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Chemical-free Corn Gluten Meal KillsWeeds, Feeds your Turf and Doesn'tThreaten People and Pets!
Q. Dear Mike: PLEASE HELP! Mylawn is in terrible shape. The crabgrass last year was horrible, aswere other weeds. I have used Scotts in the past but nothing last year,when I decided to go completely organic for my cats, who are constantlyeating the grass. What do you recommend?
---Eileen; just outside of Philadelphia
Can you help me take care of my lawn—preferably organically? Mylate husband used to do all this for me; he put something on in March—a"pre-emerge" that helped keep a lot of the dandelions and other weedsfrom sprouting. I still have the drop spreader he used. I didn't doanything last Spring, and I thought the dandelions were going to takeover the front yard, but then the rains brought the Bermuda grass intoits own, and it just grew those dandelions out of a home!
---Earlie in central Oklahoma
My husband and I moved into a new home last year. Despite having usedScott's lawn service since they laid our sod, we have lots of weeds—aswell as bare spots that need reseeding. More importantly, we have 2children and I am 7 months pregnant with our third. I would like to tryCorn Gluten Meal to control the weeds, but I'm afraid it might preventthe grass seed from germinating. Please give us some guidance. Thanks!!
---Susan in Maryland
A. And that's just the tip ofthe lawn care/corn gluten meal iceberg in our email box!
First, the basics. A decade and a half ago, Iowa State Universityturf grass researcher (and frequent YBYG guest) Dr. Nick Christiansaccidentally discovered that corn gluten—the protein-rich componentleft over after they make cornstarch—prevented seeds from germinatingsuccessfully. Now, he already knew that corn gluten would make a greatlawn fertilizer—it's a whopping 10% nitrogen, the food that grasscraves the most. (Ten pounds of corn gluten spread on 1,000 sq feet ofturf supplies a full pound of lawn-lushing nitrogen!)
But this new discovery meant it would also kill Springtime weeds—thuscreating an all-natural replacement for the toxic chemical weed andfeed products that threaten people, pets and the environment. (Someherbicides in chemical weed and feeds have been linked to increasedrates of cancer in people and dogs, and their harsh chemicalfertilizers cause huge problems in environmentally sensitive areas likethe Chesapeake Bay.) Corn gluten received a federal patent as a naturalpre-emergent herbicide in July of '91.
As with chemical pre-emergents, Nick explains that timing iseverything. Right now, the seeds of crabgrass and many other weeds arelying dormant in your lawn, just waiting for warm weather to germinate.But if you spread 10 to 20 pounds of corn gluten meal per thousandsquare feet of lawn when the first yellow blooms appear on forsythiabushes in early Spring, you'll prevent those early season weeds fromsprouting successfully.
Yes, corn gluten does prevent the successful germination of all seeds,so you can't reseed any bare spots or sow a new lawn when you use it.But Spring is NOT the best time to do such things anyway; you have amuch better chance of success in the Fall. If you MUST fix a spot ortwo this Spring, get the gluten down early—when the first Spring bulbsappear. Then you can safely sow grass seed six weeks later, when thegluten will have lost its herbicidal effect. (But I wouldn't bother ifyou have a spreading type of grass, like Zoysia or Kentucky blue; itshould fill in bare spots without any help once you begin taking propercare of your turf.)
Technically, perennial weeds like dandelion, red clover, foxtail andbentgrass shouldn't be affected, because they're already there. Butapparently nobody told the corn gluten. The Iowa State researchersnoticed that these—and other—really tough weeds became scarcer andscarcer in their test plots year after year, until by year three orfour they were gone or reduced to very minor levels. Nick feels thatsome of this is due to the prevention of new weed seeds from sprouting,but attributes the main effect to the fact that corn gluten's naturalslow-release nitrogen helps grass grow the kind of strong roots thatcrowd weeds out. As our Oklahoma listener notes, happy grass beats theworst weeds.
Corn gluten meal comes in powder and granulated forms; granulated worksbest in conventional spreaders. Gardens Alive, which sells both underthe brand name "Wow"(for 'With Out Weeds'), was the first company to license corn glutenfrom Iowa State, and the company that registered it as a naturalpre-emergent herbicide with the EPA.
Retail? Nick Christian's corn gluten page at Iowa State (http://www.gluten.iastate.edu/)lists every company that has a current license to sell the product. Andhere's a great scientific article about CGM that's easy to read andgoes into lots of detail—especially about the weeds it affects: http://www.gluten.iastate.edu/pdf/control.pdf
To get the best results, water it in really well and then allow thearea to dry out. Any weed seeds that try and germinate will be killednaturally by the gluten. Then it will slowly release its lawn feedingnitrogen to build up the kind of healthy turf that naturally resists—orjust plain kills—weeds without any direct herbicidal help.
…as long as you care for your grass properly, that is. Most peopledon't. So we'll reveal the rest of what you need to know to have aweed-free lawn without any chemicals (and with a lot less work thanyou're probably doing now!) next week…
You Bet Your Garden Question of the Week ©2005Mike McGrath
HelpfulProducts From Gardens Alive!
Look below for some of the best Organic products for your Lawn!
Pre-Emergence Weed Control and Fertilizer
WOW! Plus lets you control pesky weeds while feeding your lawn with acomplete, balanced, and all natural
fertilizer. Easy to apply so it saves you time and money!
Guardian™ Seed-Starter Mat
Easy, effective way to ensure fast germination of lawn seed
After you sow your lawn seed (we recommend Turf Alive! III for mostlawns), roll out this neat carpet of 100% weed-free wheat straw, waterit down and relax! The mat keeps seeds in place, shields them frompecking birds and holds moisture better than straw.
TurfAlive! III Brand
Grows slower, stays shorter!
Turf Alive! III Brand grass sprouts and establishes itself fast. Yetonce it has been established it grows more slowly cutting down onmowing. Also has deep root system so it stays greener longer!