In general, it tends to work best on common weeds like crabgrass. Corn gluten is also a good source of slow releasing nitrogen fertilizer (9-0-0) for your lawn. Using a fertilizer spreader, apply it at a rate of 20lbs per 1000 sq ft. of turf and scratch it into the topsoil. Follow with a light watering so that it sprouts seeds. Don't worry; these seeds will not develop roots.
The trick is in the timing. You need to time application in the spring prior to the weed seeds developing roots, but avoiding rainfall, so that the corn gluten has time to do its thing before being eaten by microbes. Once the weeds establish roots, the corn gluten loses its effectiveness as an herbicide. However, it will still act as a fertilizer and grow you a healthy crop of weeds. Don't plant seeds where you've applied corn gluten for at least 60 days following application. You can find corn gluten at feed mills or grain elevators.
Here's some weed and feed alternative tips I found...
What should I do instead?
Accept a few weeds. Many people who see a lawn with as much as 10 to 20% weed cover still consider it healthy and good looking. Clover in your lawn actually fertilizes the soil.
Pull or spot spray the ugly weeds and leave the others alone. Long-handled pincer-type weeding tools, available in many garden and hardware stores, make it easy to pip out weeds without stooping.
Use a natural organic or slow-release fertilizer instead of a quick-release fertilizer. For year-round lawn health, it's most important to fertilize in September.
Mow your lawn to about 2" (depending on grass type). And leave the clippings on the lawn to help fertilize naturally.
Water deeply but infrequently (about 1" of water a week in summer, less in spring and fall).
Overseed thin areas of your lawn in the spring and fall to crowd out weeds. Just rake to expose the soil, spread seed, and cover with ¼" of compost or soil.
Consider alternatives to grass for steep slopes, shady areas or near streams and lakes
Small dandelions can be pulled out by getting to the bottom of the leaves and pulling counter clockwise, like unscrewing the weed. If they are large, use a weed tool to loosen the dirt, then pull the dandelion out in a counter clockwise direction. Beats me why it works but it does!
I really don't think there is a happy alternative to this situation. We had a very warm Jan. and postponed putting out the corn gluten meal just because I kept on thinking it was going to get colder. This is Dallas, TX, zone 8A.
Well, it became colder, then warmer.....like a yo yo.
Is this a case of a one time application having poor timing in a no win situation?
We put the corn gluten meal out last week, too late for the weeds that are now flourishing in our dormant lawn as of Jan.
Am wondering if the weather would actually produce successive crops of weeds because of the back and forth cold and warm weather.
Any suggestions or thoughts on the matter?
I am looking for a recipe for a weed killer/lawn fertilizer combination. I think it has vinegar, dish soap, and two other ingredients. The recipe was given to me years ago and I can't find it.
I know a vinegar mix will kill off weeds, but it will also kill the grass. So be very careful of what you spray. For weeds in cracks and crevasses I use 4 cups white vinegar, 1/4 cup salt and 2 teaspoons of dish detergent. Spray plants especially at root level.