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  • Matt Keenan

Crabgrass pre-emergent

Updated: Feb 26


Is corn gluten meal really the silver bullet in natural weed control? Does it really prevent crabgrass? In short, maybe but realistically? No. In controlled experiments, when corn gluten is put to the test, it is true that you can see a 95% reduction in crabgrass, and you can see for yourself here. But it's going to cost you, to see that 95% reduction you'll need to apply a whopping 46kg per 1000 square feet, that's just over 100lbs.


But I hate crabgrass


Okay, let's say that you are determined, and willing to lug around 100lbs of corn to spite that nasty crabgrass, let's talk price. The best price I've found is from farm feed stores and you're looking at paying about one dollar per pound of gluten, well that means you're paying 100$ on just the product so you'd better hope that you don't own more than 1000 square feet of lawn...


The Kicker


If you're savvy and you're willing to drive your pavement loving hatchback off the beat n' trak to your local farm feed depot, and I'm talking potholes galore to really get that rock bottom 1$/lb pricing because crabgrass isn't going to get the best of you, you'd better hope that what you buy is 10% nitrogen, anything less and you'll need to buy more... And I don't mean 10% protein, I mean 10% N because we're following that aforementioned study to a T. But I've don't the legwork for you and you'll want corn gluten with at least 60% protein, plain and simple. For those of you that are buying bags with analysis, you're looking for an NPK of 10-0-0, the P & K can be whatever, but the N has to be 10 otherwise, you'll need to buy more.



Worth it. Right?


So you shelled out 100 big ones, and I mean just for the raw materials, meaning that if you're paying a lawn care professional 100 bucks you can ascertain that you're not coming close to the sought-after 95% reduction (sorry). But otherwise, you're ready to apply this stuff, let's talk timing.


Can't I just spread it & forget it?


You've come this far and invested time, money, and a new set of shocks because those backroads are unforgiving this time of year, you're not about to just put gluten down without the right timing. And timing is everything, –the best-kept secret in lawn care after all. You'll want to apply the gluten one week before the germination of crabgrass. Knowing when crabgrass germinates is kind of like throwing a dart at a calendar blindfolded, your only advantage is getting to pick the month. But let's say that you have farmer's intuition, your cousin's friend's mother-in-law owned shares in corn crops, after all, so you spread your gluten evenly for the best coverage, success! Right?


Watering it in


One last thing, for lack of a better word, you'll want to "activate" your gluten by watering it in, but just once. The common misconception is that gluten prevents seed germination but this is actually false, seeds will germinate just fine. What's actually happening is not perfectly understood but the current hypothesis is that a protein in corn gluten prevents the newly emerged "radicle" (first part of a seedling) from establishing roots. What this means is, you'll want to water it in to spread the protein around but stop there to avoid diluting it.


"April showers bring May" —crabgrass?


Although you won't see the crabgrass until June or July, April is when it germinates, like many summer annual weeds. I'm writing this in the midst of a two-week-long rain with a couple of intermittent sunny days. How will that affect the gluten you may ask? Initially, the rain will help to water the gluten in but you'll need to cross your fingers, wear your lucky underwear and keep positive because that pricey investment you had just made, may going the way of the Itsy Bitsy Spider.



Silver lining


It may sound corny, but there is a silver lining in everything, including your Saturday spent applying corn, and I'm not talking about getting your steps in for the day either. That gluten you had just put down is not so realistic as a pre-emergent, I hope I made that clear but it's an excellent choice as lawn a fertilizer. With plenty of nitrogen, a touch of potassium, and lots of organic matter, you are on your way to healthier soil.


Wrapping up


I admire anyone willing to go to great lengths to both test and complete a project, I can certainly relate, but in this case, I can save you time and money. The only true way to stop crabgrass and every other weed out there is by out-competing with strong healthy turf. I always recommend doing so with organic fertilizers and soil amendments if you'd really like to see a beautiful lawn year after year with no surprises.


Thanks for reading, I love writing about lawns and I love to see a healthy lawn, I like to think of myself as an environmentalist, you don't need synthetic fertilizers and harsh chemical weed control to maintain a beautiful lawn.


Until next time, take care of your soil, and please share.


Matt Keenan

Renew-a-lawn



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