|I need to know that if Weed Killer and Crab Grass Preventer can both be used at same time. After using them after how long I need to put the grass seed on some patches on my lawn. Lastly if the day temperature touches 60 and night temperature is around 48 degrees can i use Weed Killer and Crab Grass Preventer?
|Answer from NGA
March 14, 2010
|Crabgrass starts germinating when soil temperatures are 50 to 55 degrees F for ten or more days and germination can take place over a 6 week period. Pre-emergence herbicides provide excellent weed control for crabgrass but they last only about 30 days. The compound prevents the weed seed from germinating, but it will not kill any newly sprouted seedlings. You can use a combination product such as Scott?s Turf Builder with Halts which will fertilize, kill weeds and prevent crabgrass. However, if you use this or any other product with a pre emergent you will have to wait from 30-90 days before overseeding your lawn. The product will list the waiting period on the label. Hope this answers all your questions.
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