Fall in zone 6bPhoto: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons
Frost dates for ZIP 84109 (Millcreek, UT)
Average last spring and first fall frost dates with 10%, 50% and 90% odds, from NOAA's 1991–2020 climate normals for the nearest weather station, Mtn Dell Dam, UT (3 miles away).
- Average last spring frostMay 750% chance of a 32°F freeze after this date
- Average first fall frostOct 1450% chance of a 32°F freeze by this date
- Growing season (frost-free)158 daysmedian, 32°F threshold
- USDA hardiness zone6b-5 to 0°F avg. coldest night
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This week in your yard
As of Oct 18, 2026, from your frost dates, zone and soil temperature. Lawn timing · Vegetables · Pruning · Plants
Soil temperature now
2-inch depth
50°F 50–55°F
24-hour average · latest 48°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Morgan (20 mi), Grantsville (37 mi), Chicken Ridge (48 mi).
4-inch depth
51°F 50–55°F
24-hour average · latest 50°F, as of Oct 18, 2:00 AM CDT
Estimate Not a measurement at this ZIP: distance-weighted average of Morgan (20 mi), Grantsville (37 mi), Chicken Ridge (48 mi).
Fall: Texas A&M AgriLife times fall pre-emergent (for winter weeds such as annual bluegrass) to soil cooling to about 70°F for several days. The 50–55°F band is the spring trigger. Always read and follow the product label.
7-day forecast and frost risk
The latest National Weather Service 7-day forecast and any Frost Advisory or Freeze Warning for 84109 load here. You can also open the NWS forecast for this ZIP.
Pre-emergent
Soil is 51°F at 4 inches (estimated soil temperature, not a station reading). Fall pre-emergent window is mostly past. Next: spring, when soil reaches 50°F (typically mid-April to mid-May).
Fertilizer window
Lawn region: Mountain West and High Plains. Timing only; always follow the product label.
- Kentucky bluegrass (cool-season): Early fall: Around Labor Day (late August–September); Late fall: Late October–November, before the ground freezes; Late spring: Optional around Memorial Day. Avoid: Early-spring and midsummer feeding (pushes top growth, favors crabgrass).
Plant now
No vegetable planting windows are open this week.
Prune now
No frost-timed pruning windows are open this week.
Spring-flowering shrubs are pruned right after their flowers fade, not by date. See the pruning guide.
Last spring frost odds
| Chance of a 32°F freeze after this date | Date |
|---|---|
| 90% (early: most years still freeze after this) | Apr 21 |
| 50% (the "average" last frost) | May 7 |
| 10% (cautious: only 1 year in 10 freezes later) | May 27 |
Most gardeners plant frost-tender crops (tomatoes, peppers, basil) after the 50% date, and closer to the 10% date for less risk.
First fall frost odds
| Chance the first 32°F freeze has happened by this date | Date |
|---|---|
| 10% (early: 1 year in 10 freezes this soon) | Sep 29 |
| 50% (the "average" first frost) | Oct 14 |
| 90% (late: most years have frozen by now) | Oct 27 |
Light frost, freeze and hard freeze
| Threshold | Last spring (50%) | First fall (50%) |
|---|---|---|
| 36°F (light frost possible on clear, calm nights) | May 25 | Oct 1 |
| 32°F (freeze) | May 7 | Oct 14 |
| 28°F (hard freeze) | Apr 21 | Oct 26 |
n/a means NOAA did not publish a date at that threshold for this station (usually because it rarely gets that cold).
Vegetable planting calendar for 84109
Dates count from your average last spring frost (May 7) and first fall frost (Oct 14). Half of years have a frost after the spring date, so give tender crops (tomatoes, peppers, squash) some slack.
| Crop | Start indoors | Spring planting | Fall planting |
|---|---|---|---|
| Tomato | Mar 12–26 | May 14–28 (transplant) | – |
| Pepper (sweet and hot) | Feb 26–Mar 12 | May 21–Jun 4 (transplant) | – |
| Eggplant | Feb 26–Mar 12 | May 21–Jun 4 (transplant) | – |
| Tomatillo | Mar 12–26 | May 14–28 (transplant) | – |
| Lettuce | Mar 12–26 | Apr 16–May 7 (transplant) Apr 9–May 21 (sow outdoors) | Aug 19–Sep 9 (transplant) Aug 5–Sep 2 (sowing) |
| Spinach | – | Mar 26–Apr 16 (sow outdoors) | Aug 19–Sep 9 (sowing) |
| Kale | Mar 12–26 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | Jul 22–Aug 19 (transplant) Jul 8–Aug 5 (sowing) |
| Collards | Mar 12–26 | Apr 9–May 7 (transplant) Apr 9–May 7 (sow outdoors) | Jul 22–Aug 19 (transplant) Jul 8–Aug 5 (sowing) |
| Broccoli | Feb 26–Mar 12 | Apr 9–23 (transplant) | Jul 8–Aug 5 (transplant) |
| Cabbage | Feb 26–Mar 12 | Apr 9–23 (transplant) | Jul 8–Aug 5 (transplant) |
| Cauliflower | Feb 26–Mar 12 | Apr 23–May 7 (transplant) | Jul 8–Aug 5 (transplant) |
| Brussels sprouts | Feb 12–26 | Apr 9–23 (transplant) | Jun 24–Jul 15 (transplant) |
| Kohlrabi | Mar 12–26 | Apr 9–23 (transplant) Apr 9–23 (sow outdoors) | Aug 5–19 (sowing) |
| Bok choy / Asian greens | – | Apr 9–23 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Arugula | – | Apr 9–May 7 (sow outdoors) | Aug 19–Sep 16 (sowing) |
| Mustard greens | – | Apr 9–30 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Swiss chard | Mar 26–Apr 9 | Apr 23–May 14 (transplant) Apr 23–May 21 (sow outdoors) | Aug 5–19 (sowing) |
| Beet | – | Apr 9–May 7 (sow outdoors) | Aug 5–19 (sowing) |
| Carrot | – | Apr 16–May 14 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Radish | – | Apr 2–May 14 (sow outdoors) | Sep 2–16 (sowing) |
| Turnip | – | Apr 9–30 (sow outdoors) | Aug 5–19 (sowing) |
| Parsnip | – | Apr 16–May 7 (sow outdoors) | – |
| Pea (garden, snap, snow) | – | Mar 12–Apr 9 (sow outdoors) | Jul 22–Aug 5 (sowing) |
| Onion (bulbing) | Feb 12–26 | Mar 26–Apr 9 (transplant) | – |
| Green onion / scallion | – | Mar 26–Apr 23 (sow outdoors) | Aug 5–19 (sowing) |
| Leek | Feb 12–26 | Apr 9–23 (transplant) | – |
| Garlic | – | – | Sep 2–30 (sowing) |
| Shallot | – | Mar 26–Apr 9 (transplant) | Sep 2–30 (sowing) |
| Potato | – | Apr 9–23 (transplant) | Jun 24–Jul 8 (transplant) |
| Sweet potato | – | May 28–Jun 11 (transplant) | – |
| Sweet corn | – | May 14–28 (sow outdoors) | – |
| Bean, bush (snap) | – | May 14–28 (sow outdoors) | – |
| Bean, pole | – | May 14–28 (sow outdoors) | – |
| Lima bean | – | May 21–Jun 4 (sow outdoors) | – |
| Southern pea (cowpea, black-eyed pea) | – | May 28–Jun 18 (sow outdoors) | – |
| Cucumber | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Summer squash / zucchini | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Winter squash | Apr 9–16 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Pumpkin | – | May 14–28 (sow outdoors) | – |
| Watermelon | Apr 9–16 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Cantaloupe / muskmelon | Apr 9–16 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Okra | Mar 26–Apr 9 | May 21–Jun 4 (transplant) May 21–Jun 4 (sow outdoors) | – |
| Celery | Feb 12–26 | May 14–21 (transplant) | – |
| Basil | Mar 26–Apr 9 | May 14–28 (transplant) May 14–28 (sow outdoors) | – |
| Cilantro | – | Apr 23–May 21 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Parsley | Feb 26–Mar 12 | Apr 23–May 7 (transplant) Apr 16–May 7 (sow outdoors) | – |
| Dill | – | May 7–21 (sow outdoors) | Aug 19–Sep 2 (sowing) |
| Sunflower | – | May 7–21 (sow outdoors) | – |
| Asparagus (crowns) | – | Apr 9–23 (transplant) | – |
| Rhubarb (crowns) | – | Apr 9–23 (transplant) | – |
| Strawberry (plants) | – | Apr 9–23 (transplant) | Aug 5–Sep 2 (transplant) |
Typical ranges from university extension planting calendars, adjusted to your frost dates. Probabilities, not guarantees. Fall windows that would overlap spring planting are left out, as are fall crops of frost-tender plants where the frost-free season is under 210 days.
Where these numbers come from
Station: Mtn Dell Dam, UT (NOAA GHCN-Daily ID USC00425892), elevation 5,420 ft, 3.1 miles from the ZIP's center point. NOAA completeness flag: R (representative, 10+ years).
Nearby stations
| Station | Distance | Last frost (50%) | First frost (50%) |
|---|---|---|---|
| Salt Lake City E Bench, UT | 6 mi | Apr 25 | Oct 18 |
| Cottonwood Weir, UT | 7 mi | Apr 29 | Oct 22 |
| Alta, UT | 9 mi | Jun 11 | Sep 18 |
The average last-frost dates of these stations span 48 days, a rough guide to local variation. See data sources & methods.
Frost questions for 84109
When is the last frost in 84109?
The average (50% chance) last spring freeze of 32°F for ZIP 84109 is May 7. For a more cautious planting date, use May 27, when only 1 year in 10 still sees a later freeze.
When is the first frost in 84109?
The average first fall freeze is October 14. In 1 year in 10 it comes by September 29.
What hardiness zone is 84109?
ZIP 84109 is in USDA zone 6b (-5 to 0°F average coldest winter night), per the 2023 USDA Plant Hardiness Zone Map ZIP listing.
What is the soil temperature in 84109 right now?
This page shows the latest 2-inch and 4-inch soil temperature from the nearest public soil station (USDA SCAN, NOAA USCRN or TexMesonet), or a labeled estimate when no station is close, against the 50–55°F spring pre-emergent band.
Nearby ZIP codes
84124 Millcreek 84121 Brighton 84108 Emigration Canyon metro township 84117 Holladay 84113 Salt Lake City 84106 Salt Lake City 84112 Salt Lake City 84105 Salt Lake City
Other ZIP codes in Salt Lake County
84006 84009 84020 84044 84047 84065 84070 84081 84084 84088 84092 84093 84094 84095 84096 84101 84102 84103 84104 84105 84106 84107 84108 84111 All Salt Lake County frost dates · Utah frost dates
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Free. One weekly email plus alerts when your ZIP has a frost or a soil-temperature change worth acting on. After you submit, Kit (our email provider) sends a confirmation email: check your email and click the link to confirm. You aren't subscribed until you do. We collect only your email address and ZIP, sent to Kit to deliver The Dial. Unsubscribe anytime.