Crabgrass vs Tall Fescue

Crabgrass vs Tall Fescue admin February 21, 2023


How to tell if crabgrass or fescue is taking over your lawn

All too often coarse tall fescue is incorrectly identified as crabgrass.Tall fescue is a thick-bladed perennial grass that usually grows in clumps in the middle of a lawn. Until 2024, tall fescue was not selectively controllable and could only be killed with a non-selective vegetation control like Glyphosate.  Fortunately, there is now a way to control tall fescue using a special application technique using a weed control called Tenacity.

Crabgrass vs Coarse Fescue

Crabgrass is much easier to control than tall fescue because it is an annual grass. One of the easiest ways to tell the difference between tall fescue and crabgrass is based on the time of year it germinates.  Crabgrass typically germinates during the month of May and will show up in a lawn sometime around the middle of June or early July.


Crabgrass is also easily identified by its light green color and crabgrass usually grows on the edges or in thin / stressed areas of the lawn. People are often misinformed and are under the impression that crabgrass is only controllable using a pre-emergent control. Crabgrass, however, is easily controlled using a special post-emergent crabgrass killer called Drive XLR8. Crabgrass can be killed without damaging your desirable grasses. The crabgrass will die between 3-10 days after the application.

Examples of Crabgrass

Crabgrass Fort Collins Colorado
This is young crabgrass, which is an annual grass that germinates in late June or early July and is easily controlled using Drive XLR8.
Late June or July is the best time of year to kill this annual grass. It is best to treat this grass in the early stages, before it spreads seeds.
Mature Crabgrass
This is an example of mature crabgrass. At this stage the crabgrass has already developed seeds and is more difficult to control compared to young crabgrass.

Examples of Coarse Tall Fescue

Coarse fescue in lawn
There are a number of types of coarse tall fescue grasses and this is an example of this ugly clumping grass.
Coarse Tall Fescue
This grass type is not to be confused with turf-type tall fescue, which is an attractive tall fescue blend.
This is coarse fescue in a bluegrass lawn. We can spot treat this grass with a special treatment without harming the bluegrass.

Crabgrass vs. Fescue Quick Reference:

  • Crabgrass is an annual grass that is lime-green or lighter colored and typically appears in the lawn sometime between the middle of June and early July.
  • Crabgrass can easily be controlled with one application using Drive XLR8. Note that Drive XLR8 is also an excellent bindweed killer.
  • Coarse fescue is a thick-bladed perennial grass that is dark green, very drought tolerant, and grows in the lawn all year long.
  • Brome grass / pasture grasses are lighter colored thick-bladed grasses that are often seen in native areas and pastures.  When they move into a lawn they can be seen all year long.
  • Coarse tall fescues / brome grasses / pasture grasses can be selectively controlled with back-to-back-to-back applications using a special application technique and a product called Tenacity.

If you have crabgrass or coarse tall fescue growing in your Boulder or Fort Collins area lawn, call Organo-Lawn today and schedule an application to kill those grasses.

How to Control Crabgrass

Drive XLR8 is a fast-acting selective control that will kill the crabgrass post-emergently and the crabgrass will typically die between 3-10 days after the application.  

How to Control Coarse Tall Fescue

Controlling coarse fescues, native grasses, and brome grasses has not been possible until 2024.  Previously, the only way to control coarse bladed perennial grasses was to kill them selectively using a product like Glyphosate (RoundUp) and then reseeding the area that was killed.  Fortunately, there is a now an option to kill the coarse bladed grasses without killing the desirable grasses.

The process is back-to-back-to-back applications using a special weed control called Tenacity.  We have found that we can achieve a 50-90%+ control rate.  We have found that higher control rates occur on the grasses that look more like field grasses.  The lesser control rates occur on grasses that look more like turf grasses.  Basically, if the coarse grasses are a hybrid of coarse grass and turf grass the control rate will decrease.

Drive XLR8 Information

Crabgrass and Bindweed Killer Information Sheets




Drive XLR8 weed and crabgrass killer is registered with the EPA by BASF, EPA reg. #7969-272. This post-emergent crabgrass and bindweed killer is also registered with the Colorado Department of Agriculture.

Tenacity Information

Coarse Fescue Killer Information Sheets




Tenacity is registered with the EPA reg. # 100-1267. Tenacity is also registered with the Colorado Department of Agriculture.