Don’t Undo the Effectiveness of Your Crabicide Application

Before getting into the details of my 4th tip, it’s important that the homeowner understand a few things here. The first thing is that crabgrass is an annual plant; any time it is exposed to freezing temperatures it is going to die. Another thing is that every year crabgrass starts new from seed - and these seeds are already in your soil. They are extremely tiny, and research has shown that they can survive alive but dormant in the soil for many, many decades until the conditions are right for them to sprout.

For example, in the Springtime there may be an unusually warm period during which crabgrass seeds can sprout. But if after several days of this warm weather the temperatures should drop again below freezing, all the new crabgrass seedlings are going to die. The point here is that in early Spring when temperatures are still dropping below freezing (even if only overnight), you still have Mother Nature protecting your lawn against the emergence of crabgrass. Once temperatures no longer drop below freezing, crabgrass can sprout and may begin to take over your lawn.

So if you’re trying to prevent crabgrass, it is important to apply a pre-emergent crabicide while temperatures are still occasionally dropping below freezing because this chemical only kills crabgrass sprouts in their earliest stages. If crabgrass has started to establish itself, it is the freezing temperatures that will kill it, not the pre-emergent crabicide. But once this chemical is down, crabgrass cannot establish itself - if it hasn’t already - regardless of the temperature.

One more bit of information here. The chemical barrier that pre-emergence crabicide leaves at the surface of the soil can be destroyed with heavy raking. In other words, heavy raking should be avoided after an application of this crabicide, as this has a tendency to undo much of the protection that the crabicide was offering.

If any of the above seems confusing to you, just remember this: do your heavy raking early, apply the crabicide, and then do not do any more heavy raking until the Fall.

NEXT TIME: When You Absolutely Positively Should Not Use Pre-Emergent Crabicide