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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 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 supressor. 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.
How corn gluten works
Corn gluten meal works by inhibiting root formation in weeds at the time of germination. It doesn’t inhibit roots of mature plants or transplants unless it is used at a very high rate of 80 pounds/1000 sq. ft. or more. Weeds germinate and form a shoot, but no root, which prevents growth. A short drying period is required after germination, because too much water may allow the weed plants to recover and form roots.
Corn gluten does not kill already existing weeds. Existing weeds can be pulled manually or spot treated with a produt such as BurnOut
Corn gluten meal for lawn and garden use comes in three forms:
unprocessed – very fine, almost powdery in texture. Can be broadcast by hand, but for best results use a hand seeder. It will look like a layer of pollen on the soil. Must be applied directly on bare earth or around new plantings because it can’t work its way down through grass or mulch.
granulated – easiest to apply using a spreader. Can also be mixed with water into a paste to use as a patch for localized weed supression. The patch will keep weeds from sprouting while the surrounding plants fill in.
pelletized – can be broadcast by hand. This is an excellent treatment for lawns in spring and fall; a general application will add nutrients to your lawn while discouraging the growth of new weeds. Can also be applied on windy days.
Among the weeds controlled with pre-emergent application of corn gluten are common broadleaf weeds such as:
Dandelions, Barnyardgrass, Curly Dock, Green Foxtail, Black Nightshade, Orchardgrass, Shattercane, Purslane, Wooly Cupgrass, Giant Foxtail, Lamb’s Quarters, Buckhorn Plantain, Quackgrass, Velvetleaf, Annual Bluegrass, Creeping Bentgrass, Black Medic, Redroot Pigweed, Catchweed Bedstraw, Clover.
The three forms of corn gluten meal described above are comparable in effectiveness.
Cost: prices will vary by brand and quantity, but corn gluten-based products are a little more expensive than traditional chemical-based weed n feed products.
Tips for using Corn Gluten Meal
- Coverage depends on which form of corn gluten you’re using, so read the package for accurate application. In general, however, corn gluten is applied at 20 – 40 lbs per 1500sq ft. For best results, it should be twice a year in spring and fall.
- Corn gluten will not work until wetted, so wet it down using a fine soft spray after applying.
- One application effectively supresses weeds for 4 – 6 weeks. Timing is essential in the use of corn gluten meal. It must be applied before the targeted weed emerges above the soil. Since a drying period is required after application, you should make sure no rain is forecast for a few days after application. Heavy soils, protracted rainy weather may reduce its effectiveness.
- Corn gluten is effective for preventing weeds in lawns, but it may also be used for weed control in garden beds and pathways. When used in garden beds, it is recommended that you use transplants or mature plants, or do not apply the meal until the plants are well established.
- Effects are cumulative. Results improve with repeated use over time.
Where to buy Corn Gluten Meal
Surprisingly, corn gluten products can be hard to find. Many garden centers will tell you they’ve never heard of it, while others have products on their shelves which are corn gluten based but use a product name, like “Safe n’ Simple” for example. Look in the “weed n’ feed” section.
You can also shop online for corn gluten meal. The Corn Gluten Fertilizer available at Eartheasy is the only OMRI-certified organic and non-GMO corn gluten available on the market. More info, or to purchase.
More information about corn gluten meal: http://www.gluten.iastate.edu/
