How to Prune dwarf bamboo?
Remove weak, dead, damaged or spindly stems in spring. Cut out any flowering shoots promptly to discourage more from forming

dwarf bamboo · Pleioblastus pygmaeus
Also known as: dwarf fern-leaf bamboo
Grow in fertile, humus-rich, moist but well-drained soil, in full sun or partial shade. Protect from cold drying winds. May remain clump-forming in poor or dry soils but can become invasive in warm, moist or favourable conditions; see bamboo control and bamboo cultivation
Remove weak, dead, damaged or spindly stems in spring. Cut out any flowering shoots promptly to discourage more from forming