Ornamental grasses care guide: when & how to prune, fertilize and spray
Miscanthus, Panicum, Pennisetum, Calamagrostis, etc. · USDA zones 4–9
Warm-season grasses look great all winter, then need a hard cut-back in late winter before new growth starts.
☀️ Sun
Full sun.
💧 Water
Low once established.
🪱 Soil
pH 5.5–7.5. Adaptable, well-drained. None. Rich soil makes them flop.
How and when to prune ornamental grasses
Cut back to the ground
When: 1–6 weeks before the last spring frost.
- zones 3–5: about Mar 29 – May 3
- zones 6–7: about Mar 4 – Apr 8
- zones 8–10: about Jan 14 – Feb 18
Removing last year's dead blades lets sun reach new shoots. Cutting after green shoots appear damages them.
- Tie the clump tightly with twine or a bungee cord around its middle. It turns into one tidy bundle.
- Cut the whole bundle off 4–6 in (10–15 cm) above the ground with hedge shears, an electric hedge trimmer or a pruning saw.
- Cool-season grasses (feather reed grass, blue fescue): just comb out dead blades and trim lightly. Don't cut them hard.
Tools: Twine or bungee cord, Hedge trimmer or shears, Gloves (blades are sharp)
Other care for ornamental grasses
Divide crowded clumps (every 3–4 years)
When: from 1 week before to 3 weeks after the last spring frost.
- zones 3–5: about May 3–31
- zones 6–7: about Apr 8 – May 6
- zones 8–10: about Feb 18 – Mar 18
Divide as growth starts if the center has died out.
- Only needed if the clump is crowded, flowering less, or dead in the center.
- Dig around the clump and lift it with a fork.
- Split it into fist-sized pieces with a sharp spade or knife, each with roots and shoots.
- Replant at the same depth, water well, and share the extras.
Tools: Spade, Garden fork
Common ornamental grasses problems and how to fix them
Dead center
Signs: Hollow ring with a dead middle.
What to do: Divide in spring and replant the healthy outer sections.
Ornamental grasses care FAQ
When should I prune ornamental grasses?
Cut back to the ground: 1–6 weeks before the last spring frost (around Mar 4 – Apr 8 in zones 6–7). Warm-season grasses look great all winter, then need a hard cut-back in late winter before new growth starts.
What soil does ornamental grasses need?
Adaptable, well-drained. Preferred pH 5.5–7.5. None. Rich soil makes them flop.
How much sun and water does ornamental grasses need?
Sun: Full sun. Water: Low once established.
What are common ornamental grasses problems?
Dead center: Hollow ring with a dead middle. Divide in spring and replant the healthy outer sections.
More perennials & grasses care guides
Timings are given relative to your average frost dates, with examples for typical US climates. Always read and follow product labels.