This bamboo has to go... or does it?

As you may know from reading my previous 400 or so posts, I love growing bamboo. The problem I have right now is that I'm limited in planting space, so many of the around 50 varieties I grow are kept in pots. I'm constantly evaluating the ones that have been planted in the ground though, looking for signs of weakness, poor winter hardiness, or any other reason to remove a plant and free up its location for one of my potted species. I did this last summer when I removed one bamboo and planted another.

I've been keeping an eye on this species (Semiarundinaria fastuosa 'Viridis'). It did better than I hoped last winter, staying about 50% green. It's not sizing up for me very fast though (it's about 8' tall right now), and it's reported to have rhizomes -- the underground "runners" that allow the bamboo to spread -- that grow deeper than usual, making it difficult to rhizome prune and keep the plant from taking over.


This plant just started shooting in the last couple of weeks, and upon first look the "deeper rhizomes" description seemed to be true:

Coming up under my weedblock fabric. I'll never use this stuff again.

I had shoots coming up outside of the specified area -- it looked like my rhizome pruning did not work!

Since I can't have an out-of-control bamboo in my garden, this decided it for me: I was going to remove this bamboo completely!

When I started looking closely though, I decided to do a little more checking of the wayward shoots to see exactly how deep I'd have to dig to get this plant out.

Since the plant is growing on a slope, I had created this little loose stone retaining wall:

That rock wall had been creating problems -- not letting me rhizome prune easily, falling down, getting buried under mulch -- so I pulled the stones out and used that as a starting point:

You can see the shoot to the left of the rock wall's former position, and that's the first shoot I'll investigate. Digging a little, I found its rhizome:

It was only 4 or 5 inches below the surface, so in this case the rock wall was definitely the problem -- without it I could have pruned this easily.

Next up these two, which appear to be coming from the same rhizome (but not the same rhizome as in the previous photo):

They were, and the rhizome was about 5' long (past the point where it should have been pruned last year).

It too was only 6" or so below the surface, which should have been cut when I pruned. So I was beginning to think that the problem was not that the rhizomes were too deep, but that my pruning was not very good.

Thinking back, this is a tough plant to prune in the fall, as there are a couple of large ornamental grasses on each side of it. Their sharp-edged blades make it tricky to get back here, and it may be that I skipped the fall pruning last year, or meant to get around to it but eventually forgot.

This plant was putting up some decent shoots inside its allotted area too, so it will most likely be taller than it was last year:

So I decided to give the plant another chance, and instead of digging it up I would just remove the escaped rhizomes.

As I worked my way around the plant making my shovel cuts, feeling the snap of rhizomes being brought back under control by my spade's keen edge, I created a little trench. Trenching around a bamboo is one way to control it -- you fill the trench with mulch or something similarly light, and when the rhizomes grow into it, you just cut them off. This isn't that type of trench. It's just a marker to show me where the plant should stop.

The little trench I was making. The rogue shoots are on the right.

When I got to an area that had wayward shoots coming up, I made sure I felt the snap of its rhizomes being cut. I was still concerned that there could be some deep ones that my spade couldn't reach. This one didn't produce a snap:

You can see the curved shovel cut in the soil at the left. This had me worried, so I dug around a little to see what was going on:

It turns out that the rhizome wasn't deeper than usual, but it was growing at an angle and my shovel hadn't hit it yet -- my next cut would have though.

As I was finishing up the trench, I noticed a disturbance in the soil -- a mole was digging its way right into my trench!

So I waited quietly for a few minutes, and before I knew it, I had a mole in the bucket!

MoleMeter 2011 mole capture count: 3

It's weird seeing a fluffy, dry mole. Since I switched to the water method a few years ago they all come out wet.

Let me out of here!

With the mole break over, I finished the trench and the plant is now back under control!

I'll ensure that I don't miss the pruning this fall (or in late winter), and I'll evaluate this guy again next year. I'm not going to put the retaining wall back, nor will I create a "box" here as I've done with other bamboos. Boxes tend to make rhizomes go deeper than usual to escape, and since I'm not certain yet that this guy's rhizomes won't go deeper anyway, I don't want to exacerbate that.

I was kind of excited about having a place to plant one of the other bamboos, but I'm also glad that this one may make the cut. It's got a very different look when compared to the other bamboos over here, and makes for some nice visual variety.

Now I'm just curious to see how much height it puts on this year. I expect a couple of feet at least, and will be disappointed if it's less than 3' taller this year.

One very interesting thing I found when digging out one wayward culm from last year: it had produced two shoots from its nodes!

This is unusual because the shoots are supposed to come from buds on the rhizomes. Maybe this isn't too strange with this genus (Semiarundinaria), but it was really surprising to me.

I've got one more Semiarundinaria that has escaped its area too -- but I'll tackle that later this summer once I decide exactly what I'm going to do with it.


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Gerhard Bock (Succulents and More)  – (June 13, 2011 at 12:01 PM)  

Great post. It's always interesting to see what goes on underground, especially for a guy like me who has to keep running bamboos confined to containers.

Rock rose  – (June 13, 2011 at 6:06 PM)  

That sure seems like a lot of work. Your mole catch reminds me that we had a mole in our garden in Chesterfield. It undermined my garden beds destroying plants and no doubt eating my worms. We got a mole trap. Nasty contraption but it did the job.

Dave at Gardeningonadime  – (June 13, 2011 at 10:06 PM)  

Thanks for the "underground" view of your bamboo. We're hooked on clumping bamboo, but we also have a few runners (in pots, on pot casters, on a concrete patio). Around here, with our heavy summer rains, running bamboo can get wild in a heartbeat! You're a brave gardener.

Alan  – (June 14, 2011 at 7:44 AM)  

Dave: it's not difficult to control most running bamboos. It just takes some work with a spade once or twice a year. Cold-hardy clumping bamboos take so long to gain size. Runners are where the action is! (Unless you're lucky enough to live somewhere where the tropical clumpers can be grown. Those are the BIG ones!)

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