Minnesota Weed Watch · updated Nov 3, 1:18 AM CT

When to apply pre-emergent in Minnesota

Live soil temperatures for Minneapolis, Rochester, St. Cloud and Duluth, updated every three hours. Weeds sprout by soil temperature, not by the calendar, so the right week moves from year to year.

In Minnesota, pre-emergent is a spring job: it stops crabgrass. Fall is seeding season here, so fall weed control means treating broadleaf weeds instead.

Spring pre-emergentNext season
Typically Apr 25 – May 26
Stops crabgrass and other summer weeds before they sprout.
Fall: no pre-emergentThis season
Treat broadleaf weeds Sep 1 – Oct 24
Fall is seeding season here, and pre-emergent would stop grass seed too.
Right now · fall (seeding season)
Treat broadleaf weeds now: Minneapolis and Rochester. Broadleaf season over: St. Cloud and Duluth

Soil is 49–55°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.

Minneapolis

Treat broadleaf
55°F↓ cooling

Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.

today

Broadleaf window Sep 1 – Oct 24

Rochester

Treat broadleaf
55°F↓ cooling

Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.

today

Broadleaf window Sep 1 – Oct 18

St. Cloud

Done for now
52°F↓ cooling

Done for this year. Spot-treat on a mild day, or wait for spring.

today

Broadleaf window Sep 1 – Oct 12

Duluth

Done for now
49°F↓ cooling

Done for this year. Spot-treat on a mild day, or wait for spring.

today

Broadleaf window Sep 1 – Oct 10

Minnesota 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). In fall Minnesota lawns are in seeding season, so there is no fall pre-emergent; the window shown is for treating broadleaf weeds instead, from September until two weeks after soil usually cools to 55°F.

CitySpring pre-emergent (crabgrass)Fall (seeding season)
MinneapolisApr 25 – May 11None (seeding season) · treat broadleaf Sep 1 – Oct 24
RochesterApr 25 – May 12None (seeding season) · treat broadleaf Sep 1 – Oct 18
St. CloudMay 4 – May 11None (seeding season) · treat broadleaf Sep 1 – Oct 12
DuluthMay 13 – May 26None (seeding season) · treat broadleaf Sep 1 – Oct 10

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.

What people in Minnesota are identifying

We record the state each identification comes from. Minnesota'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 photo

Weeds to watch in Minnesota this fall

Dandelionfall is the best time to treat · how to treat →White clovertreat while still growing · how to treat →Creeping Charlieneeds triclopyr; fall works best · how to treat →

Questions about Minnesota

When should I apply crabgrass pre-emergent in Minnesota?

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 25 – May 11 in Minneapolis; Apr 25 – May 12 in Rochester; May 4 – May 11 in St. Cloud; May 13 – May 26 in Duluth.

Should I put down pre-emergent in the fall in Minnesota?

Usually not. Fall is the best time to seed a cool-season lawn in Minnesota, and pre-emergent stops grass seed as well as weeds. Fall is the time to treat broadleaf weeds such as dandelion, clover and creeping Charlie, once the summer heat breaks and while they are still growing.

What is the soil temperature in Minnesota right now?

As of Nov 3, 1:18 AM CT: Minneapolis 55°F, Rochester 55°F, St. Cloud 52°F, Duluth 49°F (5-day average, about 2.4 inches down). Treat broadleaf weeds now: Minneapolis and Rochester. Broadleaf season over: St. Cloud and Duluth.

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.