Is now the time for corn gluten?
I see that the forsythia are blooming but it seems to be colder than usual so I can't imagine the soil is yet at 55 degrees if outside temperature is not. When would you say ideal date will be this year for Silver Spring - in 2018. Thanking you in advance for your guidance.
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
During and shortly after, forsythia bloom is a rough, but not consistently reliable, guide for application timing. You will have to look at soils temperatures too. If you do not have a soil thermometer, you may have to rely on the forsythia bloom in your area. There are numerous products on the market.
See more on the following publication http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/non_HGIC_F...