If I were you, I'd plant more than two species -- not so much out of concern about flowering (although that's a legitimate concern) -- but because you've got the room to enjoy a variety. However, I would argue against intermixing as you may end up with one outcompeting another. Instead, plant in discrete areas and use rhizome pruning to maintain the boundaries of each grove.

Intermixing species is fine as long as you are willing to selectively thin out the more vigorous species to keep it from taking over. I have a mixed grove of Phyllostachys nigra and P. bambusoides castellonis that I have maintained for over 10 years. Of the two, nigra is the more vigorous, so I cut out more of its shoots, and thin out more of its culms to keep it at rough parity with the less vigorous castellon.

We went to Midatlantic bamboo in VA to see their groves. They are all separate and each grove is a beauty in itlsef. We'll go back in March for two more large timber varieties.

With limited space on my 1/8th acre lot, I have to grow different species pretty close to one another. It takes a lot of careful monitoring, but if you plant species that have good identifying characteristics, it's not that hard to watch for dominant species and keep their growth in check.

I have a hypothesis that if you plant more starts in an area the resulting grove should have smaller clums in the end. Imaging a 10x10 area. Now plant one bamboo and treat well, how big do you think it will get. Contrast that with planting 100 bamboo starts of the same species in that one area. So you have one bamboo per square foot. You will fill in quicker but the resulting grove will consist of many separate competing plants instead of one big interconnected one.

If you could identify each separate plant and kill them essentially thinning each year then you could end up with a single plant in the end. For instance you start with 100 but kill half the plants each year. Then I think the final result would be larger clums than if you left them all alive.

Well how could you do that? After all once they get all tangled you cannot tell them apart.

Solution, plant different species and then either kill them in succession or let them outcompete each other.

Example, 10x10 foot area. Of course 100 plants is too dense so plant four species which are easy to tell apart, one of which gets real big. Within a year or two you have a nice dense hedge. Now you can start killing the species off one at a time by pruning out the culms of victim number one, then two and then three. All the while maintaining the density of your hedge. You don't even need to work on a single victim at a time. You can be most heavy handed on any victim species that get close too, shade or interfere with the one species you want to keep. This may mean one victim gets hardest hit or it may mean all three get wacked to the same degree.

Of course this is all armchair philosophy... or is it?

So I might not be too concerned if one species outcompetes another in a mixed planting. Might just be what the doctor ordered.

A running bamboo grove, whether planted with one plant or 100, does compete against itself. But if left to its own, it will run and claim more ground and more until it flowers. 1 plant of running boo in a pot will show the competition more clearly by ever-producing rhizomes and exhausting the resources.

You realize a bamboo is a single plant, correct? In the sense you are using the word compete I can say the following: "A tree, whether planted with one plant or a 100, does compete against itself". What does it mean to compete against oneself?

Sure one culm of the same bamboo plant will shade another of the same plant, but the same happens with tree branches. That doesn't seem to stop single trees from growing to maximum diameter, while trees crowded together grow thinner trunks.

If your talking about clumping bamboo, I would concede to agree. But comparing the running bamboo to a single tree is uncomparable. Running bamboo is a colony plant with a mission to smother everything to evercreate its own monoculture forest. If you would plant many plants of the same clone/species, they would all have the same genetic vigor and be spaced that close together would have root grafts that interconnect to become one big mass.
One bamboo in contained area will in the shortterm get to bigger size because its roots have lack of competition, unlike shoving 100 clones in the same area, but given enough time in the small contained area it should make no difference.

I'm talking about running. Is that info on root grafting an established fact or an assumption on your part. In those species of trees that do root graft the process takes place via the fact that the growth layer on the roots surronds the root and therefor the roots grow in diameter. When two roots grow past each other touching as they grow in diameter their outer growth layers become meshed at the boundaries of the ever increasing area of contact.

Bamboo doesn't grow that way.

The rhizomes are technically not roots, the growth layers are between the node on the interior, once a rhizome enlongates the growth stops, the rhizome does not increase in diameter at that point, and during the time of growth the rhizome is covered with sheaths which would prevent any contact with another rhizomes growth layers.

The real roots of the bamboo also grow differently than tree roots. They come out of the rhizome at pretty much full diameter and don't expand like tree roots. That is why when you dig up a bamboo the rooting pattern looks so different than a trees. It looks more like a brush than the branching appearance of tree roots.

I don't think a 10x10 (100 sq feet) foot area of my example is such a small contained area for a running bamboo. I had a 12x4x20 trapozoidal area (160 square) which I planted a 1 Vivax and 1 Bory in and they got very big. They were in there for 12 years and each year the clums were bigger, not smaller, which I count as evidence they were not crowded. They had filled in the entire area at 5 years but continued to get bigger for the next seven years.

The poster of this thread has an Area of 100'x50'. Hardly a space where single bamboo will get crowded in for over twenty years or more.

I do think eventually a bamboo in such a space would get crowded and the culms would decline in size. But I think it would follow a curve. A first the culms would be small because the plant is young, then as it took over the area the plants got bigger the culm size would increase, there would be a point at which the plant would become crowded and the culm size would decline. What I am saying is that if you put too many plants in at once you miss the full range of the upswing to largest sized culms because you reach the crowding point long before you get those culms.

I have noticed this effect at the grove over at Stony Brook university. The area that has the oldest clums also has the most crowding and the clums just are not as big as the ones in the newly colonized areas. By newly, I mean like sixteen years ago, so they are not exactly fresh areas. In fact in the old areas the biggest clums have died out and are replaced by new clums of smaller diameter. Old places where I remember very big clums now have less impressive ones.

I read that a management technique used by some grove managers is to cut out the smaller diameter clums in a old grove and to fertilize it. This brings the average culm diameter up for obvious reasons (after all if we shot all the midgets in the US the average height would go up), but it also causes the new culms to come in at a larger diameter. Fertilizing alone does not give as impressive results.

I am assuming that cutting down the smaller diameter clums tends to cause weaker smaller diameter rhizomes to be starved out, thus thinning out the grove. Even in groves established by a single plant the original mother rhizome eventually dies splitting the grove into several intermingled but separate plants. Thus with very old groves you would get the same effect of several competing plants that I was talking about.

Constantly thinning small diameter culms would have the effect of selectively destroying some of the plants, thus making for fewer plants in the same area. An analogy would be in a prisoner of war camp, if you only had so much food to go around and had to reduce rations, you could do it one of several ways. If you reduced all peoples rations that would be like cutting culms of all diameters. However if you reduced rations for only the weakest and scrawnyest you would tend to cause their early demise, leaving the more healthy alive. You could even accelerate that more by taking rations away from the thin ones and giving extra rations to the big healthy ones.

So as you destroy the thin clums you would be depriving smaller diameter clums of their food source, you might not get every clum they put up since they might have put up a big one. But then the next year due to the lack of nourishment those rhizomes that had the most small diameter culms would put up even smaller clums. Meanwhile, by opening up the grove you let more light get to the other bigger rhizomes clums, making them more likely to put up yet bigger clums. This acts as a feedback mechanism to cause smaller rhizomes to get smaller and bigger ones to have the way cleared for them to get yet bigger.

Sorry for the gloomy death camp analogy, I couldn't think of a better one. Perhaps I shouldn't have used it at all. I'm not sure it was neccesary to get my point across.

Of course this is all based on the assumption that everyone wants large diameter tall culms. A worthy assumption, I hope. However if you want tight impeneratrable barrier you should grow a bamboo that puts out branches close to the ground like golden bamboo, plant many plants very densely, snap off the larger culms sprouts, and perhaps dig into the ground and sever a few rhizomes to ensure you get multiple plants. This way you have lots of closely spaces smaller clums in your barrier, or hedge.

Thanks for clarifying your statement. I better understand you point and it is well taken.

Ikz5ia,

Thanks for not getting mad at me. I am glad I was able to communicate my position without getting you riled.

I tend to communicate poorly on the internet because I find writing to be so odious and laborious a process. That's part of the reason I didn't go back and remove the labor camp example after I had written it and realized it might make some people upset. I had invested too much time and didn't want to rewrite it with some other analogy. Sorry to those who might have found it upsetting.

I tend to write as I speak and I have a dark sense of humor which doesn't come across well when writing. When speaking I tend to give off clues that I am joking, such as voice tone. I sometimes forget that writing is a different medium and get myself in trouble. So I tend to get into alot of disputes on the internet where the main focus is ego instead of the question at hand. Often I don't know what's going to push someone elses buttons. I was afraid inadvertantly push yours when all I really wanted to do was communicate my ideas.

Thanks for taking things the right way.