Landscaping Tips - Ornamental Grasses

LANDSCAPING TIPS brought to you by the Arizona Landscape Contractors’ Association, the Sustainable Landscape Management (SLM) and the Arizona Certified Landscape Professional (ACLP) programs

Ornamental Grasses

Ornamental grasses fill an important niche in our southwestern plant palette. They are low-water use, provide welcome softness and unique colors and textures in contrast with other plant materials, while requiring only minimal maintenance to look their best.

  • Ornamental grasses are grasses, and should be treated as such. They may be low-water use, but they are not no-water use. Extra water in the summer helps these plants look their best year-round.
  • In general, ornamental grasses should be given more water than desert-adapted plants. This can be accomplished in several ways:
    • Hydrozone - if installing a new landscape, plan irrigation zones by grouping plants with similar water needs. Ornamental grasses perform best on their own zone, apart from trees, shrubs, cacti/succulents, and bedding plants, so you can water to their specific water requirements.
    • Emitter capacity/quantity - add emitters or size them up as needed. Often one emitter is placed at time of planting. As the grass matures and clumps, this may not be enough to wet the area where the roots grow.
  • Know your species and plant at the correct spacing and exposure. Clumping bunch grasses in general need plenty of sunlight and space to grow.
  • Grass clumps should be raked out several times during the year to remove dead leaves and trash.
  • Understand the blooming period of your grass variety so you don’t cut back the grass before it blooms and end up missing out on the beautiful blooms for the year.
  • Annual maintenance includes trimming the ornamental grass to promote vigor and maintain its appearance in the landscape without getting overgrown.
  • Grass clumps can be left alone until early spring, to provide live plant material during the winter months, when other plant varieties are undergoing hard cut-backs/rejuvenation pruning.
  • More commonly, ornamental grasses are cut-back during the winter months of December-February in the Phoenix area.
  • Clumping bunch grasses respond best to annual rejuvenation/hard cut-backs after they have been in the landscape for 2 or more years.
  • Grass clumps can be bundled with a bungee cord just below desired cutting height for ease of cutting and bundling trimmings.
  • Use sharp grass shears or power trimmers to cut grass to desired height.
  • Grass clumps can be cut just above the ground to minimize the accumulation of unwanted thatch. It will take a little longer to come back from this hard cut-back but the grass will thrive. Avoid leaving an unsightly clump of thatch.
  • If grasses are younger or it is desired to leave a green clump in the landscape, the trimming height can be adjusted.
  • After hard cut-backs, the ground is exposed – a great time to check emitters, and add new emitters if needed.
  • Don’t reduce water at time of cut-backs. The grass will be stressed and needs adequate water to recover.