli dates shift with them.
| Zone | Last frost | First frost | Season | Start indoors | Plant broccoli |
|---|---|---|---|---|---|
| Zone 4 | May 10 | Sep 25 | 135 days | Mar 22 – Apr 5 | Apr 19 – May 6 |
| Zone 5 | Apr 30 | Oct 5 | 160 days | Mar 12 – Mar 26 | Apr 9 – Apr 26 |
| Zone 6 | Apr 15 | Oct 15 | 185 days | Feb 25 – Mar 11 | Mar 25 – Apr 11 |
| Zone 7 | Apr 5 | Oct 25 | 200 days | Feb 15 – Mar 1 | Mar 15 – Apr 1 |
| Zone 8 | Mar 20 | Nov 5 | 230 days | Jan 30 – Feb 13 | Feb 27 – Mar 16 |
| Zone 9 | Feb 20 | Nov 30 | 280 days | Jan 2 – Jan 16 | Jan 30 – Feb 16 |
When to plant broccoli in nearby states
Questions gardeners in Utah ask
When is the best time to plant broccoli in Utah?
Plant broccoli transplants outdoors in Utah between April 14 and May 1. That timing is set by Utah's average last spring frost of May 5; Utah spans several climates, so cooler and higher parts of the state run later.
When should I start broccoli seeds indoors in Utah?
Start seeds indoors between March 17 and March 31, about 6 weeks before the last frost, so the seedlings are ready to plant out from April 14.
Can I plant broccoli in the fall in Utah?
Yes. For a fall crop, start transplants between June 26 and July 13, so the crop matures in cool weather before Utah's first frost around October 5.
When will broccoli planted in Utah be ready to harvest?
Planted on time, broccoli is usually ready from about June 20 to July 15, 60-85 days after transplanting.
When is the last frost in Utah?
On average around May 5, with the first fall frost around October 5 - about 153 frost-free days. Your town may differ by two weeks or more.