Salt Lake City
Treat broadleaf51°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 16 – Oct 28
Utah Weed Watch · updated Nov 3, 1:18 AM CT
When to apply pre-emergent in Utah
Live soil temperatures for Salt Lake City, Ogden, Provo and St. George, updated every three hours. Weeds sprout by soil temperature, not by the calendar, so the right week moves from year to year.
Most Utah lawns get pre-emergent twice a year: in spring for crabgrass and in fall for winter weeds. In Salt Lake City, Ogden and Provo, cool summers mean fall seeding, so it is spring only there.
Spring pre-emergentNext season
Typically Mar 7 – May 1
Stops crabgrass and other summer weeds before they sprout.
Fall pre-emergentThis season
Typically by Sep 27
Stops winter weeds (annual bluegrass, henbit, chickweed) before they sprout.
Skip it if you are overseeding this fall. Not in Salt Lake City, Ogden and Provo.
Right now · fall pre-emergent season
Treat broadleaf weeds now: Salt Lake City, Ogden and Provo. Winter weeds are germinating — apply now if you haven't: St. George
Soil is 50–58°F now. In fall, dandelions, clover and creeping Charlie pull sugars — and weed killer — down to their roots. Seeding this fall? Skip pre-emergent; it stops grass seed too.
Soil temperature by city
Soil 2 inches down, 5-day average: solid line = the last two weeks, dashed = the six-day forecast. Shaded = below 75°F, where winter weeds sprout — pre-emergent has to be down before the line gets there.
Ogden
Treat broadleaf50°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 11 – Oct 25
Provo
Treat broadleaf50°F↓ cooling
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 14 – Oct 28
St. George
Apply ASAP58°F↓ cooling
Soil has cooled to 75°F, so winter weeds are sprouting. Pre-emergent still stops later flushes.
Winter weeds are sprouting now
Utah pre-emergent calendar
Spring pre-emergent stops crabgrass. The window runs from the typical day soil warms to 50°F to the day it holds 55°F, when crabgrass starts germinating (2016–2025). Fall pre-emergent stops winter weeds: have it down a week before soil usually cools to 75°F, when they start germinating.
| City | Spring pre-emergent (crabgrass) | Fall pre-emergent (winter weeds) |
|---|---|---|
| Salt Lake City | Apr 12 – Apr 28 | None (seeding season) · treat broadleaf Sep 16 – Oct 28 |
| Ogden | Apr 8 – Apr 27 | None (seeding season) · treat broadleaf Sep 11 – Oct 25 |
| Provo | Apr 16 – May 1 | None (seeding season) · treat broadleaf Sep 14 – Oct 28 |
| St. George | Mar 7 – Mar 30 | Apply by Sep 27 |
These are typical-year dates (the median of 2016–2025); any one year can run a couple of weeks earlier or later, which is what the live readings above are for. For your exact yard, check soil temperature by ZIP.
Recommended gear
Fall pre-emergents
Granular or liquid. Follow the label rate, and water it in.
Paid links. As an Amazon Associate, MeasureLawn earns from qualifying purchases.
Amazon
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Scotts Halts Crabgrass & Grassy Weed Preventer
Beginner friendlyPendimethalingranularcovers ~5,000 sq ft / 0.11 ac$24.97as of Nov 2, 10:00 AM UTC · may change
Amazon
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The Andersons Barricade Professional-Grade Granular
Beginner friendly0.48% Prodiaminegranularcovers ~12,880 sq ft / 0.30 ac$79.88as of Nov 2, 10:00 AM UTC · may change
Amazon
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Dimension 2EW (Dithiopyr)
Liquid concentrate; 64 oz half gallon; mix with water and spray
Dithiopyrliquidcovers ~91,428 sq ft / 2.1 ac$158.00as of Nov 2, 10:00 AM UTC · may change
What people in Utah are identifying
We record the state each identification comes from. Utah's list appears here once it has at least 40 identifications spread over 7 or more days — so no single scan stands out. Until then, see the national list, or add yours:
Identify a weed from a photoWeeds to watch in Utah this fall
Questions about Utah
When should I apply crabgrass pre-emergent in Utah?
Put crabgrass pre-emergent down as soil warms to 50°F, before it holds 55°F and crabgrass starts germinating. In a typical year (2016–2025) that window is Apr 12 – Apr 28 in Salt Lake City; Apr 8 – Apr 27 in Ogden; Apr 16 – May 1 in Provo; Mar 7 – Mar 30 in St. George.
When should I apply fall pre-emergent in Utah?
Winter weeds such as annual bluegrass, henbit and chickweed start germinating as soil cools to about 75°F in late summer and fall, and most come up once it is below 70°F. Have fall pre-emergent down before they start: typically by Sep 27 in St. George. Skip it if you are overseeding this fall, because it stops grass seed too. In Salt Lake City and Ogden and Provo, cool summers mean cool-season lawns and fall seeding, so skip fall pre-emergent there and treat broadleaf weeds instead.
What is the soil temperature in Utah right now?
As of Nov 3, 1:18 AM CT: Salt Lake City 51°F, Ogden 50°F, Provo 50°F, St. George 58°F (5-day average, about 2.4 inches down). Treat broadleaf weeds now: Salt Lake City, Ogden and Provo. Winter weeds are germinating — apply now if you haven't: St. George.
How the readings and dates are made, and their limits: Weed Watch method. Soil data: Open-Meteo.com (CC BY 4.0); typical dates: NASA POWER.