Our sole clumping (non-invasive) bamboo, F. robusta, is finally showing new life, after buying and planting in April 2010. Two Summers of nothing, this Spring proves to be different with many new shoots much taller than the original ground cover we planted. Once really established, this bamboo can grow to 12-17 feet. This type of bamboo also has two growing seasons, early spring and August/September. This is the first Spring to see anything, and I think last September it did a little. That activity made me think that this, and all clumping, shot in the fall. Live, read, and learn. This species also holds onto the sheaths until mid Summer giving it a neat looking pattern.