My Fastuosa Viridis has only been in the ground for 2 full growing seasons, yet it's making a break for it. found a rhizome that had snaked to the surface almost 3 meters away!!!! In the UK I didn't think that kind of spread was possible from such a small plant.

So Im currently digging a trench to protect the neighbours on one side only. I'm going down 600mm, and will leave it open (explained later) so as we'll as monitoring any rhizomes coming across the void, I can also plunge a spade an extra 200mm in the bottom of the trench, making 800mm of detection. I hope it doesn't go deeper than that..... Anyway...


The trench, dug by hand, is 125mm wide, as mentioned, I want to leave it open but I am concerned it will collapse in on itself over time. I'm toying with the idea of using 100m polystyrene sheets to fill the void loosely, preventing the earth on each side flling in. They won't be effected by rain, and can be easily lifted out several times a year to check on Rhizomes. I could lay a thin layer of bark clippings on top to disguise the unsightly whiteness.

So.... Any views on this? Cheers.

If you are concerned about rhizomes getting into the neighbor's yard, why don't you try putting down a rhizome barrier as a secondary measure to rhizome pruning? You already have a trench dug so it should be pretty easy to install a plastic barrier.

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http://stevespeonygarden.blogspot.com/

Hey steve.

My reasoning was that a barrier may fail in time, but a trench won't. Also no possibility of directing rhizomes downwards, and as mentioned i can monitor 800mm down but only need to dig 600mm.

Ive never had to contain before, so this trench is a first.

Out of all my boos, some 20 or so, this has been far and away the most aggressive.

Your relative geographical location would be interesting info. I have SA fastuosa viridis as well. The planting in the sunier place is moving right along.

As to trench vs barrier, it really does depend on how much attention (year after year) one pays to their plantings. If you think you will manage trench at least once a year, it will probably work. Would not work for me as I am easily distracted and have a lot going on.

Hi,

I'm faced with a similar problem this year (Confining several Bamboos to the property line) and I think it comes down to a question of money vs. work.

If you properly install a good quality 2mm HDPE Barrier with a width of 1m the chances of escaping rhizomes are pretty slim, especially if the confinement is open.
From what I've read about HDPE as a barrier it should generally last at least a decade. The obvious downsides are that HDPE isn't exactly cheap and you will still have to prune rhizomes.

Your approach is very cost effective but has to be maintained regularly to ensure that nothing escapes. As opposed to having two problematic areas where rhizomes may escape to the neighbours the entire trench is vulnerable.

One more thing you might want to consider is that as the rhizomes penetrate the polysterene it will be damaged when being removed later...

Of course you have the advantage of already having a trench into which you can install a Barrier later on so I'd probably stick to your method for now and see how much maintenance work is really required.

Hi Nick

Yes, i did consider that I will need to pull the polystyrene out and there could be a great sharp rhizome through it, holding it in place. Cheap enough to replace though.

I have no experience in either method of containment, so i speculate only.... But i would rather view the trench several times a year to check whats happening, rather than a barrier you cannot see, which may be breached or send a rhizome down and under, and the first time you know about it is when a culm pops up in neighbours garden.

I suppose the only way it fails is if you dont maintain several times a year?

If you're planning on leaving the trench open (since you said something about "seeing" the rhizomes) I think you'll have problems over time. My open trench filled itself in after only one full year -- the sides eroded. I have heavy clay soil too. So now mine are filled with mulch. I need a few more years before I make a decision on if it's better or not.

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Alan.
My blog: It's not work, it's gardening!

Alan, that's disappointing. I have heavy clay too and hoped the polystyrene would help keep the ttench in shape. It could be the sides just collapse and lock the polystyrene in place.

If yours is filled with mulch, how do you rhizome prune? Do you just cut right through the mulch or scoop it out etc?

If you have very hard clay soil, you could just buy a bamboo slammer, and rhizome prune on that side of the bamboo annually preferably right after shooting season so the rhizomes going in that direction lose their viability.


I have always thought about getting the slammer however most bamboos simply haven't been aggressive to the point that I needed to do any rhizome pruning even after 4-5 seasons of growth. Aureosulcata spectabilis has however shown superior spreading capability as it produced a nearly 3M (9ft) rhizome despite efforts to slow it down by making it produce whip shoots. This one is also very close to the property line to the point where the rhizome almost crossed into the neighbor's yard. I ended up digging it out and throwing it into one of my compost piles to see if it does anything as a division taken last fall.

I'm not sure if it will become less aggressive as it gets larger like the other phyllostachys, but it appears to be the only one that will require control.

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http://stevespeonygarden.blogspot.com/

I use a mattock to dig through the mulch. A lot of the mulch gets dug out of the trench during this process, but it's easy enough to put back in. It does need to be replenished each year too.

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Alan.
My blog: It's not work, it's gardening!

This was taken a couple years ago- maybe 2010. It's the only runner I own that has a trench all the way around. Putting in a barrier at this point would be quite an effort- the shape of the bed, where would I put all the soil as I excavated, etc.

You can see that the fence between the neighbors is right up against the bed. I used a sharp shooter to dig 2' down, cutting/pulling rhizomes as I go, and each year threw some of the soil up into the grove. Over time, this has elevated the bed way above ground level. I dig the trench 2x per year- Nov/Feb (in Texas, not required in colder climates), and fill in with mulch. The mulch decomposes, and gets added to the grove as well.

Plan the eventual mature size/shape you want for your grove when you do your first dig. Plan for growth, make it a cool shape and not just a square (except for fence line).

It is way easier than edging your lawn every week- so when you think of it, your just growing a really big grass. I think a freestanding grove is a thing of beauty, but in an urban environment, you have to put in the work to keep that sucker contained.

One warning about the "dig the trench and throw the soil on top of the grove every year" method: you'll eventually have rhizomes that are buried quite deeply. A friend in town does this and has been for 15+ years, and digging out these plants now (for removal or relocation) is quite painful.

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Alan.
My blog: It's not work, it's gardening!

I'm surprised that new rhizomes do not grow up into the higher soil and eliminate that issue? Conversely, it might be easier to kill off if they stay that deep should one want to kill off a planting...

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/

They do grow seem to grow toward the top, but you end up with an 18" thick mat of rhizomes with some really woody mass toward the bottom.

He did limit the amount of space each plant got to a pretty small area (maybe 6' diameter at most), so that may have something to do with it.

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Alan.
My blog: It's not work, it's gardening!

Yeah, that small space probably doesn't allow them to rise up and continue on their way but even in my groves that aren't mounded I won't attempt to make any divisions until the colony has well cleared the dense clumping area around the initial planting site - 6' diameter is too small for me to dig in. Too congested and tough to get pieces of rhizome as long as I like on the Phyllostachys, which means that it is several years b4 I start making divisions unless a runaway rhizome produces culms early on.

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Brad Salmon, zone 5b/6 Southern Indiana
Winters -20 to -25C. Summers 30 to 35C , humid. 115 cm annual precipitation, frost free from May through early October. 259.3 meters elevation. Growing 150+ species. http://www.needmorebamboo.com/