Portland
Treat broadleaf51°F↑ warming
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 1 – Oct 29
Maine Weed Watch · updated Nov 3, 1:18 AM CT
When to apply pre-emergent in Maine
Live soil temperatures for Portland, Bangor and Presque Isle, updated every three hours. Weeds sprout by soil temperature, not by the calendar, so the right week moves from year to year.
In Maine, 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 May 6 – May 25
Stops crabgrass and other summer weeds before they sprout.
Fall: no pre-emergentThis season
Treat broadleaf weeds Sep 1 – Oct 29
Fall is seeding season here, and pre-emergent would stop grass seed too.
Right now · fall (seeding season)
Treat broadleaf weeds now: Portland and Bangor. Broadleaf season over: Presque Isle
Soil is 45–51°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.
Bangor
Treat broadleaf48°F↑ warming
Fall is the best time to treat dandelions and clover: they pull weed killer down to their roots.
Broadleaf window Sep 1 – Oct 17
Presque Isle
Done for now45°F→ steady
Done for this year. Spot-treat on a mild day, or wait for spring.
Broadleaf window Sep 1 – Oct 6
Maine 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 Maine 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.
| City | Spring pre-emergent (crabgrass) | Fall (seeding season) |
|---|---|---|
| Portland | May 7 – May 19 | None (seeding season) · treat broadleaf Sep 1 – Oct 29 |
| Bangor | May 6 – May 20 | None (seeding season) · treat broadleaf Sep 1 – Oct 17 |
| Presque Isle | May 14 – May 25 | None (seeding season) · treat broadleaf Sep 1 – Oct 6 |
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 Maine are identifying
We record the state each identification comes from. Maine'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 Maine this fall
Questions about Maine
When should I apply crabgrass pre-emergent in Maine?
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 May 7 – May 19 in Portland; May 6 – May 20 in Bangor; May 14 – May 25 in Presque Isle.
Should I put down pre-emergent in the fall in Maine?
Usually not. Fall is the best time to seed a cool-season lawn in Maine, 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 Maine right now?
As of Nov 3, 1:18 AM CT: Portland 51°F, Bangor 48°F, Presque Isle 45°F (5-day average, about 2.4 inches down). Treat broadleaf weeds now: Portland and Bangor. Broadleaf season over: Presque Isle.
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.