Plants tolerant of rock salt – a common ice melt used in winter
Winter brings snow, ice and slush; thus messy and slippery walkways and roads. To melt this mess, and allow safe walking and transportation, most cities, towns, and residents apply rock salt (sodium chloride) to these surfaces.
This form of rock salt becomes lethal to plants. As it melts snow and ice and dissolves into the resulting liquid, the salt makes its way into the soil, and its sodium and chloride ions separate. The sodium ions replace the phosphorous and potassium needed by the plants. The chloride ions when absorbed by the plant roots, travel up to the leaves, build up to toxic levels, interfere with photosynthesis and cause cell damage and leaf scorch. Salt also absorbs moisture from plant roots, causing a drying out or desiccation of the roots. Plants affected by rock salt may show signs of drought even when the soil is wet or waterlogged. And too much salt could result in the pooling of water on the soil surface. FYI: Earthworms and microorganisms are adversely affected by rock salt as well.
Some highly salt tolerant perennials include Dianthus, Wood Aster, Goldenrod, and low Day Lilies such as ‘Happy Returns’. Groundcovers such as Bearberry or Barren strawberry and grasses such as Little Bluestem or Maiden Grass are also quite salt tolerant. Perennials that are somewhat salt tolerant include Creeping Phlox, Heuchera; Coral Bells, Bellflowers, Yarrow, and some Sedums including Sedum ‘Autumn Joy’ and Hens and Chicks. Hosta, Purple Coneflower, Thyme and Daffodils have the least toleration for salt.
One way to prevent salt damage is to stop using de-icing salts and use coarse sand. The sand provides traction and makes the paving less slick. Or use the organic ‘Ice Melt’ de-icing product made from magnesium chloride. You can also protect your evergreen plants and shrubs from the salt by wrapping burlap around them or putting up fence barriers.