Advice
RHS Help & Advice
Dividing grasses and bamboos
Grasses from cool climates such as Deschampsia, Festuca, Helictotrichon and Stipa come into growth in late winter and flower before mid-summer.
They are divided in autumn or late winter to early spring. It is often preferable to divide frequently to avoid the difficulties of congested roots and to keep plants growing vigorously.
Grasses from warm climates such as Miscanthus, Panicum, Pennisetum and Spartina come into growth in late spring, flower after midsummer and are usually cut back in late winter. They are best planted or divided in late spring. These grasses do not usually need such frequent division.
The
best method for division is to lift grasses from the ground
and split using two forks inserted back to back in the centre
of the clump or split through the middle with a spade. Some
grasses have tough roots that may require using a sharp knife,
saw or even an axe to split them apart. Small grasses such as Hakonechloa, and many sedges, can be split by tearing lifted clumps apart by hand. Cut down the foliage
of pampas grass before dividing - making sure you wear stout
clothing and gauntlet-style gloves. Keep pieces as large as
possible in most cases.
Water in new divisions, keep the soil moist and protect them from strong wind or sun until established.