Spreading varieties can be successfully restrained by installation of an effective barrier. In my experience the shoots/runners they send out aren't very deep, typically only a few inches below the surface. I had Phyllostachys aurea in a bed with deep, timber edging for about 20 years with no problems. I then had work down on the garden the muppets removed the timber without telling me. Within 12 months I spotted shoots coming up in the lawn so decided to remove it completely. That was a bit of a task, but by following the runners from the main plant I did manage to get virtually all of it out. I did see some weak growth in the lawn for a couple of years but regular mowing killed that off. No further problems, now about 7 years on from the removal.
I had a similar raised situation PnD, hard to describe, but sort of a dry bit of a hill, very little topsoil, between 2 paths. I planted 6 or 7 of the clumping varieties, and the famous sasa palmata, which runs everywhere. 12 years later, it looks fab, but the sasa hadn’t become any sort of issue. It’s a really challenging position for any plant, and too dry really for bamboo. You could see the roots running then coming to the surface as they went down the slope.
I found all of them easy to propagate. They did ok from chunks cut off, runners cut off, and even just stems cut off.
I'm looking for a solution which won't require constant attention and/or concern, so almost certainly it'll be a clumping variety - also not keen on having to embed barriers, and then worry about how well they are working...
Here's a photo of the proposed location - the raised bank is around 750mm to the very top of the mound. What are the chances of even an 'invasive' variety going down further than this, and then sideways...?
@PnD. As I understand it, the roots to stabilise and feed the plant go down. The rhizomes are the means of spreading, growing sideways and rooting at intervals, the new shoots grow up from the rhizomes. The rhizomes are not deeply buried, so clearing an inch or two of soil from the surface should expose them. Ours is in a very small slightly raised section at the back of a border, so your planting area should be fine.
I'm really sorry, I can't remember which variety we have. It's one of the few plants I didn't keep a note of.
@PnD, your raised bank looks fine. Bamboos are shallow rooted, like grass, and won't burrow deep down to that area below. Your rendered wall at the back and brick retaining wall at the front will form an effective barrier - I have bamboo growing in a similar situation. I chose Phyllostachys aureosulcata "spectabilis" which, although classified as non-clumping, behaves well in the UK climate and does not "run" aggressively. It has mellow yellow canes with an attractive vertical green stripe. I've grown it for over 15 years now in two different properties and it has not caused any problems to me or my neighbours. Ideally this variety likes a sunny position but mine gets only morning sun and is doing well. Keep your new plants well watered while the roots are establishing and feed with handfuls of blood fish and bone in spring and again mid-summer. Don't clear away the fallen leaves - they add extra nutrients to the soil. Good luck!
We we have got black bamboo and golden bamboo. The black is much better behaved and does not wander too far. But the golden one loves our neighbours garden and goes through all the barriers in place and comes up big and strong next door. We do remove the canes for them. I would never grow bamboo again even though it looks so lovely, but a little plus side is that you get some lovey canes for your plants.
We (and next door) have an inherited bamboo. I think a phyllostachys and it is indeed pretty invasive. As @Plantminded says they are shallow rooted and we have successfully restrained it inside a rhizome barrier. We had to remove the runners first which were spreading out into the lawn. This year a rhizome managed to get around the edge of the barrier next to the fence and travelled a couple of metres before shooting up a cane! Bit of a pain but not too much trouble to remove.
I wouldn't be concerned about your boundary wall, but I would worry a little that the rhizomes could damage your retaining wall if it is dry-stone construction as it looks? If you don't want to dig a barrier in, an alternative is to add a trench a few inches deep around the plant, and check several times a year for escapees to cut them off. I think the barriers are far deeper than really necessary- we cut our down to about 9-12” I think, so it wasn't too much digging.
Posts
I'm really sorry, I can't remember which variety we have. It's one of the few plants I didn't keep a note of.
I wouldn't be concerned about your boundary wall, but I would worry a little that the rhizomes could damage your retaining wall if it is dry-stone construction as it looks? If you don't want to dig a barrier in, an alternative is to add a trench a few inches deep around the plant, and check several times a year for escapees to cut them off. I think the barriers are far deeper than really necessary- we cut our down to about 9-12” I think, so it wasn't too much digging.