When to apply crabgrass pre-emergent in Denver (2027)
Updated October 23, 2026. Live numbers refresh hourly.
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Apply crabgrass pre-emergent in Denver once the top few inches of soil stay at 50–55°F, which is the target Michigan State University research uses, and get it down before soil holds 55°F for four to five days in a row. Today the 0–4 inch soil around Denver, CO averages 61°F and is warming.
- Soil today
- 61°F
- +3.8°F over 7 days
Live data for Denver, CO. Check your own ZIP below for local numbers.
Our picks
Chosen from the research below and the makers' own listings. We haven't lab-tested them.
- Homeowners with a spreader
The Andersons Barricade 0.48% Prodiamine Pre-Emergent (APTDG48BR18A, 18 lb)
5,800sq ft per 18 lb bag (Andersons)
A straight granular prodiamine with no fertilizer, spread with an ordinary broadcast spreader and watered in. Andersons times its spring application to before 4-inch soil reaches 55°F, the same trigger this guide tracks.
- Lawns where timing may slip
Jonathan Green Season-Long Weed Preventer
3rd leafcrabgrass stage it still controls (Jonathan Green)
A granular dithiopyr (Dimension) preventer with no fertilizer. Besides stopping seeds, Jonathan Green says it controls crabgrass that has already come up, to the third leaf stage, which gives some slack if a warm spell beats you to the window.
- Pros and big lawns with a sprayer
Prodiamine 65 WDG
65%prodiamine (DoMyOwn listing)
The concentrated, sprayable form of prodiamine. It's mixed with water and sprayed, which suits people who already own a calibrated sprayer or treat a lot of turf; DoMyOwn lists spring and fall use.
- Pros who want early post control
Dimension 2EW herbicide
5-leafcrabgrass stage it still controls (DoMyOwn)
The liquid, professional form of dithiopyr. DoMyOwn lists it as pre-emergent plus early post-emergent on crabgrass up to the five-leaf stage, with single or split applications.
Side by side
| Pick | Best for | Form | Active ingredient | Covers | Young crabgrass already up | Retailer link |
|---|---|---|---|---|---|---|
| The Andersons Barricade 0.48% Prodiamine Pre-Emergent (APTDG48BR18A, 18 lb) | Homeowners with a spreader | Granular (spreader) | Prodiamine 0.48% | 5,800 sq ft per 18 lb; 12,880 sq ft per 40 lb | No (prevents only) | Check price at Andersons |
| Jonathan Green Season-Long Weed Preventer | Lawns where timing may slip | Granular (spreader) | Dithiopyr (Dimension) | 5,000 sq ft per 10 lb; 15,000 sq ft per 30 lb | Up to the 3rd leaf stage (Jonathan Green) | Check price at Jonathan Green |
| Prodiamine 65 WDG | Pros and big lawns with a sprayer | Water-dispersible granule, sprayed | Prodiamine 65% | 0.185–0.55 oz per 1,000 sq ft (label rate); 5 lb jug | No (prevents only) | Check price at DoMyOwn |
| Dimension 2EW herbicide | Pros who want early post control | Liquid concentrate, sprayed | Dithiopyr 24% (2 lb per gallon) | 0.28–0.73 oz per 1,000 sq ft (label rate); 64 oz jug | Up to the 5-leaf stage (DoMyOwn) | Check price at DoMyOwn |
Forms, active ingredients, coverage and early post-emergent claims are from each maker's page or the linked DoMyOwn listing. A dash means the maker doesn't list it.
The Andersons Barricade 0.48% Prodiamine Pre-Emergent (APTDG48BR18A, 18 lb)
Homeowners with a spreader
A straight granular prodiamine with no fertilizer, spread with an ordinary broadcast spreader and watered in. Andersons times its spring application to before 4-inch soil reaches 55°F, the same trigger this guide tracks.
Why we picked it
- 0.48% prodiamine on Andersons' dispersible granule, which it says breaks down when watered and moves into the soil.
- Andersons lists 30 grass and broadleaf weeds it prevents, including crabgrass, goosegrass, poa annua and henbit.
- Comes in 18 lb (up to 5,800 sq ft) and 40 lb (up to 12,880 sq ft) bags; spreader settings are posted on the product page.
Downsides
- Prevention only: Andersons says it won't eliminate weeds that are already up, and it doesn't prevent dandelions or clover.
- It needs at least 0.2 in of water to activate (Andersons).
- It stops grass seed too. Andersons says to wait at least 4 months before seeding, longer at higher rates.
- Form
- Granular (spreader)
- Active ingredient
- Prodiamine 0.48%
- Covers
- 5,800 sq ft per 18 lb; 12,880 sq ft per 40 lb
- Young crabgrass already up
- No (prevents only)
- Fertilizer
- None
- Model
- Andersons APTDG48BR18A (18 lb)
Jonathan Green Season-Long Weed Preventer
Lawns where timing may slip
A granular dithiopyr (Dimension) preventer with no fertilizer. Besides stopping seeds, Jonathan Green says it controls crabgrass that has already come up, to the third leaf stage, which gives some slack if a warm spell beats you to the window.
Why we picked it
- Contains Dimension (dithiopyr) and no fertilizer, so it can go down on its own schedule (Jonathan Green).
- Jonathan Green says one application lasts 3 to 4 months and suggests early spring plus a second application by the end of May for the whole crabgrass season.
- Sold in 10 lb (up to 5,000 sq ft) and 30 lb (up to 15,000 sq ft) bags.
Downsides
- Wait 90 days after applying before you plant grass seed, and 60 days after seeding before you apply (Jonathan Green).
- Post-emergent control is limited to young crabgrass; other weeds have to be prevented before they germinate.
- Water in about 1/2 in after applying to activate it (Jonathan Green).
- Form
- Granular (spreader)
- Active ingredient
- Dithiopyr (Dimension)
- Covers
- 5,000 sq ft per 10 lb; 15,000 sq ft per 30 lb
- Young crabgrass already up
- Up to the 3rd leaf stage (Jonathan Green)
- Fertilizer
- None
Prodiamine 65 WDG
Pros and big lawns with a sprayer
The concentrated, sprayable form of prodiamine. It's mixed with water and sprayed, which suits people who already own a calibrated sprayer or treat a lot of turf; DoMyOwn lists spring and fall use.
Why we picked it
- 65% prodiamine water-dispersible granule from Quali-Pro (EPA Reg. 53883-429), sold in a 5 lb jug.
- DoMyOwn lists a label rate of 0.185 to 0.55 oz per 1,000 sq ft, so a small jug goes a long way.
- Water in with about 1/2 in of rain or irrigation, per the listing; DoMyOwn gives a 3-year shelf life.
Downsides
- You need a sprayer and have to mix and measure small amounts accurately.
- Prevention only: it doesn't kill weeds that are already up (DoMyOwn).
- DoMyOwn doesn't sell it to Alaska or New York, where it's restricted to licensed applicators.
- Form
- Water-dispersible granule, sprayed
- Active ingredient
- Prodiamine 65%
- Covers
- 0.185–0.55 oz per 1,000 sq ft (label rate); 5 lb jug
- Young crabgrass already up
- No (prevents only)
- Model
- Quali-Pro 83013356
Dimension 2EW herbicide
Pros who want early post control
The liquid, professional form of dithiopyr. DoMyOwn lists it as pre-emergent plus early post-emergent on crabgrass up to the five-leaf stage, with single or split applications.
Why we picked it
- 24% dithiopyr (2 lb active per gallon) from Corteva, EPA Reg. 62719-542.
- Label rate of 0.28 to 0.73 oz per 1,000 sq ft; DoMyOwn says a 1/2 gallon treats 2 to 4 acres.
- Non-staining and low odor, per the listing.
Downsides
- Sold in 64 oz and larger jugs, more than most single lawns need.
- It needs 1/2 in of rain or irrigation, ideally within 7 days (DoMyOwn).
- DoMyOwn doesn't sell it to New York.
- Form
- Liquid concentrate, sprayed
- Active ingredient
- Dithiopyr 24% (2 lb per gallon)
- Covers
- 0.28–0.73 oz per 1,000 sq ft (label rate); 64 oz jug
- Young crabgrass already up
- Up to the 5-leaf stage (DoMyOwn)
- Maker
- Corteva
Why soil temperature beats the calendar on the Front Range
Crabgrass seed responds to soil warmth, not dates. Denver springs swing hard: a week in the 70s can be followed by a foot of wet snow, and soil warms in fits. A fixed date like "April 15" is right some years and two weeks off in others. Watching the 0–4 inch soil temperature tells you where this year actually is.
Michigan State University's guidance is to apply when soil in the top 2 inches is consistently 50–55°F. Their weed-biology material notes germination begins after about four to five days at 55°F. Pre-emergents only stop seeds that haven't sprouted, so the goal is to have the barrier in place just before that point.
| 0–4 in soil temperature | What's happening | What to do |
|---|---|---|
| Below 50°F, steady | Crabgrass seed is dormant | Get product and spreader ready |
| 50–55°F for several days | Germination is close | Apply pre-emergent and water it in per label |
| 55°F for 4–5 days in a row | Germination begins (MSU) | Apply immediately; you may already be late on warm sites |
| 60–70°F | Most germination happens (MSU puts about 80% here) | Pre-emergent no longer stops plants that are up |
Denver-specific timing factors
South- and west-facing slopes, strips along driveways and sidewalks, and lawns against brick walls warm days or weeks earlier than the middle of a shaded yard. These are also where crabgrass shows up first. If you treat in one pass, time it for the warmest areas.
Spring snow doesn't reset the clock as much as it seems. A cold, wet storm drops soil temperature for a few days, but if soil had already held 50°F before the storm, apply as soon as the snow melts and the lawn is walkable. Purdue notes most pre-emergents keep working roughly 60 to 120 days depending on the product, so an early application covers you through the main germination period, which in Denver can run into early summer.
Colorado State University's lawn calendar puts the first spring fertilizer in mid-March to April 1 and says it may not be needed if you fertilized late the previous fall. Many combination "crabgrass preventer plus fertilizer" products put both on at once. If your lawn greened up well, a straight pre-emergent avoids pushing early top growth.
How to use the live numbers
The soil temperature above is a modeled daily mean for the 0–10 cm layer from the NOAA GFS model, refreshed four times a day. For your exact address, look up your ZIP, such as 80013 in Aurora, or open the Denver page. The "days until 55°F" countdown appears from February through June.
Starting February 15, 2027 we also track growing degree days. MSU's window for crabgrass pre-emergent is 250–500 GDD (base 32°F) counted from February 15. When soil temperature and GDD agree, you're in the window.
- Water the product in within the time the label gives; most need about half an inch of rain or irrigation to activate.
- Don't core-aerate after applying; it breaks the barrier.
- If you plan to seed this spring, most pre-emergents will stop grass seed too. Read the label, or seed in late summer instead (see overseeding in Colorado).
Questions
What month do you put down pre-emergent in Denver?
Most years it falls between late March and late April, but go by soil temperature: apply once the top few inches hold 50–55°F, before four to five straight days at 55°F.
Is it too late to apply pre-emergent if crabgrass is already up?
Yes for the plants already up. Pre-emergents stop seeds from establishing; they don't kill existing crabgrass. A later germination flush can still be prevented if you apply now.
Does spring snow wash out pre-emergent?
Snowmelt usually acts like the watering-in the label asks for. Heavy runoff on slopes can move granules, so avoid applying right before a big storm on sloped ground.
Should Colorado Springs apply at the same time as Denver?
Go by your local soil temperature. Higher, cooler sites usually warm later. See our Colorado Springs pre-emergent guide.
Should I use a granular or liquid pre-emergent?
Either works if it goes down before soil holds 55°F. Granulars like Andersons Barricade or Jonathan Green Season-Long Weed Preventer go on with a lawn spreader; Prodiamine 65 WDG and Dimension 2EW are concentrates you mix and spray, sold mainly to pros.
Bottom line
Put crabgrass pre-emergent down once Denver's top few inches of soil hold 50–55°F and before four to five straight days at 55°F (MSU), treating warm south-facing strips first. A straight granular prodiamine or dithiopyr with a home spreader covers most lawns; dithiopyr also controls very young crabgrass if a warm spell beats you. Water it in, don't aerate afterward, and plan any seeding for late summer.
Check price at AndersonsThe Andersons Barricade 0.48% Prodiamine Pre-Emergent (APTDG48BR18A, 18 lb)
Sources
- Michigan State University Extension: Timing crabgrass pre-emergence applications
- Michigan State University: Crabgrass weed biology
- Purdue Extension: Do you get crabby about crabgrass?
- Colorado State University Extension: Lawn Care Basics (7.202)
- The Andersons: Barricade 0.48% prodiamine pre-emergent product page
- Jonathan Green: Season-Long Weed Preventer product page
- DoMyOwn: Prodiamine 65 WDG listing
- DoMyOwn: Dimension 2EW herbicide listing
Soil temperatures: NOAA GFS model, 0–10 cm layer. Snow: NOAA and National Weather Service. See how we measure.