Planting calendars

Utah valleys and high plateaus calendar

USU Extension last-frost dates from St. George and Salt Lake to Logan, Park City, and Woodruff, with two planting tracks.

By the Thin Air Harvest editorial team. Updated November 1, 2026.

Utah does not have a statewide planting day. Utah State University Extension’s suggested planting-date table says the average last spring frost varies by city, and it prints a city-by-city list used to time four groups of vegetables.

A 2019 USU note adds the reason gardeners get caught: frost-free days in Cache Valley alone run from about 113 days in some valley towns to about 158 days on the USU campus, and cold air pooling makes a lower spot colder than a bench. Use the city that matches your elevation and landform. If two published numbers disagree, both are shown here. They are not averaged.

The figures below are average last spring frost dates as printed by USU Extension, except Park City and the frost-free day counts, which come from the 2019 note and are marked.

Provo’s airport and Provo’s campus differ by about three weeks in the same table. Logan’s campus and Logan’s Southwest Farm differ by about two weeks. That is the whole lesson. “Utah County” is not a planting date.

A bench is not a river bottom. Park City’s June 9 and 92-day season in the 2019 note belong with the mountain-town calendar, not with Salt Lake’s April 26.

USU’s planting table also lists suggested sowing windows by group for each city, and it marks some high-elevation plantings as needing protection. Use the calculator on the Extension site for the crop-by-crop dates. This page will not restate a hundred-row table. It turns the frost column into a year.

Two tracks

Valley track. Salt Lake, Ogden, the warmer Provo site, Moab, and St. George. Hardy crops go out weeks before the average last frost, once soil can be worked.

Tender crops cluster around that average. Very tender crops wait until the weather is summer-like. St. George and Moab are long, hot seasons.

The limit there is heat and wind, not a June frost. Choose bolt-resistant greens for summer and do not copy a Park City pea schedule into a May desert.

High track. Park City, Heber, Coalville, Woodruff, and any bench that behaves like them. The average last frost is June or late May. Cool-season crops are the garden.

Tomatoes need a short cultivar and a cover, or they need to be a hobby you can afford to lose. Woodruff’s June 26 average, in USU’s table, is a mountain season. Plant it like one.

February and March

St. George can be planting hardy crops and setting out early transplants while northern valleys are still frozen.

Do not let a St. George video set your Logan weekend.

In the Salt Lake and Utah valleys, March is for starting onions, brassicas, and later peppers indoors, and for working soil only when it crumbles. A wet clay in the valley is the same brick as Front Range clay. The clay page applies.

April

Valley track: sow peas, spinach, lettuce, and radish as soon as the soil allows. Salt Lake’s airport average of April 26 means hardy sowings often belong in early April, and a cautious gardener still owns a cover.

Set brassicas out after hardening. Do not set tomatoes out on the first 75°F day. The 2019 note is written because people do exactly that and then lose them.

High track: April is indoor-seed and soil-prep month. Snow and frozen ground are still plausible. Start the transplants you will set out in late May or June, not a tomato you will hold, root-bound, until July.

May

Valley track: this is the tender-crop month. Around the airport dates in late April and early May, sow beans and squash, and set tomatoes after you are willing to cover a late night or after the local risk has clearly passed. Provo airport’s May 21 and Logan Southwest Farm’s May 23 are the reminder that “May” is not one week. Use your row.

High track: sow hardy crops if the soil is workable, especially in towns whose average is still in June. Potatoes can go in two to three weeks before that average, following the same mountain logic CSU uses, which fits these valleys even though the citation is Colorado’s. Wait on tomatoes.

June

Valley track: the garden is in. Mulch, trellis, and start successive lettuce only in partial shade. Watch for codling moth in apples if you have fruit, and use USU’s current timing rather than a fixed calendar spray. Heat is arriving.

High track: June is planting. Heber, Coalville, Park City, and Woodruff are setting hardy crops and, at the end of the month, maybe a covered tomato. A 92-day season does not fit a long-season melon. Plant the short list.

July and August

Valley gardens harvest and stay ahead of heat stress with even water. A fall broccoli or carrot sowing belongs in the valleys and not, generally, in Woodruff.

High gardens spend July growing the crops they just planted and should be eating greens and peas rather than mourning peppers. Water is still required. High and dry is still dry. Drip on a separate zone from any ornamental xeriscape is the arrangement.

September and October

The 2019 note gives Park City a first frost around September 1. That is an early close. Harvest, cover salads, and do not count on a long pumpkin finish.

Valley first frosts fall much later. USU’s 2019 table lists Ogden’s first frost at October 24 in that particular compilation, with about 176 frost-free days, which is a different season from Park City’s 92.

Use the fall date from the same note as the spring date, and do not mix sources to invent a day count. Plant garlic as soil cools, earlier in the high valleys. Drain irrigation.

November through January

Order seed. Service fruit trees. Check the fence. Resist planting warm-season crops in a St. George winter just because a national feed said “zone 8,” unless you actually garden in Washington County and know the winter.

The Wasatch plant page covers the ornamental side of this split.

Checklist

• Use the USU city row, not a statewide date.
• Treat campus and airport rows in the same town as different sites.
• Keep a high-track calendar for Park City, Heber, Coalville, and Woodruff.
• Hold tender plants for summer weather in the valleys, and for a cover plus a short cultivar in the high towns.
• Look up crop-group dates in USU’s planting table or calculator before you revise a favorite sowing.
• Record your own last and first frosts for three years.

Sources

• USU Extension, Suggested Vegetable Planting Dates for Utah.
• USU Extension, Wasatch Front planting dates.
• USU Extension, planting-date calculator.
• USU Extension, Fickle Climate Keeps Gardeners Guessing.