I have started some bamboo seedlings indoors from seed and was curious to know if they will continue to grow in their first year. There are some clumpers and runners. They shot up at first to about 5 inches now basically give no appearance of any further growth despite being healthy looking and happy. Depending on the type they either grew one culm or some grew an initial culm then a second and one type grew a single branch off the main culm. But then nothing else for a couple of months now. Half are under grow lights in a very warm room since initial sprouting with 12 hour "days" and half have been spending over a month with just window side light on a south side of the house. No difference between the two that I can determine although the ones with the most direct sunlight are a little paler in colour on the leaves. I'm starting to wonder if that's all they'll grow this first season. None are higher than about 5 inches or so and if I should continue to baby them in pots until next year (they are destined for planting outside). I've tried hardening off one of each type and they show no ill effects, I'm up to a full day now out on a protected porch. But no new growth there either. Any info or links appreciated.
I should also add that they normally will branch out in the second season, if they don't in the first.
My understanding from some more research I've done is that seedlings will grow several culms as weather permits until fall and don't follow the normal yearly growth cycle until *after* the first year. I guess I'll find out soon enough. :)