The Crabgrass Conundrum
Crabgrass is one of the many pesky “grass like” weeds found throughout the United States. Again, it is particularly bad in the east and southeast. Unlike dandelion, crabgrass is an annual plant, dying each year in the fall. However, before it dies it leaves tens of thousands of seeds to keep the family going next year. The common reaction to a crabgrass problem is to spread what is called a “pre-emergent” herbicide (Team, Betasan, or Dacthal) on the lawn in the spring to prevent the seeds from ever germinating. There is no question that such an herbicide will definitely work if properly applies, but there is a problem with this strategy. Unless you overseed that lawn, previously inhabited by lots of crabgrass plants, the grass is going to stay thin and there will be a need to protect yourself with pre-emergent herbicide every year. But you can’t plant grass seed because the crabgrass killer kills all seeds, including grass seeds. It is a classic Catch 22.
Crabgrass is probably the most common grassy weed found in the lawn. There are other grassy weeds, but the technique for dealing with them is about the same as for dealing with crabgrass described below.
The Crabgrass Strategy
So here is a strategy to rid your lawn of crabgrass and many other similar grassy weeds. In the spring, instead of using crabgrass killer, overseed your lawn to make it more dense. Perennial ryegrass is the best grass for spring planting. Then you raise your lawn mower to 2 or better 2 ½ inches for the whole season. You will still have some crabgrass, but not as much as last year. Then in the fall, overseed the lawn again. Keep that lawn mower high from then on and by the third year you will see very little crabgrass. You can be sure the crabgrass seeds will still be there, but there will be no room and no light available for germination.
Creeping Bentgrass Patches
Question
We have a home on Lake Huron and planted the lawn with seed ,it was a slow start , we fertilized it ourselves, but after about 3 years we hired tru-green and it took off. This year we changed to a local company and now have spots of bright green grass that we are told is like a golf course grass. It seems to be taking over our finally beautiful grass. Is it the chemicals that is a problem in this change or is this new grass seed that gets blown in from somewhere.
Thanks, N
Answer
You are being blessed with Creeping Bentgrass, commonly used on golf courses but not desireable in a home lawn. It is tough stuff to control and may take two seasons. Your timing is just right in terms of season. Spray the spots with RoundUp, a non-selective herbicide that is not going to move into the lake. It kills the plant and the roots. You will kill some good grass, but not much if you are careful and work close to the patches. It takes two weeks for the RoundUp to work. Do that job in the first week of August or thereabout. Then in the last week in August, or Labor Day weekend, rake up all the dead grass, loosen the soil, and plant standard grass seed fairly thickly. You might want to look into buying some material called Grass Fast which is designed to increase germination; available at garden centers. Water, water, water. If next spring some Bentgrass appears, hit it right away with the same treatment.
Jeff
