If you had a bad problem with crabgrass last year you might consider treating this spring. Its important to realize that the regular crabgrass treatments prevent any grass seed from sprouting, so do not use them if you are also over-seeding or re-seeding. You need to spend a little more to get the crabgrass control specifically labeled for new seedings. The package will say something about new seeding and the active ingredient will be tupersan. Use the crabgrass treatment to get ahead of a bad crabgrass problem if you must, then get on a regular fall feeding schedule to thicken up your lawn. This will prevent crabgrass in the future so you wont have to keep treating your lawn.
Corn gluten is a natural by-product of making corn syrup, part of the corn kernel, so its safe for humans and animals. It is a good source of nitrogen fertilizer with an analysis of 10-0-0 so if youre interested in an organic program for your lawn, this would be a good choice. Poultry meal products have more phosphorus and potassium than your lawn needs so they are actually not as environmentally friendly of a product for lawns.
Corn gluten also inhibits seed germination to a degree, so it is often sold as an organic crabgrass control. Cornell experts are uncertain to what degree it actually kills crabgrass, they suspect it works by thickening up the lawn with its nitrogen content which then crowds out any crabgrass seeds.
Either way, lawns that are treated each May with corn gluten have less crabgrass than lawns that were not treated with anything. The main drawback to corn gluten is that its more expensive than conventional fertilizer.
Because corn gluten is organic, it needs warm temperatures to be released so apply it once each year in mid to late May at 10 pounds per 1000 square feet. You can repeat this application in late August. No other fertilizer or crabgrass treatments are necessary.
(Amy Ivy is Executive Director with Cornell Cooperative Extension in Clinton County) Office phone numbers: Clinton County 561-7450, Essex County 962-4810, Franklin County 483-7403. Visit our local Web site at http://ecgardening.cce.cornell.edu or email your question to askMG@cornell.edu