Question to landscapers

[Alex Berkovsky]

I am paying a landscaper to maintain my lawn. Recently I noticed that the front lawn has a lot of crabgrass growing. I called the landscaper to find out why it's growing if they applied crabgrass preventer earlier in the season. His answer was that it's because we had a lot of rain recently. Sounds like BS to me. Is it?

[Jim Becker]

Depends. Early in the season was a long time ago. How short are they cutting the lawn? When is the last time it was aerated and over-seeded? Weeds like crabgrass are "opportunistic" and thrive more when there is plenty of light to help their seeds germinate. A rich, thick lawn is less likely to let crabgrass invade.

[Ted Calver]

Alex,
Same thing happened with my lawn. I put down a granular pre-emergent in the spring that worked for a while, but when I started seeing new crab in the lawn I hired one of the national green lawn companies. They wiped it out for most of the summer--when we didn't have a lot of rain. Now, after some nice long soaking rains..it's back. There might be something to the rain theory.

[Ben Grunow]

I believe most of the weed killers used by these companies are liquids that coat the leaves of weeds and kill them (not granular that dissolve slowly). I think they work on weeds that are already growing and the preventer is a one time, spring only type thing so new weeds can grow after time and rain wash it away.

Dont know the answer but thought this might fuel the conversation.

[Alex Berkovsky]

Depends. Early in the season was a long time ago. How short are they cutting the lawn? When is the last time it was aerated and over-seeded? Weeds like crabgrass are "opportunistic" and thrive more when there is plenty of light to help their seeds germinate. A rich, thick lawn is less likely to let crabgrass invade.

I'd say they are cutting the lawn short (too lazy to run out with a ruler ). It wasn't aerated or reseeded. In fact, they are starting to aerate now and offered the service to me for $100.

[Mike Dauphinee]

Alex, you can wet the grass and sprinkle good old fashioned baking soda on the crabgrass and it will kill it. Should leave the good grass alone. (But depends on the variety) Crabgrass is a fast grower and water is its friend.
Also, when mowing try to use a bag as it will help prevent seed spread. Do not use a mulching mower and you can have it thinned out in a few weeks.

HTH

HAND

[Alex Berkovsky]

Alex, you can wet the grass and sprinkle good old fashioned baking soda on the crabgrass and it will kill it.

Mike,
Thanks for the tip; I will give it a try. Yet another use for baking soda.

[Joe Mioux]

Pre-emergent herbicide should go down in the Spring when the soil is cool.

Post-emergent herbicide now.

Crabgrass needs warm temps and water. This is why you normally see crabgrass near sidewalks. The concrete adds heat and water runoff if abundant with rains and people washing cars in the driveways, etc.

A golf course chem saleman once told me to apply Milorganite at Thanksgiving and then mid Dec apply weed and feed. This particular pre-emergent herbicide was listed for 9 months effectiveness on weeds such as crabgrass.

Different pre-emergent herbicides also have different lengths of time for their effectiveness in controlling weeds.

HTH
Joe

[Ted Calver]

Here in VA the lawn companies start peddling aeration in september for cool season fescue lawns like mine. Then it's time to top dress with compost and reseed. If you lay down a pre emergent herbicide to control the late season crab grass you will mess up the reseeding. If you intend to reseed read all herbicide directions carefully.

[Leigh Costello]

Before you get too far, check your neighbors lawns. Their weeds may be giving your lawn a fresh batch of weeds everytime they get their lawns mowed. And if this is the case, stock up on post-emergent weed killer and/or baking soda.

HTH