I have a Phyllostachys vivax huangwenzhu which I planted from a 10 litre pot
two years ago in NW England. I removed a loose rhizome with culm at the same
time and potted it . Both plants are doing well.

I want to create some more plants by the same method. Could any one advise
when is the best time to remove running rhizomes if I want them in some
quantity to make a screen? Should I take them them this year as they appear,
or leave it another year until the runners might be more abundant?

Which method would produce the screen most rapidly?

Justin

About a month before the new culms emerge is when I have the best luck
with rhizome division of Phyllostachys.
Be fanatical about not letting things dry, I like to work in the rain.

You can divide you Phyllostachys at any time - Ideally you want to avoid causing any disturbance whilst shooting as this causes the new shoots to 'abort'. If you need 'loads' of them for a screen hedge, then you will probably be better off by extracting rhizomes and placing them lengthways in a tray. Place the tray in a propagator, and let them sprout. Leave the tray to continue sprouting for a year, until you have a reasonable 'mat' of shoots, and then chop them up into 6 inch squares. Each of these 6 inch squares should give you a new plant, and can probably be divided further on a yearly basis.

If you only require 2 or 3 other plants then continue with 'splitting.' Clean slices are better for the plant and cause less disturbance than 'teasing apart'.

HTH

If teasing apart rhizomes, you'll get better survival rate, better
growth from 2-3 year old rhizomes than from this year's rhizomes. Look
for plentiful roots and healthy shiny buds.