Posts Tagged ‘crabgrass control’

Crabgrass Q & A

Published by mrgrass on April 23rd, 2015 - in Crabgrass

Q. It’s April and my lawn is full of crabgrass, what can I do?

A. Crabgrass is an annual plant and does not even germinate in NH and VT until mid or late May. Any grasses you see now and suspect are crabgrass, are not. They are perennial grasses and may appear to look like crabgrass. This is a very common misperception. Unwanted perennial grasses need special care including manual or herbicide removal.

Q. I always have crabgrass, nothing seems to work, what can I do?

A. Crabgrass generally indicates an underlying problem like unhealthy soil, recent insect damage, or some other event that allow it to flourish rather than your lawn. Although pre-emergent products work great, in the absence of surrounding grass, the barrier will fail and the problem will reoccur year after year. Only by improving the soil and adding superior grass seed into the infected area will you ever conquer this ongoing issue.


Q. I typically dig out crabgrass and weeds, is this doing more harm than good?

A. Whenever you tear up any plant, you bring up more of the weeds’ seeds to the surface where they will germinate. While you may have temporary relief and feel good about removing crabgrass manually, you are actually making the problem worse by depositing seeds that would otherwise have remained dormant buried below.


Q. When is the best time to apply crabgrass control?

A. In NH and VT, there are several types of pre-emergent control products that do a nice job by safely preventing not only crabgrass, but also many annual weeds from germinating in the soil. A pre-emergent is the best product and means to reduce crabgrass. By definition, a pre-emergent must be applied before the crabgrass rears its ugly head! Soil temperature is the big deal here and once mid to late May arrives, you are likely to have crabgrass germinating; especially in sunny locations like along your driveway, walkways, or roadside. Once crabgrass germinates and while still small, in the two or three leaf stage, there are other products that can be used to still gain control. For larger crabgrass, you would need to switch to yet another specialized material for use through August. Once fall rolls around, just let this annual plant die off. However, the best way to prevent crabgrass is with a thick healthy lawn created with healthy soil, adequate nutrition, and by mowing at the proper height (2” first cut of the season, 3” May – September).

See my blog for information on crabgrass.


Crabgrass in your lawn

Published by JKeefe on July 21st, 2010 - in Crabgrass, Lawn Care Companies

There are many factors which yield a high crabgrass population in any given lawn area.  Last season, we had one of the wettest seasons in nearly a decade while this year we are in one of the hottest in nearly a decade.  The two extremes are just that- extreme and there are ramifications to a lawn.  To understand what happens in a lawn setting we must look at the weather, turf density, mowing height, and treatments.  Hot and especially dry weather will cause dormant crabgrass seed to germinate- typically in bare areas first (along roads, walkways, driveways) followed by thin sections in the lawn.  Crabgrass loves high heat and low moisture.  Seeds can remain dormant for years until the right conditions arrive, and then they germinate.  Normal rain, proper fertilization, and cutting height can usually minimize crabgrass in primary lawn areas.  Grass that has been treated with high soluble fertilizers and is not as healthy will be more susceptible to crabgrass infiltration.  The best defense is still a thick lawn, a high cut, irrigation if possible, and slow release fertilizer among other applications.  Some years are above or below average in terms of rainfall and heat- key factors in crabgrass germination.

Crabgrass plant

One year of crabgrass does not undo a lawn.  A pre-emergent barrier can be applied in the spring, but even that will degrade by late July or early August.  Luckily, crabgrass knows when the remaining growing season is insufficient to complete its life cycle.  Said another way, crabgrass seeds will usually not germinate past mid July.  So what you see now is going to be it- the plants will just become larger.  Again, a pre-emergent barrier can be used to help suppress, not eliminate crabgrass in thin or weak areas.  Most of these products are simply dyes and are not harmful in terms of the environment.  A pre-emergent product can be applied this fall (often overlooked) or next spring if you belive crabgrass has gotten a firm foothold in your lawn.  There is a trade off between putting down a barrier and seeding- so give this treatment careful consideration.  When desirable turf becomes stressed by high heat and drought, it provides an ideal growing environment for crabgrass by heating up the soil.  Lack of moisture further stresses desirable turf and enhances the ability of crabgrass to grow at exponential rates- real fast.

Mowing at 3”, mulching clippings, watering (1” per week), and a solid lawn health care program are all great defensive measures.  Adding a pre-emergent in the spring is another tool to help inhibit crabgrass but not eliminate it.  In a normal year, things would be in check and balance like in nature.  However, in extreme heat and drought- nature will win the battle and aesthetics will suffer- regardless of the plans in place.

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