Crabgrass is a pesky annual weed that needs to be prevented early in the season. There are a number of crabgrass killers on the market, but applying a split application of pre-emergents in the early and late spring can limit the need for any post emergent herbicides. That’s why controlling crabgrass is one of the first things for cool season lawn care nuts to do to establish a healthy lawn.
Crabgrass seeds will begin to germinate when the soil temperatures reach approximately 55 degrees. A good rule of thumb is when you see the forsythia in bloom, the crabgrass is germinating. Without proper pre-emergent herbicides, crabgrass will continue to germinate throughout the spring and early summer months as the ground temps approach 70 degrees.
The best mode of action is by applying an application of crabgrass preventer in early spring (e.g. Prodiamine in early April in New England) and a second pre-emergent application in early June. These pre-emergents form a vapor barrier that inhibits the crabgrass rooting from taking place.
There’s a number of different crabgrass preventers on the market, from granular to liquids. Here is a list of the Top-5 crabgrass pre-emergent herbicides .
Prodiamine is the king of crabgrass prevention. This 45 lbs. bag of Yard Mastery 0-0-7 Prodiamine 0.38% will cover 15,000 sq. ft. They also sell as 24 lbs. bag of Prodiamine which covers 8,000 sq. ft. This does not contain any fertilizer other than 7% Potassium, which is mainly used as a carrier.
Apply this crabgrass pre-emergent in the early spring as soil temperatures approach 50 degrees. Water this in with 1/2″ of water immediately for best results. I’ve been applying a 0-0-7 Prodiamine for my first pre-emergent application in early spring (first week of April here in Massachusetts) with great success. I personally don’t apply pre-emergents with fertilizers (N-P-K) this early because the turf isn’t quite ready to be pushed, especially if you prepared your lawn for winter and applied a winter fertilizer app. However they’re a great choice for your second or third split application (more below).
Please note that there is a maximum annual rate of Prodiamine per calendar year. So if you plan on using this in early april to prevent crabgrass, and in the fall to control poa annua, keep this chart handy (cool season grasses listed only):
|GRASS TYPES||LBS./ 1,000 SQ. FT PER YEAR|
|Tall Fescue||9 lbs.|
|Kentucky Bluegrass||6 lbs.|
|Creeping Red Fescue||4.5 lbs.|
|Creeping Bentgrass||3.9 lbs.|
For a second split application of crabgrass pre-emergent, a fertilizer-herbicide combo has been on my calendar – and The Andersons 21-0-10 with 0.25% Dimension is a great choice. About 8 weeks after your first Prodiamine application is when your second herbicide application can be applied. At this time, the soil temps are warmer and the grass is growing like crazy. The best time to apply this in New England would be in early June.
The 21% nitrogen is all urea, which means you will get a very fast release and quick “pop”, and the 10% Soluble Potash (K20) may help with the upcoming summer stress. Secondly, Dimension (Dithiopyr) has post emergent qualities which can kill younger crabgrass. That’s what makes Dimension a great choice at this time of year.
Andersons Application Rates according to the label:
Use Program 1 for preemergence control at sites where the turfgrass is cut high (e.g., homeowner lawns). This program provides 3-5 months of preemergence crabgrass control. This program should not be used for early postemergence crabgrass control.
Use Program 2 for preemergence control at sites where (a) turfgrass is cut low (e.g., golf fairways) and (b) turfgrass maintenance or weed control has been conducted during the previous year. This program provides 4-6 months of preemergence crabgrass control. This program may also be used for early postemergence control at sites where turfgrass is cut high (e.g., homeowner lawns).
Use Program 3 for preemergence control at sites where (a) turfgrass is cut low (e.g., golf fairways), and (b) turf maintenance or weed control has not been conducted during the previous year. This program provides 4-6 months of preemergence crabgrass control. This program may also be used for early postemergence control at sites where turfgrass is cut low (e.g., golf fairways)
|PROGRAM||Program 1||Program 2||Program 3|
|Northern||1.2 lbs.||1.7 lbs.||2.3 lbs.|
|Transitional||1.7 lbs.||2.3 lbs.||3.4 lbs.|
|South||2.3 lbs.||3.4 lbs.||4.6 lbs.|
|Coastal South||3.4 lbs.||4.6 lbs.||4.6 lbs.|
Dimension 2EW is a great liquid option as it provides excellent pre-emergent control of crabgrass. This product can also control other annual grassy weeds such as Poa Annua, Dallisgrass and Goosegrass, and even broadleaf weeds like Chickweed, Purslane, and Spurge. And like The Andersons with Dimension, 2EW can also kill crabgrass in the early stages.
The application rates for Dimension 2EW 0.28-0.73 oz. per gallon per 1,000 sq. ft. Do not apply more than 0.73 oz. f Dimension 2EW per 1,000 sq. ft. per application, and no more than 6 pints of Dimension 2EW per acre per year (2.2 fl oz per 1000 sq ft).
The cost for 64 oz. container comes to $2.28 per ounce ($146 for 1/2 gallon at the time of this published date) which equates to $0.64 – $1.66 per 1,000 sq. ft. After spraying Dimension 2EW herbicide, water in with 1/2″ of irrigation or rainfall within 6 hours of application.
Use our free Dimension Calculator to get your application right.
Prodiamine 65WDG is the best option for crabgrass preventers for those on a budget. Quali-Pro is a reputable company that makes highly-effective products at a very affordable price. Their products are generic versions of the more expensive brand names – this one being generic Barricade. The “65” refers to the 65% active ingredient, prodiamine; the “WDG” means Wettable Dispersible Granule which is easily mixed and dissolved in water to make a liquid sprayable herbicide.
In addition to controlling large crabgrass and smooth crabgrass, Prodiamine 65WDG is labeled to also control Foxtails, Henbit, Johnsongrass, Woodsorrel and more.
This 5 lbs. container can cover just over an acre at low rates. Below is a table of the Prodiamine 65WDG application rates for cool season lawns. You can also use our free Prodiamine Calculator to make sure that you get your application right.
|GRASS TYPE||OZ. PER ACRE||OZ. PER 1,000 sq. ft||SQ. FT. COVERAGE|
|Tall Fescue||1.0 – 2.3||0.36 – 0.83||22,000 – 9,600|
|0.5 – 1.5||0.185 – 0.55||44,000 – 14,700|
|Fine Fescue||0.5 – 1.15||0.185 – 0.42||44,000 – 19,100|
|Creeping Bentgrass||0.5 – 1.0||0.185 – 0.37||44,000 – 22,000|
To finish of this list of the best crabgrass pre-emergent herbicides and preventers is Pendulum 2G. This herbicide contains an active ingredient Pendimethalin – which is the same chemical that is found in Scott’s Halts.
For 2-4 months of coverage, apply Pendulum 2G at rates of 2.3 lbs. per 1,000 sq. ft. For longer coverage (6-8 months) apply up to 4.6 lbs. per 1,000 sq. ft. per application. At these rates, a 40 lbs. bag will cover between 8,700 – 17,400 sq. ft. of turf grass. Pendulum 2G also controls the emergence of both grassy weeds and broadleaf weeds such as Oxalis, Poa Annua, Purslane and many more.
It is important to know that these products will affect your grass seeds from germinating, too. Whether you’re overseeding a lawn or filling in some bare spots, applying these products will not just prevent crabgrass and other weeds, but also your good grass, too. Consider using Tenacity (Mesotrione) when spring seeding to help prevent emerging crabgrass.
Prodiamine (Barricade) Pros
- Long lasting – up to 9 months efficacy
- Inexpensive (particularly generic)
- Best to apply early in the season
- Great crabgrass control
Prodiamine (Barricade) Cons
- Needs to be watered in quickly
- Will lose a lot of efficacy if not watered in within 14 days
- Not a great broadleaf weed control
- Breaks down with exposed sunlight (photodegradation)
- Note for aeration and overseed: it’s a good to lower your height of cut (HOC) a couple of weeks prior to allow more sunlight to the soil. This will help ensure the pre-emergent is out of the soil
Dithiopyr (Dimension) Pros
- Better than Prodiamine at preventing broadleaf weeds
- Post emergent qualities that can kill younger crabgrass
- Apply later in the season – great option for your second/third of your split application
Dithiopyr (Dimension) Cons
- Root pruner of good grass (KBG, TTTF, PRG)
- Ensure roots are well-established before applying
- More expensive than Prodiamine
- Less efficacy than Prodiamine (3-4 months)
- Takes higher rates to control crabgrass
- Breaks down more so with water and heat
Crabgrass Pre-Emergent FAQ’s
The best mode of action to prevent crabgrass is by applying a split application of pre-emergents. The first application of Prodiamine or Pendimethalin should be applied in early spring before soil temperatures reach 55 degrees. The second application should be applied approximately 8 weeks after. In Massachusetts for example, this would be in early April and early June.
Depending on the product and application rates, crabgrass pre-emergents can last between 2-3 months at low rates, to upwards of 8-9 months at maximum rates. It is important to water in these herbicides with 1/2″ of water immediately after applying.
Scott’s Halts contains the active ingredient, Pendimethalin. At max rates, Pendimethalin can last up to 8 months. The best time to apply this pre-emergent is early spring before soil temperatures hit 55 degree – just as the forsythia bloom.
Yes. Many pre-emergents also contain fertilizer all-in-one. Many Step 1 fertilizers will contain high rates of Nitrogen and lower Potassium numbers with a crabgrass preventer. If you apply in early spring, you may want to skip the fertilizer until later when the grass begins to actively grow. For applications in late spring and early summer, an all-in-one like 20-0-10 is a great choice.
You will want to look for selective herbicides that have the following active ingredients:
Pendimethalin (Pendulum, Halts)