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Planting and growing ornamental grasses in the garden

Ornamental grasses can fit into almost any garden theme. They add height, movement and long-season colour. Alongside the explosion of interest in these plants are the basic questions of growth, maintenance and care. Here are a few suggestions:

When to plant ornamental grasses

There are two planting windows for new ornamental grasses.

Spring: allowing plants to establish their roots before the summer heat and dry weather sets in.

Fall: 6-8 weeks before the first frost.

  • Plant grasses in clumps of at least three plants for maximum effect
  • Dig a hole 2 or 3 times the size of the root ball of each one.
  • Turn plants out and place in the hole with the crown just above ground level. Fill in with soil and tamp down.
  • Water sufficiently until roots are established.
  • Grasses require exceptional drainage. Generally not fussy about the type of soil, but check your plant's requirements before you purchase it.
  • Once established, many grasses are fairly drought-tolerant.
  • Water carefully. If your plant is a "prairie" grass it will be labeled drought-tolerant, which means very little water is required. "Woodland" grasses do well in moist soil.

Easy to maintain

Ornamental grasses are very easy to maintain. Set them up in the right conditions to begin with (sun or shade basically) and enjoy.

Here are a few suggestions for long-term care:

Cutting back

  • Tie the tops together in a bundle before trimming (easier to clean up!)
  • Trim back cool-season grasses in early spring. You want to enjoy their fall-interest beauty as long as possible! Leave approximately a third of the plant in place.
  • Warm-season grasses can be cut back in the fall.
  • Use a weed-eater for extensive coverage, pruning shears for small (or short) plants.

Dividing clumps

This is a technique to increase the number of plants...without buying them! Similar to dividing perennials, just harder for larger clumps.

  • Divide warm-season grasses in spring through mid-summer.
  • Divide cold-season grasses in spring or early fall
  • Use a large knife, trowel, or shovel to dig out and pull apart pie-slice wedges
  • Replant sections before roots dry out.
  • Wear gloves! Grasses may have sharp edges.


Most ornamental grasses trace their origins to native prairie or woodland plants. In the wild, they would rely on nutrients from their own decomposing foliage and that of the plants around them. Cultivated grasses are just the same. Therefor:

  • Mulch around your grasses with shredded leaves in the fall.
  • No additional fertilizing is required; in fact, for many grasses fertilizers are harmful.