Running bamboos shooting for the 2nd time this year

Normally running bamboos—varieties with rhizomes that spread instead of forming a clump—produce new shoots in the spring as soon as the weather gets warm enough. In our area, this typically means March into early May. See these posts from earlier this year: 1 2 3.

Each new shoot quickly turns into a culm (technically not called a “cane” until it has been cut down) and forms new branches. The branches, in turn, grow the leaves that produce energy through photosynthesis.

As spring turns to summer, running bamboos focus their energy on rhizome development, storing energy for next year’s crop of culms.

That’s the normal development cycle of most running bamboos. However, four of our running bamboos—which had already gone through their regular shooting cycle in April—are now shooting again. I don’t know exactly why that is. Like all running bamboos in our garden, they are confined to containers. That, in itself, creates an artificial environment which affects plants in often unpredictable ways. In addition, September has turned out hotter than anticipated, with temperatures approaching and hitting the century mark this past week (it was 100°F yesterday and close to that today).

I’m very curious to see how these shoots will develop. It’s possible they’ll be weak and floppy, in which case I will remove them next year. But whatever the case may be, these four plants felt it necessary to produce additional shoots so I’ll let them do their thing for now.

Phyllostachys aurea ‘Koi’
Recently transplanted from a pot to one of our stock tanks. Maybe this specimen is shooting because of all the extra room it now has available?

Phyllostachys aurea ‘Koi’

Phyllostachys aurea ‘Koi’
The green rectangles indicate the new shoots.

Phyllostachys bambusoides ‘Castillon Inversa’
This shoot is emerging at an extreme angle and is thinner than the existing culms. Most likely, it’s what’s called a “whip shoot,” i.e. a rhizome that instead of continuing to grow underground, turns upward and becomes a culm. This situation is different from the other two bamboos (see below) because this shoot is emerging in the middle of the container, not along the edge.

Phyllostachys bambusoides ‘Castillon Inversa’ (right),
Phyllostachys aurea ‘Koi’ (left)

Phyllostachys bambusoides ‘Castillon’
These new culms are at the very edge of the pot so in all likelihood they are rhizomes forced upwards when hitting the container wall. This specimen will be moved to a larger pot just as soon as it cools down a little. I don’t like working in the heat!

Phyllostachys bambusoides ‘Castillon’

Phyllostachys bambusoides ‘Castillon’ (right),
Phyllostachys bambusoides ‘Castillon Inversa’ (left)

Phyllostachys viridis growing in a galvanized steel tub. As with the ‘Castillon,’ these new culms are at the edge of the tub. If the plant had been in the ground, they probably would have continued to travel underground as rhizomes. It’s still amazing to think that what you see here started out as a 15 inch length of rhizome (no culms at all) a fellow bamboo enthusiast mailed to me in April 2010.