Caring for ornamental grasses

Ornamental grasses are fairly low maintenance, but there are a few steps a gardener can take to ensure that they flourish from year to year.

Many ornamental grasses need cutting back in late winter or early spring. In nature they would have either been grazed or had the old stems burned off in a prairie fire.

• Do not cut too close to the crown, 15 to 30 centimetres (six to 12 inches) is enough, and wear heavy-duty gloves, since the leaves can have serrated edges.
• Cut the cool-season grasses back in early spring and the warm-season grasses a few weeks later.
• Evergreen grasses and small-growing ones will not need cutting back at all, simply comb through them with your fingers to remove any dead stems.

• Mulch around the clumps in early spring, using garden compost or a commercial sterilized manure that is low in nitrogen, taking care not to cover the crowns.
• In regions with hot, dry summers watering will be necessary, but in most of the country the grasses will be able to survive on their own once established.
• Where watering is required, it is best to use a drip irrigation system that puts the water at each individual plant rather than overhead sprinklers that lose a lot of water by evaporation.

1. Once clumps get old, their centres die out and it is time to divide them. To achieve the best results, lift clumps in early spring, after cutting back the old stems, and cut them into pieces. You will find it necessary to use a sharp spade to cut through the larger clumps; however, a knife will be enough for smaller species.
2. Replant young material from the outside of the clump and discard the old middle. Running varieties are easy to propagate once they age. When you chop around the plant in fall and dig up the runners, pot a few and keep them watered while you dig up and throw away the old middle.

Properly positioned grasses growing in good soil seldom develop any serious pest or disease problems.

Signs and symptoms: Plants stunted, grayish insects in leaf bases.

Cause: Miscanthus mealybug.

Control: None known. Dig out and put in garbage. Inspect new plants carefully before planting.

Signs and symptoms: Reddish spots on leaves.

Cause: Rust.

Control: Plant far enough apart to allow good air circulation, spray with wettable sulphur.

Signs and symptoms: Plant collapses.

Cause: Crown rot.

Control: Do not plant too deep or cover crown with mulch.

Signs and symptoms: Plants eaten to ground level.

Cause: Deer, rabbits, or gophers. Usually only a problem on soft-leaved species.

Control: Protect with wire cage or fence.