Really looking forward to the next shooting season.
While not a fair comparison as my plantings are from whip culms and didn't seem to grow much in its first season, they do have the benefit of root freedom and not being confined in a pot.
The two whip culms are planted side by side originally with intention to only keep the stronger one of the two, depending on how they perform next year. But, I am having second thoughts. Will the competing culms be a positive or negative? Is it worth the risk of damaging the plantings if one is removed?
When I grew lots of moso seedlings in a single pot, it seemed like 1 of them will eventually choke the rest of them out, and I believe the same thing will happen given that the parvifolias are competing in a confined area. I think once they start shading out each other, there should be a negative impact on both of them, but the one with the slight edge in vigor will continually get more light resulting in more growth the following year, and that cycle should repeat until the stronger division wins out. The problem is that after a while, you won't be able to tell which shoots are coming from which plant, but I think eventually, one of them will continue to produce bigger culms in comparison to the other. This would probably be a better experiment if it were different cultivators of the same species which have about the same size and vigor, but look different such as vivax aureocaulus vs vivax huangwenzhu. Over a 10 year period, I believe the result may end up about the same whether they are allowed to compete or one gets removed.
If you do intend to move one of them, one way to ensure that rhizomes haven't crisscrossed the center is to take a pick, and dig for rhizomes between both plants, then re-direct those rhizomes back the other way before shooting season. Chances are, there may not be any intersecting rhizomes yet as bamboos at that size typically don't produce that much rhizome mass.