Louise Curley

06 Mar 2024 15:13

Preparing Ornamental Grasses for Spring


Ornamental grasses have become a popular addition to borders over the last twenty to thirty thanks to the rise of the prairie-style, naturalistic planting advocated by designers such as Piet Oudolf and Cassian Schmidt. These grasses have many worthwhile attributes, adding texture and movement to borders, providing a long season of interest and being the perfect foils for herbaceous perennials.

Late summer and autumn are when most grasses are at their best, adding a golden glow to borders, but many of them continue to offer height, structure and interest right through to the following spring if they are left to stand rather than being cut back. Their feathery faded flower heads will capture the low light and dustings of frost and look magical.

Deciduous Grasses

This category of grasses includes: calamagrostis, panicum, molinia, miscanthus and deschampsia. Late winter or early spring is the time to give them a tidy up to prepare them for the new growing season. The buff-coloured top growth needs to be cut back to just above ground level to make room for the new leaves to emerge. You can use secateurs to do this, but for large clumps using a hedge trimmer or shears is quicker and easier.

Chop up the old foliage and either put it on the compost heap or lay it on the surface of the soil where it’ll act as a mulch. Birds will also help themselves to the prunings for nest-building.

Evergreen Grasses

This category of grasses includes: anemanthele, carex, festuca and Nassella tenuissima (also known as Stipa tenuissima). Early spring is a good time to give these a refresh. Unlike the deciduous grasses, they don’t need cutting back, instead comb or tease out any dead growth.

It’s advisable to wear gloves when doing this as the edges of some grasses can be quite sharp and they can cut your hands. Any growth that looks tired or is damaged but that won’t come out by pulling can be snipped back to the base of the plant. (anemanthele)

Dividing Grasses

Early spring is the best time to divide grasses. With big clumps I’ve found it to be too difficult to lift them from the ground – it isn’t good for my back! So instead I’ve taken to dividing them in situ by chopping off clumps around the edges, which means I can keep them to a more manageable size.

If you want more plants the small sections can be replanted elsewhere. For grasses in pots – this is how I grow anemanthele – I dig up the plant, placing it on a tarpaulin so that I don’t get soil everywhere, then I use a sharp spade to slice the plant in half.

If this doesn’t work because the roots are too congested an old pruning saw will do the job.

Annual Grasses

Grasses that flower and set seed then die all in one year are known as annuals. These grasses include: briza, hordeum and lagurus.

They are easy to grow from seed, and many of them make lovely cutting materials for flower arrangements and for drying to make wreaths and garlands.