Ornamental grasses are popular in landscaping, valued for their texture, movement, and year-round visual appeal. While many of these plants are harmless additions to a garden, a select few species contain compounds that can pose a serious risk to humans and household pets. Understanding the difference between safe and poisonous varieties is an important step for home safety. This awareness is necessary in yards frequented by curious pets or small children who might chew on the foliage. Determining the identity of the grasses in your landscape is the first step toward creating a safer outdoor environment.
Identifying Common Toxic Ornamental Grasses
Certain ornamental grasses, including those from the Sorghum and Cordyline genera, contain toxins that can be harmful if ingested. Sorghum bicolor, often sold as ornamental broom corn, is a tall, annual grass featuring dense, reddish or black seed heads. Young Sorghum plants and new growth are especially concerning due to their high concentration of cyanogenic compounds. The Grass Palm, Cordyline australis, is a tree-like plant often used in containers or as an accent, identifiable by its long, narrow, arching leaves. It is known to be toxic to cats and dogs, as is Arrowgrass (Triglochin species), which is recognized by its rush-like, fleshy leaves typically found in moist areas.
How Poisonous Grasses Affect Humans and Pets
The toxicity of these grasses stems from specific secondary metabolites, such as cyanogenic glycosides and saponins. Cyanogenic glycosides, like dhurrin found in Sorghum species, are stored harmlessly until the tissue is chewed, which rapidly releases hydrogen cyanide (HCN), a highly potent toxin. Hydrogen cyanide is quickly absorbed and blocks the cellular ability to utilize oxygen, leading to rapid cellular death in tissues such as the brain and heart. Symptoms of acute cyanide poisoning in animals include rapid breathing, excessive salivation, muscle tremors, convulsions, and bright red mucous membranes. In contrast, the toxicity of the Grass Palm (Cordyline australis) comes from steroidal saponins, which irritate the digestive tract, causing vomiting, diarrhea, anorexia, and depression in pets.
Safe Removal and Disposal Procedures
Removing toxic ornamental grasses requires careful adherence to safety protocols to prevent accidental exposure, especially from dried or cut material. You must wear personal protective equipment (PPE) that includes long sleeves, pants, sturdy gloves, and most importantly, a dust mask or respirator to avoid inhaling fine particles. Toxic compounds like cyanogenic glycosides can be concentrated in the dried foliage, and dust from cutting can irritate the skin or be ingested.
Start the process by carefully cutting the grass stalks down to a manageable height, ideally about six to twelve inches above the soil line. A highly effective technique is to use heavy-duty twine or zip ties to bundle the entire clump tightly before cutting it, which minimizes the spread of loose, dry, and potentially toxic material. After the clump is cut, use a sharp shovel or spading fork to dig out the entire root ball, ensuring no toxic roots or rhizomes remain to regrow.
Disposal must be handled as hazardous plant waste, not standard green waste or compost, since the toxins can persist. The cut stalks and root ball should be immediately sealed inside two heavy-duty plastic bags, often referred to as double-bagging, to contain any remaining plant material or dust. Contact your local waste management facility to inquire about specific procedures for disposing of toxic plant matter. Never compost or leave toxic cuttings in open piles, as this poses a risk to wildlife and can contaminate future gardening soil.
Non-Toxic Ornamental Grass Substitutes
Gardeners seeking the movement and texture of ornamental grasses have many safe alternatives that pose no risk to pets or humans. Pennsylvania Sedge (Carex pennsylvanica) is an excellent option, offering fine texture and bright green color, growing well in partial shade. For a taller, upright visual element, consider Feather Reed Grass (Calamagrostis acutiflora), particularly the ‘Karl Foerster’ cultivar, which features striking vertical plumes. Prairie Dropseed (Sporobolus heterolepis) is a beautiful native alternative known for its fine-textured, mounding foliage and delicate plumes that smell like buttered popcorn when crushed. These options provide the desired aesthetic qualities without the health concerns associated with toxic varieties.