In Utah, sow turnips twice: in spring around the April 12 to April 29 window for the last 32°F freeze, and again in late summer, timed so the roots size up before the first fall freeze, which arrives between October 18 and October 29. Those dates come from Salt Lake City, a mild valley. Most of the state is higher and colder, and southern Utah runs warmer.
The short answer for Utah
Turnips are a cool-season crop that handles light frost, so the spring date is a starting gate, not a hard wall. Sow in spring as soon as the soil is workable, and sow for fall by counting backward from the first-freeze window. Both windows come from NOAA’s 1991-2020 Climate Normals for the Salt Lake City station, and both are probabilities, not promises.
Here is what that means. The spring range, April 12 to April 29, is the 30 to 70 percent band of 32°F freeze probability. On the early date, the odds that spring’s last freeze is behind you are around three in ten. By the late date, they are around seven in ten. Even on April 29, a freeze can still show up in roughly three years out of ten. The fall range, October 18 to October 29, works the same way in reverse. Those are the dates when the chance that the first 32°F freeze has already happened climbs from 30 to 70 percent.
| Season | Frost window (Salt Lake City) | What it means for sowing |
|---|---|---|
| Spring | Last 32°F freeze, April 12 to April 29 | Sow once soil is workable; light frost is tolerable for turnips |
| Fall | First 32°F freeze, October 18 to October 29 | Count backward from these dates using the days to maturity on your seed packet |
The page does not have days-to-maturity figures for specific varieties, so the fall sowing date is yours to calculate. Take the number on the packet, add a couple of weeks of cushion because growth slows as days shorten and nights cool, and subtract the total from your local first-freeze date. That works only if your first-freeze date is right, which is where the rest of this page comes in. For the bigger picture of the crop, start with Growing Turnips and Rutabaga in Utah.
What will not work here
Copying Salt Lake City’s dates into a colder garden is the most common failure. The frost figures describe a mild valley floor. Someone gardening at higher elevation, where the facts say most of Utah sits, has a later spring and an earlier fall. A fall sowing timed for an October 18 freeze can be caught by a freeze weeks sooner, and the roots stop at marble size.
Slow crops lose first when the season shortens. Between the end of the spring window and the start of the fall window, Salt Lake City has about half a year of freeze-free weather. That is plenty for a quick turnip and a tight squeeze for rutabaga, which needs a long, cool stretch to finish. Sow rutabaga late, or in a short-season spot, and you get tops with little root underneath. Match slower crops to long seasons, and see The Best Turnips and Rutabaga for Utah before buying seed.
Spring turnips left to ride into summer heat turn woody, strong-flavored and quick to bolt. That is why the sowing calendar has two windows instead of one long one. Pull the spring crop while it is young, and let the late-summer sowing carry the harvest into fall, when cooling nights sweeten the roots.
Watering habits cause trouble too. Utah summers are dry, and a seedbed sown in late summer dries out fast. Turnip seed needs steady surface moisture to germinate, so a once-a-week soak will give you patchy, uneven stands. Plan on light, frequent watering until the seedlings are up, then back off. A thin layer of straw or shade cloth over the row helps hold moisture in the hottest weeks.
Overwintering is the last thing to rule out. The mean daily minimum of the coldest month at the Salt Lake City reference station is 24.2°F. That is an average, so many nights run colder. Roots left in unprotected ground through a Utah winter are a gamble, and the page has no evidence they survive reliably. Harvest before the hard freezes, or mulch heavily and accept the risk.
What changes across Utah
There is no single answer for Utah. The USDA Plant Hardiness Zone Map 2023, built on 1991-2020 normals, places the state across zones 4a to 9a. That is five full zones. The system measures one thing, the average annual extreme minimum temperature, so it describes winter cold, not the length of your growing season. The two usually move together, though, and a spread this wide tells you the state holds very different gardens.
If you garden in the north or at altitude, shift everything. Spring sowing moves later, because the soil thaws and warms more slowly. Fall sowing moves earlier, because the first freeze arrives ahead of Salt Lake City’s October 18 to October 29 window. A slow rutabaga that fits comfortably in the valley may not finish. A fast turnip is the safer pick, and a spring planting that matures before summer heat is often your best crop.
If you garden in southern Utah, the shift runs the other way. Spring opens earlier and fall closes later, so the fall window is long. The cost is heat: midsummer is harsh, and a seedbed sown too early for fall struggles to germinate. Wait for temperatures to ease before sowing the fall crop, and keep the soil moist.
Which zone applies to you is a question for the map, not this page. Look up your own location on the USDA Plant Hardiness Zone Map and see where it falls in the 4a to 9a spread. Then lean the calendar earlier or later accordingly, and treat anything beyond that as a starting estimate to test.
Where to check this for your own county
Utah State University’s USU Extension is the place to go next. Every county has an office, and its staff know the local frost patterns, soils and elevation quirks that a state-level page cannot capture. This page gives you the state view, built from one valley station. A county recommendation beats it, every time.
When you get there, look for two things. The first is a local planting calendar for your county or the nearest one at a similar elevation, with spring and fall vegetable dates. The second is any list of varieties trialled locally. A variety that performs in a county trial has already passed the test of your altitude, soil and summer heat, which no catalog description can promise.
A caution on what this page does not have: its facts include no Utah-specific turnip calendar from the extension service, so no county dates are listed here. If your county office publishes one, it replaces the dates above. If it does not, call or visit the office and ask what its staff would sow, and when, for your elevation. Local Master Gardener programs often keep this kind of knowledge, even when it is not in print.
Checking this against your own garden
Your own observations outrank every date on this page. Three are worth watching, and none needs an instrument.
- Soil warmth by feel. In spring, push your hand into the bed. If the soil is cold, wet and clumps into a sticky ball, wait. If it crumbles and no longer numbs your fingers, it is ready. A bed that reaches this point earlier than your neighbor’s is a warmer microclimate, probably sheltered or south-facing.
- First true leaves. After sowing, watch for the first true leaves, the ones that look like a real turnip leaf and not the rounded seed leaves. Fast arrival says your spot warms quickly. Slow arrival says it runs cool, and your fall sowing should go in earlier.
- First frost on tender plants. When frost blackens the leaves of basil, squash or tomatoes in your yard, you have your actual first-freeze date, which may be earlier than any table. Write it down every year, and after a few seasons you will have a calendar better than the state’s.
The notebook is the real tool here. Three or four seasons of dates turn the Salt Lake City numbers into your own.
Some gardeners also time this by the Moon: when to plant turnips by the moon, as almanac tradition rather than fact.
Common questions
Can I sow turnips before the last spring frost?
Yes, once the soil is workable. Turnips tolerate light frost, so you do not need to wait for the end of the April 12 to April 29 window. A hard freeze can still damage seedlings, so keep a row cover handy if one is forecast.
Can I sow turnips in summer for a fall harvest?
Yes, and in Utah the fall crop is often the better one. Count backward from your first-freeze date, using the days to maturity on the packet plus a cushion, and keep the seedbed moist while seeds germinate.
When should I sow rutabaga?
Rutabaga is slower than turnips, so it needs a longer, cooler stretch. Give it earlier sowing than turnips and avoid it in short-season, high-elevation gardens unless the variety is suited to them. Check the variety guidance linked above and your county extension office.
Do these dates apply to my county?
Only if your garden resembles Salt Lake City’s valley floor. The dates come from that one station, and most of Utah is higher and colder, while southern Utah is warmer. Use them as a starting point, and let your county extension office and your own frost notes override them.