Ornamental grasses, like many garden plants, are often susceptible to damage from salts in the air and soil. Grasses, generally less susceptible to salt damage than most garden plants, can still suffer if salt exposure is high or prolonged. An understanding of salt toxicity and plant selection goes a long way toward growing healthy ornamental grasses.
Salt damages plants in two major ways. The first is burning from foliar contact. The other source is salt toxicity in soil. When salt concentrations in soil are high, roots take up the salts, where they collect in leaf tissues, causing damage. Water intake from plants in saline soils is often poor, resulting in wilting and death.
Foliar damage happens when salt from sea air lands on grass blades, causing burning of tender leaf tissues. Excessive overhead watering with water-soluble fertilizers can lead to concentrations of fertilizer salts as water evaporates from plant leaves.
Saline uptake in roots occurs when salts concentrate in soils. Salts can accumulate with excessive fertilization or when tides or floods bring salty or brackish waters into the garden. Rising water tables can cause increases in salinity, as well. Accumulation of salt from ocean spray is a common culprit in seaside areas.
Foliar salt damage is evident by brown or black spots on grass blades. Saline soil toxicity causes leaf margins to turn brown. Often leaves turn yellow (chlorotic) with green veins. Yellowing progresses to brown, then black. Leaf drop and branch tip dieback often occur. A general reduction in plant vigor follows.
Plant salt-tolerant varieties of ornamental grasses for best results. Maiden grass (Miscanthus sinensis), growing 4 to 8 feet tall, is highly salt-tolerant. Muhlygrass (Muhlenbergia capillaris), bitter Panicum (Panicum amarum) and sand cordgrass (Spartina bakeri) also do well. For a show stopper, plant pampas grass (Cortaderia selloeana), which can grow over 8 feet tall. Dwarf pampas grass grows half as tall as its larger cousin.
In salt-prone gardens, plant ornamental grasses in well-drained soil. Sandy soils, in particular, readily leach salts out of the soil. Always fertilize according to plant needs and in compliance with label instructions to avoid unnecessary accumulation of fertilizer salts. When using liquid fertilizer, always water at ground level to avoid getting salts on grass blades. Collect rainwater, which is mineral-free, to use on saline-vulnerable plants.