Remember when the gorgeous yellow blooms are on the forsythia shrubs that it’s time to apply corn gluten fertilizer to your lawn, if you want to arrest the germination of crab grass seed. You can even put corn gluten fertilizer in your garden beds to stave off germinating weed seeds. Remember, however, corn gluten should not be applied where you do want seed germination e.g. lawns, veggie gardens or beds of newly seeded flowers. You must wait six weeks before seeding.