Fountain grass vs Oriental fountain grass

In Central Europe winter hardiness varies between cultivars and is borderline in cold, wet winters: in heavy, waterlogged soil part or all of the crown can die, so plant the crown slightly high, do not cut it back in autumn (the dry foliage protects it) and in exposed sites cover it with dry leaves or conifer branches. It starts into growth late in spring, only once the soil has warmed up for good. Most cultivars self-seed, 'Moudry' very freely, and the seedlings do not come true; if you do not want that, cut off the plumes before the seed ripens. In Hungary its first escape was described in 2020: along a road in Budapest it spread from planted clumps into pavement cracks and waste ground, and in Austria self-seeding has been observed in the warm, wine-growing regions. The EU invasive list does not include this species but its relative Pennisetum setaceum, which is sold here as an annual; it is not on the Hungarian, Slovak or Swiss lists either. The centre of an old clump thins out; divide it in spring when that happens.

Winter hardiness is borderline in Central Europe: in dry, free-draining soil it comes through fairly cold winters, but in heavy, waterlogged ground it often dies in a cold, wet winter. Do not cut it back in autumn, the dry foliage protects the crown; mulch it in exposed sites. It starts into growth late in spring, so do not dig it out too early. In good conditions a few seedlings may appear around it.