Lawn care question/pre-emergent crabgrass preventer and overseeding - Ask Extension
Hi there!
I always put down Halts pre-emergent crabgrass preventer and fertilizer every Spring when the forsythia bloom. Then I use Milorganite twice ...
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Lawn care question/pre-emergent crabgrass preventer and overseeding #449261
Asked April 23, 2018, 8:39 PM EDT
Hi there!
I always put down Halts pre-emergent crabgrass preventer and fertilizer every Spring when the forsythia bloom. Then I use Milorganite twice per season and a Winterizer in the late Fall. This year, I'd like to try to get my lawn a little thicker and more robust but I know that I can't do any over-seeding if I use Halts. What do you recommend? Is there a crabgrass preventer that I can use that will still allow grass seed to germinate? Should I overseed and worry about crabgrass and weeds later, hoping to choke them out? If so, what is the best way to overseed?
Also, when is it appropriate to de-thatch as well as aerate?
Any expert advice on how to get my simple suburban lawn looking great this Spring would be appreciated!
Thanks!
Jon Moshier
Oakland County Michigan
Expert Response
There are a lot of questions here, but first the basics and most important. More lawns are failing because of cultural practices (mowing) than for any other reason. Raising the mower height to 3 inches or higher is the single best thing that homeowners can to improve their lawn. The top growth supports the root growth and not the other way around as is commonly thought. Scalp your lawn and it jettisons roots it does not need. Their is simply no other way to have the dense turf desired than mowing higher, no matter how much money is thrown at it.
When you do this the need for pre-emergents becomes less and less as the lawn thickens. This because higher and denser turf shades out weed and crab grass germination/growth and otherwise leaves little room for them to grow.
If you are going to use pre-emergents, understand how they work. They set up a chemical barrier to prevent germination on the lawn surface. What this means is that the lawn should be raked a clean as possible before application. Raking afterward destroys at least some of that barrier, the most common reason for failure. If dethatching, the time to do that is before pre-emergent application. Get your lawn as clean as possible before, and leave it alone after.
I appreciate the desire for lawn improvement in the early spring, but the fall is the best time for improvements when growing conditions are the best for optimal growth. That is the best time to have the core aeration done, which breaks up compaction and allows nutrients to get to the root zone, also the best time for reseeding. Think of the early fall fertilizer, late August/early Sept as no. 1 and most important for the year rather than any spring application. Root growth only happens when soil temps are between 50 and 65 degrees and fertilizing at those times really "makes hay." The winterizer should be considered no. 2, applied about Halloween, as it sets up the lawn for the next growing season, meaning an early spring application is not necessary. No. 3 in importance would be the spring application, about Memorial Day. Do not fertilize through the heat of summer to stimulate growth that is not going to be supported by root growth, a process that can create more thatch. Spot treating the inevitable weed that will get into your lawn with a Weed b Gon product a couple of times per season is effective and some formulations even take out crab grass.
All of this assumes you have a way to get sufficient amounts of water on your lawn as needed. Vital and If not, cutting back on some of the above would be sensible because the truth is that having a nice lawn requires your attention throughout the growing season, as easy as it may sound. Again, the single best practice is mowing high and it costs nothing. Read more here: http://msue.anr.msu.edu/resources/mow_high_for_weed_and_grub_control
Hopefully I've answered all of your questions. Good luck!
When you do this the need for pre-emergents becomes less and less as the lawn thickens. This because higher and denser turf shades out weed and crab grass germination/growth and otherwise leaves little room for them to grow.
If you are going to use pre-emergents, understand how they work. They set up a chemical barrier to prevent germination on the lawn surface. What this means is that the lawn should be raked a clean as possible before application. Raking afterward destroys at least some of that barrier, the most common reason for failure. If dethatching, the time to do that is before pre-emergent application. Get your lawn as clean as possible before, and leave it alone after.
I appreciate the desire for lawn improvement in the early spring, but the fall is the best time for improvements when growing conditions are the best for optimal growth. That is the best time to have the core aeration done, which breaks up compaction and allows nutrients to get to the root zone, also the best time for reseeding. Think of the early fall fertilizer, late August/early Sept as no. 1 and most important for the year rather than any spring application. Root growth only happens when soil temps are between 50 and 65 degrees and fertilizing at those times really "makes hay." The winterizer should be considered no. 2, applied about Halloween, as it sets up the lawn for the next growing season, meaning an early spring application is not necessary. No. 3 in importance would be the spring application, about Memorial Day. Do not fertilize through the heat of summer to stimulate growth that is not going to be supported by root growth, a process that can create more thatch. Spot treating the inevitable weed that will get into your lawn with a Weed b Gon product a couple of times per season is effective and some formulations even take out crab grass.
All of this assumes you have a way to get sufficient amounts of water on your lawn as needed. Vital and If not, cutting back on some of the above would be sensible because the truth is that having a nice lawn requires your attention throughout the growing season, as easy as it may sound. Again, the single best practice is mowing high and it costs nothing. Read more here: http://msue.anr.msu.edu/resources/mow_high_for_weed_and_grub_control
Hopefully I've answered all of your questions. Good luck!
