Pruning Japanese Blood Grass
When and how — Imperata cylindrica 'Red Baron'
Prune your japanese Blood Grass in March — the optimal month is usually March.
The next pruning window is March next year.
When to prune?
The ornamental grass japanese Blood Grass is pruned in March.
Cut ornamental grasses once a year, at exactly the right moment.
Ornamental grasses split into two groups with very different needs. Warm-season grasses (Miscanthus, Panicum, Pennisetum) die back above ground over winter and are cut down to about a fist's height in February or March. Those dry stems provide winter interest and protect the crown from frost and rain. Cool-season grasses (Stipa, Carex, Festuca, Deschampsia) stay green or semi-evergreen and must NOT be cut back hard — a spring tidy where you comb out the old dead blades with gloved hands is enough. Hard-prune a Stipa and whole tufts can rot out and die.
How to prune japanese Blood Grass
Japanese blood grass requires minimal pruning, but an annual tidy-up in March keeps it looking sharp and encourages fresh, vibrant growth. By late winter the previous season's foliage will have faded to straw-coloured or brown, and cutting it back makes way for the new red-tipped blades that emerge in spring. Use a pair of sharp garden shears or secateurs to cut the entire clump down to about 5–10 cm above ground level. Work through the clump systematically, gathering handfuls of old stems and slicing through them cleanly. The foliage is fairly soft compared to some ornamental grasses, so the job is straightforward. Rake up and compost the trimmings, or bin them if they show any signs of disease. Timing matters: prune too early in winter and you remove the structure and subtle winter interest the dried foliage provides; leave it too late into April and you risk damaging emerging new shoots. March offers the sweet spot when the worst frosts have passed but new growth is only just beginning. Japanese blood grass doesn't need deadheading because it rarely flowers in our climate—its appeal lies entirely in the foliage. If any flower spikes do appear, you can remove them, though they're uncommon. Throughout the growing season, simply pull away any dead or damaged leaves by hand to keep the clump tidy. This grass doesn't require shaping or thinning; the annual spring cut-back is all the pruning it needs to perform well year after year.
Common mistakes
✗ Cutting warm-season grasses down in October
You lose the winter silhouette AND the crown drowns without the protective dry stems. Wait until late February or early March, just before new growth starts.
✗ Hard-cutting cool-season grasses
Species like Stipa tenuissima and Festuca tolerate it poorly and may rot out. Combing with gloves is the right approach.
Too late this year? Here's what to do
Better to wait than prune at the wrong moment. The next optimal window is March next year. Until then: leave the plant alone — only remove dead or diseased wood (which you can do year-round).
