This Johnson grass it’s identifiable by pretty, stocky leaves. It’s in the genus sorghum so it’s actually related to sorghum. It also can be identified by these stupid things: the rhizomes. Johnson grass is magical because it is what has one of those amazing attributes that can reproduce through seed or through rhizome.
If you really want to knock back Johnson grass right now, when it’s flowering and this is mid-september in Kentucky, it may flower a little earlier in other areas or a little later. It’s a really good time to go after it. Basically it’s putting a ton of energy into creating that flower so it’s a really good time to start pulling it out or cutting it back or we’re really going after.
Here is a video about Identifying Johnson grass
My first tip is never let it go to seed. This is one of those crops that I have is like a rule on my farm. It’s a stop what you’re doing and pull it crop. If you see Johnson grass or spiny amaranth going, the seed pull it stop what you’re doing and pull it out as best you can.
Even if that stock rips out, that’s okay, these are what’s called perinatal rhizomes which means they’re basically gonna live through the winter. They’re gonna survive the winter and then reproduce in the spring. But by weakening them, you actually lessen their production in the spring, so ripping that after they put all that energy into flowering. Ripping that stock out in trying to get digging up that rhizome if you can is a good way to really weaken the plant.
My second tip may seem a little bit less conventional. One of the things that I really recommend is if you have a patch of johnson grass that is exactly where you should put your most intensive garden. What I mean by that is where I have the fewest weeds is where I am the most. So all this space I have almost nothing all over on my Brussels sprouts and all that stuff over there almost nothing.
The reason is because I’m always in these places. I’m always working on this so rarely do I ever have big tissues in these areas. Because I’m constantly flipping those beds over and I’m really tending that well it’s if you have Johnson grass in a long season area, that’s when you really risk having an out having it spread and having it become a problem.
Honestly, one of the best ways to get rid of it is put it in a place where you’re gonna be planting a lot of stuff over and over. If you find Johnson grass in a place that is gonna be a long season crop, think about planting something that’s a little bit faster, more intensive baby greens kales, anything that you’re gonna have to cultivate frequently or relative with frequency. It’s when you get into crops that stay there for several months.
So that’s when you run into trouble with Johnson grass and maybe that’s a little bit counterintuitive. But the idea is that you’re gonna be constantly cultivating that area, you’re gonna pull that weed out as soon as you see it, you’re gonna be on top of it so in my mind it’s better to have it that they’re where I always am and where I have the highest production crops versus my long season plots.
Only because if it’s in a long season plot, it’s just not getting as much attention so it’s going to proliferate one third. Just get down on your hands and knees and yank this stuff because if you till it, all you’re gonna do is break up that rhizome and you’re gonna send that stuff spreading all through your garden. I’ve seen what that looks like. I’ve done it myself.
It’s not pretty so if you break this and then you plant these two things, they will grow separately that will grow into Johnson grass definitely. Don’t want to tell it because then you’re breaking it up, spreading it out and planting more Johnson grass.
Now tarping can be effective. This stuff here can be effective at wearing it out a little bit. In my experience, it won’t get rid of the Johnson grass but it will certainly knock it back like I said, weaken it, which is part of the goal. If you can weaken it enough you can start pulling it out and kind of keep it from getting out of hand. There’s no one magic bullet for Johnson grass right ultimately. What you have to do is create a strategy.
I’ve heard solarization actually works a little better. Putting a sheet of plastic down and solarizing them through the summer that can be an effective way to break the Johnson grass. Root down the rhizome and also perhaps get rid of it cover crops I guess can be effective in outrunning the Johnson grass.
Keeping it from being able to photosynthesize and thus keeping the roots from being able to expand, that’s limited in that you can’t till those cover crops in obviously. Because then you’re just gonna spread the root but also if you have it in a cover crop and it makes its way through, then goes to seed and you don’t notice it, that can be a real problem. But I will say that mowing is not a bad idea if you keep it mowed really heavily that will definitely knock back the energy of the rhizome. It was kind of intended as fodder because it does make a good grace for animals.
You’ll rarely see Johnson grass in continually grazed asters and the reason is that those cattle really love Johnson grass and it really wears down the energy level. So eventually after they’ve grazed it, it won’t come back anymore. That’s not really an option for the market gardener.
You can’t really just go out and be trimming it every day. However you can knock back the energy and then be able to get rid of it maybe a little bit more easily. I mean honestly if you have a small patch of it and you’ve identified where that is, I just recommend pulling it the most effective thing you’re ever gonna do to Johnson grass is get those rhizomes out. So get a beer, get friends go out with a trowel and just dig up every single rhizome and do that until it’s gone.
You know you may have to do that every year for a while, because you’ll probably miss a root here and that’s fine like I said, it’s more of a strategy to overcome Johnson grass than it is like one remedy. I didn’t mention any herbicides because we don’t use herbicides. We have no plans to use herbicides.
Acetic acid may work to an extent with which is a certified organic. But we’re not gonna use those things if we don’t have to and we don’t have to with Johnson grass. I feel like it’s way more effective to get that rhizome out of there than it is to try and just kill the plan.
Imaging Johnson grass in a no-till system is a little easier in that there is a little bit more monitoring of the soil. But then there’s also that you’re just not breaking up those roots all the time. However, the Johnson grass is still sneaking through that soil just the same so it’s still an issue in a no-till garden or anywhere.