Choosing and controlling bamboo in your garden
Bamboo is one of the more infamous of the invading species people sometimes ‘innocently’ introduce to their gardens and then later regret it. I have certainly had my share of negative experiences with invasive species here in Southern California in a climate that is not one of the worst or the best for invasive species. I am only thankful (at times) that I do not live in a more tropical environment where things can really take off. Bermudagrass, wild morning glory and some Agaves have been worse experiences than improper placement and control of bamboo, but bamboo is easily one of my worst invasive species experiences. However, with proper planning and a bit of work, this can be a ‘safe’ species to plant in ones garden. The following is a introduction to not only controlling this aggressive plant, but also some suggestions on picking the right species for your situation.
Morning Glory seen here in different settings obviously let run amok. Was about this bad in my own garden only I have no detailed shots
Agave americana spreads all over, often many feet from the original plant, often next to something else you don't want to uproot, and it is sharp and tough (left); right is my current out-of-control grape situation, my only really bad mistake in this last yard.
Phyllostachys nigra, aka Black Bamboo, was one of my big yard mistakes
Depending on the climate you live in, and the yard size you have, there are various varieties of bamboo to choose from. Those you that live in warm temperate climates should be able to grow most species of bamboo and those in tropical climates can virtually grow any species they want to. But if you live in a climate zone where it freezes regularly, you are pretty much limited to species of running bamboo. And running bamboo are the types of bamboo that require the most control (there is a reason why they call them running bamboo).
local bamboo sale showing many vaireties that are available (tall on left and short on right)
Bumbusa multiplex 'Alphonse Karr' is a nice colorful plant for most warm climate yards (left); Bambusa oldhammi is a huge bamboo that can sometimes fit in tinier yards (middle), but some bamboo need a LOT of room (huge yards)- right
When I first became interested in bamboo I decided I wanted to grow as many species as I could in my ½ acre yard, figuring that it was plenty large enough for dozens of species to be grown here and there. And had I selected the right species, perhaps I would have been correct. But I just acquired what was available- about a dozen clumping Bambusa and several running species. I knew runners were risky, so I planted them in the ‘corners of the yard where they would probably not get too involved in the rest of the garden. I quickly discovered some of these runners were pretty good at getting from one area to another in a hurry. One I managed to control with drought, and by not watering the surrounding soil, the plant only managed a few ‘breaks’ into areas I did not want it, and I kept it under control for a while. Another immediately showed up in the middle of the neighbor’s yard, despite the presence of a concrete wall between (turns out there was inadequate footing, along with small spaces in between the bricks). Another plant I put in the ground in a large plastic pot with 3 feet walls… only the plant had been growing in this pot already for a few months so roots were already at the bottom. This one was my worst mistake and I was still battling this one until I left.
This is a shot of Black Bamboo (Phyllostachys nigra) planted without barriers. Note the new culms shooting up some distance from the rest
Another shot of Black Bamboo spreading
Anyone who claims that runners can be controlled by just kicking down the new growths, or applying Round Up to the ‘escapees’ are overly optimistic, and should not be listened to. Get a barrier! And BEFORE you plant your bamboo.
My worst bamboo mistake of all was planting a bamboo called Marbled Bamboo (Chimonobambusa marmorata) that had an uncanny ability to spread over ten feet from the other culms- this one quickly shot into the neighbor's yard. Above is a large clump at a botanical garden (left) and though not a great photo, right shows a few culms shooting up so far from the main plant that they seem like unrelated plants (small sticks shooting next to the sidewalk)
Not every species needs a barrier, of course. Above are two of my favorite of all bamboo species- left is Chusquea coronalis, a wonderful fountain bamboo that stays in a nice tight clump; right is one of several species of 'blue bamboo' (this one is Himalayacalamus hookerianum). Both species are not big invasive threats and don't do any damage with their roots (or not much, at least) . These clumping species are harder to grow in colder climates, however.
but just because a bamboo is a clumper, like this Dendrocalamus gigantea, does not mean it might not need some barrier control. This massive species is one of the harder to control, even with a barrier, as its rhizomes are massive and can destry nearby structures. Plan ahead even when planting clumping species.
Bambusa oldhamii is one of the more popular large clumpers since it is so upright and slow to spread (left)... but slow does not mean it never spreads.. .this Bambusa oldhamii clump in a botanical garden takes up over twenty feet in all directions (right) and could use a border of some sort in a private setting
But if you like Phyllostachys species, or live where you can't grow clumping bamboo, you will definitely need some sort of control or you could end up with a huge clump of bamboo like this Phyllostachys nigra bory, which takes up nearly a football field sized area (and not more thanks to a road barrier, constant human trampling and gardeners knocking down the new shoots regularly)
Running barriers come in various materials from concrete, metal, wood to various forms of plastic. If you are looking at the real long term situation, plastic barriers are the way to go. Concrete eventually cracks over time and roots find their way through, though this can take dozens of years to occur. Concrete looks the nicest, though. Metal rusts and breaks down very quickly below ground and makes very poor barriers (and can be sharp and dangerous to work with). Wood, even very well treated, breaks down the fastest of all barrier materials. Plastics come in a variety of ingredients and thicknesses. High density polyethylene is probably the best material to use for rhizome barriers, at least for large and/or aggressive species.
These Phyllostachys plantings at the Los Angeles Zoo have a nice ready road barrier on one or both sides of these plantings, which seems pretty effective, but I wonder if there isn't additional plasting placed along side the road edge
This Bambusa multiplex is actually a clumping species, and road works exceptionally well to control this one... its common name is appropriately Hedge Bamboo
There are plenty of online sources of plastic rhizome barrier that you can look over these and decide yourself. You want something that will never break down, is too thick to ever be ‘poked’ through by an aggressive rhizome but not too thick to be easily worked with (‘easily’ is a relative term and usually means can be manipulated by several strong people, not that you could do it by yourself… realistically at least), and can be sealed at the overlap point effectively keeping roots from finding their way in between. Turns out that even this solution can have a limited life span and most companies recommend replacing these overlapping areas every now and then (of course they do… $$).
Below are several web sites showing rhizome barrier installation, prices and availability. Last link is to google images of rhizome barriers.
For more on putting a rhizome barrier, check the internet – ads abound for these products. And for general information: http://www.wikihow.com/Install-a-Bamboo-Rhizome-Barrier
Rhizome barriers also come in a variety of depths. I would personally pick the deepest one available, unless you are only planting a small runner. Three feet is the deepest most companies offer. When digging a trench, one must dig it so that there is at least a few inches of barrier above ground (too much is unsightly, often tripped over, and leaves too much room below for errant rhizomes to escape). If buried at soil level, rhizomes will find little impedance as they run across the soil surface and quickly re-root on the other side. But even at two inches above soil level, rhizomes will still manage to crawl over- but they should be visible and exposed enough to chop in half or deter in some way. So one still needs to pay attention to the barrier regularly when one grows running bamboos.
this is a shot of a plastic rhizome barrier around a Phyllostachys planting in a botanical garden showing a bit higher than recommended lip (though this makes escapees less likely to occur without notice)
This large population of Phyllostachys sp. in this botanical garden has a plastic barrier keeping it from spreading to the lawn (left); right is a large Phyllostachys in a private garden with a thick concrete barrier- looks nice and effective, but maybe not so permanent
When digging a trench for a barrier, it is best to angle the trench a bit, if possible, or dig it wide enough that soil can be added after the barrier is sunk in, to allow the barrier to somewhat lean away from the bamboo… this will encourage would-be errant deep roots to grow upward and be discovered. Barriers that are vertical or worse, lean the opposite way (inward) will encourage roots to grow deeper, and some of the larger species might still manage an escape route that way.
This unique concrete barrier is more long one long, thin concrete pot and controls this Phyllostachys species quite well, though not sure how long it will last. It is at least 10 years old, though.
Note that not all running bamboo are a big worry. Some of the smaller species are only minimally invasive (I have a few Pleioblastus that are really nice and grow only a few feet in any direction over a period of years). Still, if you want to keep these in check, they will still need a barrier, but one a bit less labor-intensive may work fine.
this Pleioblastus species is a pretty slow psreading species , and can even be mowed in the fall when it looks less healthy
Also note that not all clumping bamboo can be planted willy-nilly without concern of invasion. The massive clumpers will slowy spread outward, but will destroy most objects in their way in the process (driveways, walls and buildings) if not well controlled. And some Otatea, which are officially clumpers, are as close to running bamboo as a clumper can get, and may need a barrier, too.
Dendrocalamus asper is one of the popular and common clumpers grown in botanical gardens, but could use some control in a private garden (unless you happen to have an enormous one)
Otatea acuminata aztecorum (aka Mexican Weeping Babmoo) is an incredibly drought tolerant and beautiful species.... but for a clumper it tends to spread rather rapidly... this clump in a botanical gardens is nearly fifty feet long and pretty wide (would be a lot wider if not for the road barrier)
One should also be concerned about a few other bamboo characteristics before planting them in your yard. The first thing to consider is size of the desired bamboo and the size of your yard. Some species are not suited for small yards, no matter how well controlled. Bambusa vulgaris, for example, will grow very tall and arch laterally to virtually shade out nearly a quarter acre from the sun making it difficult to grow much of anything but deep shade growers below.
Bambusa vulgaris can be a huge, shading plant, unacceptable for most gardens. Also, if you live in a windy zone, bamboo may never look good (right)
Climate is another thing to consider, obviously, as many clumpers cannot survive freezing temperatures. For those living in snow-frequented climates, running bamboos may be your only option. Drier cold climates may permit less intensive barrier construction… but serious rhizome barriers will be needed in wetter climates, particularly if you live in a high rainfall area like most of these running bamboo thrive in. Those living in dry deserts, particularly where winds frequent, will not be happy with the looks of their plants no matter how much they water them. And those with limited water sources should rethink growing bamboo as most are quite thirsty plants.
Phyllostachys sp. will grow well in a wide range of climates (left) and even tolerate freezing; Thyrostachys siamensis (right) is a much more tropical bamboo and does not like it super cold
Availability of sun and shade may also be important. Shade is important for many smaller and colorful species, and some will not thrive unless they are grown in some shade. And others will only grow well if they can get constant sunshine, and will wither in shade.
These two bamboo, for example, need full sun or they will not thrive or achieve the wonderful color (left) of their full potiential. Left is Giganticloa atrviolacea and right is Thryostachys oliverii. Nearly all the other species shown above are sun loving genera (Phyllostachys, Bambusa, Dendrocalamus etc.)
These bamboo will not do well in full sun and some shade to stay happy, particularly here in Southern California where the sun is brutal. Left is Thamnocalamus spathiflora and right is Farigesia nitida, aka Fountain Blue Bamboo (one of my favorite)
Above are two more species that do not appreciated direct sun, either (same goes for most, but not all, dwarf bamboo species) Himanocalamus tranquilans (left) and Sasa tranquilans (right)
Here is a link to the American Bamboo Society plant list, that not only shows availability, but also some of the sizes and sun/shade needs of each species: http://bamboo.org/BambooSourceList/BambooPlants.php?G=All&M=1&Button=FIND&U=I&S=1
Another thing to consider are other things in the yard. For those with pools and cactus gardens, bamboo are NOT good nearby plants as they endlessly drop tons of leaves year round. I will probably have to remove my Bambusa oldhamii since I am constantly removing gobs of paper leaves from the crowns of all my succulents and cacti (not easy to remove from cacti). And my bamboo is in a corner of the yard… still the leaves get everywhere. Few trees can compete with bamboo for continuous leaf drop.
these shots were taken of areas of the garden somewhat near the bamboo AFTER cleaning out all the leaves a gazillion times already
And lastly, be sure you really want bamboo. Few plants are more difficult to remove permanently from your garden than bamboo (even clumping bamboo can be persistent). These plants have roots and rhizomes like iron and can be very hard on saws and shovels. Runaway running bamboo sometimes are nearly impossible to completely get rid of, even with gallons of glyphosate, digging, chopping and tossing out. If in doubt, best to keep bamboo in a pot- many make very nice potted plants.