How to Keep Landscape Grasses from Spreading

Two Methods:Controlling Running or Spreading GrassesKeeping Clumping Grasses from Spreading Too Much

Ornamental grasses are popular landscape additions because they have few pest problems and are easy to grow. They can provide textural contrast, screening and winter interest to the landscape. Most landscape grasses are clump-forming and will not spread to other areas although the clumps will get bigger each year. A few types of landscape grasses spread by rhizomes or stolons and some of these can become quite invasive, taking over the landscape. Here are some ways to keep landscape grasses from spreading.

Method 1
Controlling Running or Spreading Grasses

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    Confine the root system.
    • Cut the bottom out of a large plastic pot. Use heavy shears or a stout knife to cut the bottom out. The pot should be 12” (30.5 cm) or more across and at least 8” (20.3 cm) deep.
    • Bury the pot where you want the grass.
    • Center the grass in the pot. Use soil from the hole you dug to sink the pot to fill the pot.
    • Use a cement drain tile, metal culvert section or plastic drain tile without perforations buried in the ground to confine the grass roots if you don’t have a large plastic pot.
    • Set pots or other items confining roots into the soil so that you leave about 1” (2.5 cm) of the rim above ground.
    • Every few years you will need to lift the container and divide the grass plant to keep it from becoming root bound or breaking the container.
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    Plant the grass in a raised bed with walls or cement-surrounded bed. It will have the spreading confined to a certain area.
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    Use an air moat and mowing to confine the grass.
    • At the edge of the area where you wish to confine the grass dig a trench 6” (15.2 cm) across and 8” (20.3cm) deep. This air gap generally prevents rhizomes and stolons from crossing.
    • Mow the edge of moat frequently in case the grasses manage to cross it.

Method 2
Keeping Clumping Grasses from Spreading Too Much

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    Divide your clumps.
    • In early spring burn or cut off the dried grass leaves from the previous season if you did not do it in the fall.
    • Wait for new grass shoots to begin growing.
    • When the new shoots are still small dig around the whole clump of grass.
    • Spread a tarp or sheet of plastic on the ground.
    • Lift the clump of grass and place it on the tarp or plastic.
    • Using a pruning saw or a chain saw simply cut the grass root clump into chunks. You can quarter it or make more or less cuts depending on the size of the root system.
    • Replant what you want of the smaller root pieces and give the rest away.
    • Discard the center of the old root system if it has no new grass shoots growing from it. Some clumps die out in the center.
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    Use less fertilizer and water.
    • Grasses won’t grow as much if you skip the fertilizer and water only when it’s very dry.
    • If the plant’s growth yellows or looks spindly you may need to resume watering and fertilizer.


  • Running or spreading grasses spread by stolons underground or rhizomes above ground. Rhizomes and stolons are special stems, which spread out from the plant and from which new plants sprout.
  • New grasses are constantly being added to the ornamental plant list. Look them up to see if other gardeners consider them invasive before you buy them.
  • Clumping grasses spread by increasing the size of the clump or crown each year. Most ornamental grasses sold are clumping types because they are not invasive. But even clumping grasses can grow too large for the area they are in.
  • Running grasses and grass relatives include: Blue Lyme Grass, (Elymus arenarius), Japanese Blood Grass, (Imperata cylindrical), Ribbon Grass, (Phalaris arundinacea), Silver Banner Grass, (Miscanthus sacchariflorus), Lilyturf, (Liriope spicata), Mondo Grass, (Ophiopogon japonicus) and most types of bamboo. Japanese Forest Grass (Hakonechloa macra) will spread slowly but usually isn’t considered troublesome.
  • Offer to share baby grasses or divisions if someone will help you remove and divide them. It can be a big job to divide a large grass clump.
  • Choose ornamental grasses carefully, taking in account the mature size of the plant and whether it’s suitable for your site.


  • Whether you mind them spreading or not, non- native ornamental grasses should not be allowed to spread to natural areas. Some states have listed several ornamental grasses on the noxious or invasive plant list and you should avoid planting those grasses in your state.
  • Don’t plant large ornamental grasses up close to buildings. The dry foliage of grasses is extremely flammable. If you live where wildfires are possible large ornamental grasses should be used with great care and cut down and removed when they dry out.

Things You’ll Need

  • Containers 12” or more wide
  • Heavy duty shears
  • Pruning saw or chainsaw
  • Shovel

Article Info

Categories: Lawn Care