corn gluten - when to apply?
Hi, I wonder when to apply corn gluten as a pre emergent for crabgrass. I live in Bethesda; is there a way to know what the soil temperature is so I can decide when to apply?
Montgomery County Maryland
Corn gluten has been sold for many years as a preemergent herbicide. It can suppress annual weeds but not as effectively as traditional herbicides.
Corn gluten is a source of nitrogen. Applying it at the recommended amount to control weeds may exceed the amount of nitrogen allowable in Maryland per the Fertilizer Use Act of 2011. Check the label to make sure. Some products are labeled as both an herbicide and a fertilizer.
We recommend fertilizing in the fall, not the spring. Excessive nitrogen applications in spring and summer increases disease problems and reduces stress tolerance.
We do not know what weeds you are trying to control. If you are referring to a crabgrass preemergent look for a preemergent that contains no fertilizer. See our website for timing and Tips for Application http://extension.umd.edu/hgic/crabgrass
Thank you for your reply.
Yes, as my original question stated I wanted to apply corn gluten as a preemergent for crabgrass. I do not use herbicides in my lawn/garden. Can you recommend an organic one? I try to eliminate weeds manually but I thought I would try to prevent the crabgrass from getting a start. I also asked if there is a website that reports the soil temperature for my area or at least the county? It is my understanding that the timing of the application of corn gluten is determined by soil temperature. I am not using a corn gluten product that exceeds the allowed amount of nitrogen.
As stated above, corn gluten can suppress weeds but is not effective as traditional herbicides. Take a look at our page on control options and organic and less toxic controls. In general, going organic means tolerating some weeds. http://extension.umd.edu/hgic/lawns/control-options
There may be websites on line that list soil temperatures but we do not have one to recommend. A soil thermometer is the best gauge. If you do not have a thermometer, (during and shortly after, forsythia bloom is a rough, but not consistently reliable, guide for application timing.