When is the best time to cut ornamental grasses

When spring growth is starting to get under way, ornamental grasses along with many other types of herbaceous plants, need to be cut back as it is best time to channel all their energy into new shoots from the base. But you need to be careful; don’t leave it beyond the end of April you may end up weakening the plants. Some ornamental grasses make dense clumps of stems and, after the winter, the old stems can insulate the base of the plants which encourages them to start into growth early.

Depending on how warm the conditions are, March and April are really your last chance to cut back the old stems, clearing the way for the new growth. But do check carefully for signs of new growth in amongst the old and try only to snip out the dead stems.

How far should I cut back ornamental grasses

Last year’s growth on grasses will be faded and brown in most cases. There are some grass relatives, mostly in the form of Carex species, which retain their green colouration through the winter, but these are best cut back too so that fresh growth can emerge.

Tracing the old growth down to the base of the plant, you should be able to use a pair of secateurs or garden snips to cut through the individual stems as close to the ground as you can. However, try to be careful not to cut new season’s green shoots. If you do accidentally snip a few off it shouldn’t matter if the majority remain intact. And as long as you don’t cut the new shoots right down to the ground, then they should be able to continue growing as all grasses grow from bands at intervals up the leaf blades. This is a natural adaptation to growth which allows most grasses to continue growing even if their tips are grazed by animals.

Should I water and feed ornamental grasses after cutting back

Thankfully most ornamental grasses are robust plants which, provided they are growing in a well lit place with sun for at least half the day, should grow well in all but the poorest, driest soils. Watering is beneficial for newly planted or freshly divided and replanted grasses during dry weather in the spring and early summer in their first season. But there after they should be able to source their own moisture.

It does pay to apply a mulch around the base of the plants after cutting them back. This mulch can take the form of well-rotted garden compost or bagged compost. Apply it in a layer3-5cm deep and in a circle, extending 20cm from the stems. This will help to enrich the soil, conserve moisture and repress weed growth giving the plants the best chance of remaining healthy during the growing season.

Fertilisers are not really necessary for ornamental grasses. In fact they will often grow too soft and can collapse and flop. Rich growing conditions can also leaves them vulnerable to disease and more liable to drying out in summer – something that is unlikely to happen without fertiliser.

What are the best ornamental grasses

Some of my favourite ornamental grasses are forms of Miscanthus, in particular the zebra grass Miscanthus sinsensis ‘Zebrinus’. There are many different varieties of this dense, clump forming grass genus which produces fountains of foliage which droops elegantly at the tip. In the autumn, elegant plumes of seedheads are produced which often last right through until late winter.

Also spectacular, is Stipa gigantea (the giant oat) which hass a relatively short clump of leaves with several tall, spectacular seedheads produced by late summer. This plant really does best in full sun.

For a position in partial shade, try Molinia caerulaea, or the purple moor grass. The variety ‘Moorhexe’ produces spectacular, finely divided seedhead in summer over elegant foliage. There are plenty of different ornamental grass species available and thorough research of varieties to suit your growing conditions and available space will pacy dividends.

For best results get new plants in the ground by the end of April.