Gardenbite: Containing the Uncontainable: Managing Bamboo | #GoodGrowing

Welcome to the Good Growing podcast. I am Chris Enroth, horticulture educator with the University of Illinois Extension coming at you from Macomb, Illinois, and we have got a Gardenbite for you today. Maybe you've planted it, or perhaps it was the last homeowner who made the fateful decision. Either way, today, maybe you have to deal with it. Now we could be talking about a lot of different plants here, but but for this particular episode, we're going to look at bamboo, particularly running bamboo.

Yes. The very plant that has plagued many homeowners over the decades and centuries. They've even led the lawsuits and, bitter, arguments between neighbors. You might be thinking, wait. This is a University of Illinois Extension podcast.

Bamboo doesn't grow in Illinois, does it? It's such a tropical looking plant. Well, news flash, and something that I didn't realize until, you know, I was well into my horticultural learning is that, yeah, bamboo, at least certain species, do grow here in Illinois. Now bamboo is a term that we use to describe over 1,000 species. A lot of those are also available for purchase in the landscape trade.

And while not all are hardy enough to grow here in Illinois, there are definitely some that will. There are certain types of bamboos with names like bisset bamboo, nude sheath bamboo, the yellow groove bamboo, red margin bamboo, and the list goes on and on. Now generally speaking, you're gonna find everything that's sold in Illinois cold hardy at least to Zone 4. That's kind of where I've seen the the extent of most of the cold cold hardiness of these different ones that I've just named. Now all of those are a non native species of bamboo, but did you know Illinois also has its own native species of bamboo?

Arundinaria gigantea, also known as giant cane or river cane. Now this particular species is hardy to Zone 5 and was commonly found in Southern Illinois at the time of European settlement. In fact, there's a lot of accounts of several of the lowland areas or bottomland areas just being filled with this river cane or this type of bamboo. And the the interesting thing, about it is that it's it's very rare in regards to its development now, and you're might be thinking, well, how if bamboo is such an aggressive plant? Well, when it comes to the cases, maybe more specifically as this this river cane or this this giant cane, they grow in colonies.

And so the rhizomes grow underground, these colonies grow underground, these large colonies, now they're all genetically clones. All of the the the leaves that rise up, flowers vary occasionally, but when it does, it needs to have something with enough genetic variability to then pollinate those flowers. And when you're a really large colony, that can be tough to do if you don't have many left. And so a lot of those historic ranges of giant cane down in Southern Illinois have been flipped into agricultural production or just been developed into, like, residential or commercial spaces. Because in Southern Illinois, if it's not forest with that kind of clay forest soil, then it's that lowland area, pretty decent soil comparatively to that forest soil.

So a lot lot of it has been developed. So it it is really a sight to see when you run into our native bamboo down in Southern Illinois. Now it is hardy to zone five. So I think there are some people that have been trying to grow it up here in Central Illinois as well and have been successful. I mean, it readily roots, will readily keep growing.

And I think there is an effort actually down in Southern Illinois, Carbondale, to maybe create some kind of a reservoir of genetics, maybe help keep this plant going a little bit longer. Also, looking at, you know, introducing it more into the landscape trade. Now I remember as a student down in Carbondale, I toured an arboretum, and we came upon a circular just grove of bamboo. And I I just remember thinking, that's beautiful. I loved it.

It just looks so just I just look great. I I there's there's my words to describe it would be just the texture was different. The the forms were different. I just love seeing it. Now I didn't know at that time of my student life to ask a question of whether it was the native giant cane or the non native running bamboo, but I have a sense maybe it was a native giant cane, but I really don't know.

I wish I did. But either way, I liked them. I liked the way it looked. And I also do kinda like the way running bamboo looks. Oh, and a fun fact that the our native bamboo is actually the largest grass that grows in Illinois.

So if we go back and we sort of look again at bamboo as this larger grouping of plants, we can divide it into two basic growth habits. We have our running bamboo, which we will cover, but then we also have clumping bamboo. And there is a definite difference between this, if you can tell by the way they've been named. Now, clumping bamboo is a pachymorph. This this describes the character of the spread of its rhizomes, rhizomes being these underground stems.

So pachymorph, it it is a very slow spreading rhizome or as opposed to the running bamboo that is called a leptomorph, like leaping. It's in in my mind at least. So I I really like the way that they name these. I think, you know, finally, something makes sense in terms of how, maybe a scientist has named them. So pachymorph is that clumping bamboo.

They pack them in. It's a really tight, cluster of rhizomes. And where the rhizome, that underground stem where it goes up, it creates this above ground stem called a comb. It's that upright stem, and then on that we have our our bamboo leaves and things, but that's what we see above ground as the comb. So for those pachymorphs, those rhizomes, they they immediately as they, bud off of that main mother rhizome, they just immediately turn upward into a comb, and, so that's why they slow they they spread very slowly.

Whereas with the running bamboo, they have larger spaces between where the combs will emerge vertically out of the soil. And so that that's where the the the main differences in that growth habit comes from. And and so as you can probably assume, the clumping bamboos are not typically considered, like, an aggressive species. But I will say, based upon what I've read, just because they're not aggressively spreading does not mean that they're not difficult to remove. I've heard stories where it can be kind of like trying to get rid of yucca out of a yard and which is a very difficult plant to get rid of.

Now if we look at that leptomorph growth habit of our running bamboo, a lot of people will ask, well, how far can a running bamboo run? And according to the University of Maryland, indefinitely, unless that growing tip is damaged. Now I don't know necessarily how what other studies might have been done to show is this really, like, can go on forever. One other source I did say see that they said that it's about a 100 feet that they have measured, that underground rhizome of running bamboo going. So that's a long way.

I've heard of stories of of running bamboo coming up on the other side of a home, whether it's planted on one end and it winds up on the other. So they they can, to their namesake, run. But you might be asking, well, if clumping bamboo is not as aggressive, why don't we see more of that being sold in the landscape trade? And, well, you can actually buy clumping bamboo. However, there is a shortcoming, if not multiple ones.

So one of those is that this group of bamboo, clumping bamboo, is very sensitive to our climate. Now there's many species within here, and so some species, they they don't like our heat or our drying winds that we have in the summertime. There are other species that just really can't tolerate our cold winters. And so it's kinda difficult to find the right species that would grow in Illinois. Probably the the genus that would work best is the Phargesia or Phargesa, And this called mountain bamboo.

It's probably considered the most cold hardy and is grown up in Zone 5, so that's Central Illinois. But as we've said, it is a very slow grower, and it will reach its mature size over the course of about twenty years. And I don't know about you, but I know when people talk to me about bamboo, they're not talking about slow growing. They want something fast. And so that's what they think about when it comes to bamboo, fast growth.

And so that's why a lot of people are going to turn to running bamboo. It's the speed of the growth. Somebody want might want a a quick privacy screen. Well, running bamboo will fit that bill. The combs of the running bamboo, they emerge in the springtime, and they are going to reach their full height, which will range between 10 to 30 feet, kinda depends on the species of running bamboo, but it's going to reach its maximum height within that year.

And so boom. Have an instant, pretty much privacy heads or screen that you would want. Plus the combs, though a lot of times I see them described as evergreen, they're not technically evergreen, They they do persist throughout the wintertime, but the combs or the the leaves on the plants, they they are shed every year, but they're replaced also every year. So it just has sort of that year round kind of presence within the landscape. Plus, did I say that just bamboo looks cool?

Alright. So if you are tuning in here and you're thinking, well, I think, Chris, you're kind of convincing me to plant bamboo. Well, I would say do so with an abundance of caution. And so let's talk about containing bamboo. Can it be contained?

Well or or the another situation, maybe you have a patch of bamboo already, and you want to eliminate most of it, but you wanna keep some of it. How do you keep it in its spot? How do you keep it where where you want it? And that's when we turn to rhizome barriers, and this is gonna involve a little bit of construction. So the function of a rhizome barrier is to block the bamboo rhizome from growing out of the contained area.

Essentially, what it does is it it hits this barrier and it forces this growth upward where you can see it. And if you can see it, that means you can then manage it. Now to work, the entire colony of bamboo has to be encircled by this barrier. Now a single properly installed barrier is recommended. However, kind of doing a little bit of reading before recording today, I saw some bamboo enthusiast.

They would actually put in a second barrier, like, two feet away from that initial barrier. Kinda, I guess, just maybe as a little bit of extra insurance to keep the bamboo colony in check-in in that spot. Now where would you buy a rhizome barrier? Basically, lots of companies sell it. You could probably go to a local garden center and ask around, or of course, look online.

You'll find a lot of different ones there. But when you're shopping, here's a few things that you want to look for. So first off is the how deep do you need to go? And so we're gonna be looking at a rhizome barrier that is probably at least 36 inches wide, which we're gonna turn on its side, and that's gonna be the depth of the rhizome barrier. So 36 inches wide, and the length should be enough to be able to encircle the perimeter of that bamboo colony.

What is this made of? Well, it's gonna be a very heavy plastic. The minimum thickness is gonna be around 60 mils. You probably wanna go up to 80 mils for this. The plastic, is gonna be not just your, like, basic drop cloth.

You're gonna wanna have something that is made for this, that is treated to resist UV degradation because it's gonna be exposed to sunlight. You'll hear about that in a second. But the plastic, you're gonna want some type of polypropylene. On the label, it's probably gonna be abbreviated to PP or a high density polyethylene. That's gonna be abbreviated to HDPE.

So those are the kind of the the materials that you're gonna be looking for. And you really stress this is that you don't wanna have to make many cuts when you're installing this. Ideally, this is gonna be one continuous piece with the two ends, you know, seamed together. However, the manufacturer recommends it in their instructions, but you you really don't wanna have too many cuts or or seams where where possible. The other thing I did notice too is that some folks would talk about open air trenches.

So they would literally dig, like, a three foot deep trench around their bamboo colony. And, you know, rhizomes, once they are exposed to that air, they I mean, they're not gonna grow any further. I've even seen people do moats, like a water moat around, their bamboo colony. Again, similar situation. The the rhizome's not gonna grow through the water.

Now there are issues with this, though, because if it's a moat, well, moats can dry up. Moats can, fail. The other thing is if you just have a trench, those trenches will will fill in over time. That's just the way, you know, gravity works, and soil erosion works. So those trenches will fill in over time.

Same with the moat. So, it all requires a lot of extra maintenance, that probably, that most people aren't interested in doing. So let's talk about oh, and also when it comes to a lot of times, people might say, well, can't I just pour, like, a foundation of concrete around my colony? Concrete's not a great choice either because with time, it cracks. And and, actually, a well designed, strip of concrete is designed to crack.

It's supposed to crack. And and and usually where we, create those little expansion joints, you know, that that's where we want it to crack. So that is a spot where a bamboo rhizome might be able to take advantage of the situation. Alright. So let's talk about putting in this rhizome barrier.

It's going to require a deep trench. And if you have a large bamboo colony or space that's going to become that colony, you probably gonna want to leave the shovel in the shed and maybe call someone with a little bit of heavy digging equipment. Because we're gonna wanna be installing or or digging this trench pretty deep, but it's and it's gonna the trench is gonna need to be deep enough to allow for most of that rhizome barrier to be underground, but we're also gonna have about six to eight inches above ground. Yeah. So we're not only are we stopping them below ground, we're stopping them from kind of kinda creeping over top of them too with this six or eight inches above ground.

I'd say, you know, read those rhizome barrier instructions. I did read a few of them would recommend angling that barrier that's above ground, not straight up and down, and not even flared out, but actually angled towards the colony. And I I'm not sure if if there's some kind of growth habit of the rhizome that that helps you just to see that that rhizome trying to creep up and over if it's angled towards the colony or not, but I did I noticed that recommendation in a couple spots. So you've dug your trench. You've installed your barrier with that little six inch or six to eight inch lip above ground.

Now you're gonna backfill. And when you backfill, you want to tamp that soil down to really compact it around that barrier because that compacted soil is itself also another barrier to the rhizomes. And so as those rhizomes hit that compacted soil, it's gonna force them to grow upward. And then if they've hit that rhizome barrier and they're growing up, you're gonna see them emerging from the soil, hopefully, within time where you can just cut them or, remove them, without them sneaking over top or, or trying to get around some other way. The other thing I noticed is that a lot of folks will will recommend you wanna keep all mulch, all leaves, debris, any of that away from the rhizome barrier.

Again, we're using this buffer space around this rhizome barrier of, like, six inches to a foot on either side to monitor for bamboo for bamboo growth because that's gonna be our kinda our management, space right there. So make sure that you're you're you're have that debris away there, and you're watching this. You're checking on this at least annually. So remember, those running bamboo combs do emerge in the springtime. So you definitely wanna check-in the spring to see how far it's grown within that year span.

So now we've talked about what is bamboo. If we wanna keep some bamboo or gonna plant some bamboo, how do we contain it? Now how do we control bamboo? How do we manage it? How do we get rid of it?

And I will say there are options, but there are no silver bullets in this, in this regard. So, let's let's start with nonchemical ways. The first one is going to be a routine cutting or mowing of the the combs, all the above ground growth. And and you can do this over and over again for years and years, and this will eventually exhaust the root system. However, this does take a long time.

I said years and years. Yes. Because bamboo stores a lot of energy underground. The other thing is you have to be sure, especially if this is in, like, a a boundary spot between multiple properties that you are contain that you're mowing the entire colony because if there's a portion of that colony in the on the neighbor's side or or maybe hiding somewhere in, like, a shrub bed or somewhere else, that growth will continue to feed that main colony that it's it's it's emerged from. So you wanna be treating the entire colony if we're mowing it.

If if mowing isn't an option, if you want a more quick, decisive way without, again, the use of chemicals, it's gonna have to resort resort to just digging it out. So we're, again, gonna be calling someone up with some heavy digging equipment, and they are going to use, that equipment to dig out the entire bamboo root system. It's fast, but it's very destructive. I I would say, again, we are not necessarily going to be using a shovel for this. This is, bamboo has a a pretty expansive root system.

I mean, most of it's in the top 12 inches of soil, but it's just it's just tough. Any little piece that's left behind is going to resprout. And so we wanna make sure to get all of the rhizomes out as possible. Now if even if we're using earth digging equipment, yes, you're probably gonna miss a rhizome or two. You're gonna get re sprouts.

You're gonna have to monitor that. And so so just digging it out, it might get rid of most of the problem, like 99% of the problem, but you gotta keep coming back and monitoring for that extra 1%. There's a little bit of rhizome that might have gotten left behind. And and just if we're going chemical free, we're we're just kinda cutting off any residual, combs that we see popping out of the ground after digging. The other thing about digging is now you have to replace the entire, soil that you've taken out, and you have to find a spot to dispose of the bamboo.

Not every place in, I would say, Illinois, United States, wherever, will accept soil full of bamboo rhizomes. So you gotta check on that. Alright. So we have talked about the nonchemical options, which is basically cutting constantly, digging it out, and then cutting in any of the residuals. Now a lot of homeowners that are gonna turn to herbicides, and we're we're really kinda we need to use both mechanical and chemical choices probably for the most effective use of our money, time, to try to get the space back into something maybe other than bamboo.

So, herbicides are are they gonna be another tool in our tool belt? Really, we're gonna be looking for nonselective systemic herbicides, and probably the best example of this is gonna be glyphosate. It's probably the one of the most surest things that you can spray without any long lasting residuals compared to some of the other active ingredients that are out there. Now I've also seen the active ingredient imazapyr recommended, and this plays into this residual thing I just mentioned. But the the soil residual for imazapyr can has I've seen the remarks in multiple references here, can damage other nearby plants.

And so, you know, since we're working in a home landscape, we're gonna have other shrubs, trees, perennials probably nearby, and imazapyr can damage them. Even some of these references I've read have talked about imazapyr killing fully grown healthy shade trees. And so if that once that bamboo rhizome, once that root system decomposes and degrades, imazapyr remains. And if a tree root comes growing through there, they'll get exposed to that chemical. They'll take it up.

So, you know, that's often why I see most of these, references suggest using glyphosate just because there's just minimal soil residual activity compared to something like a nazepir. Another thing to keep in mind, bamboo is a grass, so some of our other chemical formulations like dicamba two four d are not going to be as successful. Piclorum is another one. Piclorum, the Activin Green, is something I just normally tell people to stay away from in general. But in talking with others who have had running bamboo problems, they have tackled it with piclorum.

The common brand name is Tordon. And they've had poor success, a little bit of control, but but but poor, and then difficulty growing anything any other broad leaves in those spots, and that's because piclorum is also very persistent in the soil. So something to be mindful of. That's why we're we're going with glyphosate here. So when it comes to treating, if you're going to spray your bamboo, you still need to cut it because a lot of that bamboo is gonna be 10 foot tall, 20 foot, 30 foot tall.

We don't wanna be spraying over our heads. We wanna chop it all down, and we wanna treat the regrowth. Now you can you can do that foliar spray, of course, but when you chop it down, you can also do a cut stump treatment on your bamboo using glyphosate. So that's gonna be a bit higher concentrations, for for glyphosate, for that cut stump. But, also, if you're gonna do that foliar treatment, you're gonna wanna do a lower concentration, but typically higher than than maybe what that label might suggest.

Now I always say follow that label. The label is the law. There are some, references online that suggest you want glyphosate solutions or concentrations of 5%, are gonna be something you wanna mix too. But, again, check your label, and read that and follow that to the letter. The key thing to be mindful of if you do the cut stump method is make sure that you paint the herbicide within five minutes of of making that cut just because that bamboo can quickly seal off that wound, and then doesn't matter how much you paint on there, it won't it won't absorb it.

So I hopefully, we we we covered a lot of ground here today, everything from, you know, what is bamboo, talked about our native bamboo, which I am excited to maybe go down to Southern Illinois and and and find see some of those. Also, if you want to grow bamboo, how do we contain it? And then finally, getting rid of bamboo. And as you've probably noticed, there's no sprints here when it comes to managing or growing it. When it comes to running bamboo, it is a marathon.

The same traits that make it a a great landscape plant, the fact that it grows quickly, it's super tough, it spreads easily, those are the same things that makes it difficult to control. So but it's not impossible. You give it enough time, diligence, you can control probably one of the most tenacious plants that can still be sold and planted here in Illinois landscapes. Well, that was a lot of great information about running bamboo and other bamboos in general. The Good Growing podcast is a production of University of Illinois Extension, edited this week by me, Chris Enroth.

Listeners, thank you so much for doing what you do best, that is listening or if you watched us on YouTube, watching. And as always, keep on growing. University of Illinois Extension.