There are several organic weed control options now being explored, some more successful than others.
One of the most important breakthroughs in organic lawn care has its roots in a fortunate accident by Iowa State University researcher Nick Christians. The natural herbicide that resulted from his research (made from corn gluten meal) is now patented, and is licensed for use in turf and home gardens as an alternative to weed and feed products.
Corn gluten meal is a by-product of the wet milling process of corn for starch. It is also produced as a by-product during conversion of starch from dry-milled corn to corn syrup.
Corn gluten meal has been found to offer pre-emergent control of dandelions and crabgrass and is also a slow-release organic fertilizer.
Pre-emergent control means that it inhibits the germination and establishment of new seeds. This product will not control existing established weeds, so it needs to be used over a number of years in order to achieve good results. The existing weeds will eventually complete their lifecycle and die, but new weeds will be slow to establish. If you are overseeding a lawn, we recommend not using corn gluten until the new seed is established.
Spring and fall applications are best because this is when the majority of the weed seeds germinate
Corn gluten meal is a powdery byproduct of the corn milling process. Used for years as a supplement in hog feed, this natural protein is very effective for lawns and gardens as a plant food as well as a weed suppressor. Corn gluten meal products offer a non-toxic, yet effective alternative to traditional, chemical-based weed and feed products for weed control in gardens and lawns, paths and driveways.
As a plant food, corn gluten has a N-P-K ratio of 9-1-0, or 10% nitrogen by weight. As a weed suppressant, corn gluten acts as a natural "pre-emergent"— it inhibits seed germination by drying out a seed as soon as it cracks open to sprout. These qualities make corn gluten an ideal 'weed n feed' product.
Vinegar is an acid, and when applied to plant tissue it destroys the leaves. It offers non-selective control of weeds, meaning that it damages all the plants it is applied to, including turfgrass. It is important to remember that vinegar does not kill the roots of established weeds. It only kills of the top growth, and an established weed will recover and grow new leaves. We generally use this product to control weeds that are growing in cracks and crevices of sidewalks and patios. We also use it to spot treat weedy patches in lawn, however we strongly recommend overseeding with some grass seed in these areas or new weed seeds may germinate and get re-established. Vinegar can also be used as a blanket application in a renovation where the existing lawn is full of weeds. The vinegar application would be followed by an slit seeding or overseeding.
Topgun is made using naturally occurring fatty acids (soaps). When applied to a weed, the soap rapidly desiccate the leaves. Like vinegar, Topgun only kills the top growth and not the roots, so regrowth can occur.
Topgun can be used to spot treat patches of weeds in a lawn but we strongly recommend overseeding to establish turfgrass in the treated areas in order to prevent weeds from getting re-established.
Topgun can also be used as a blanket application in a renovation where the existing lawn is full of weeds. The Topgun application would be followed by an slit seeding or overseeding.
Beet extract is a by-product from processing of sugar beets. Beet extracts are not registered as a weed control, but they can play an important role in managing weeds in a lawn. Beet extract stimulate robust growth in the lawn but they can also initially cause spotting or browning on the edges of the weeds and turf. The turf rapidly recovers from this spotting, but studies have shown that several weeds recover slowly. We cannot make claims of weed control with this product because the product is not registered as a weed control with the government. The beet extracts are currently being used as organic based fertilizer, and when used in combination with aeration, overseeding, topdressing and proper mowing and watering, is an excellent way to naturally manage your lawn weeds. We also use the beet extract as a spot treatment to weedy patches within a lawn, to stimulate robust turf growth in those areas.