Q. What are some signs of salt damage in outdoor plants?
The coastal gardener's greatest challenge is salt damage. Plants are vulnerable in several ways, such as through root absorption and salt spray on the foliage. As salt-sensitive root hairs absorb water from soil, excess salts eventually destroy their cells. While salt accumulations challenge roots, salt spray damages foliage, producing symptoms of scorching or burning. Dune plants are the most salt-tolerant. Beyond 1/8 mile from the sea, salt tolerance becomes far less of an issue.
Landowners who live along streets that have been heavily salted for snow and ice are also familiar with the problems of salt damage. Salt used to clear ice and snow from roads and sidewalks is also a problem for city trees. In the city, it is important to flush out street tree pits at the end of the winter. One solution is to place mulch in the tree pit before the onset of winter. The mulch will absorb much of the salt and can be scraped off and thrown away in March or April. Remember when mulching not to pile the mulch up against the base of the tree trunk. Too much mulch may cause the trunk to rot and encourage pests and diseases.
Salt is toxic to plants. Once absorbed into a plant, it can reduce hardiness and subject the plant to greater winter damage. In the soil, salt will absorb moisture and restrict water that is available to plants. Plants may look drought-stricken even when adequate moisture is available. The chloride and sodium molecules that make up salt are also individually dangerous to plants; chloride accumulates in the leaves to dangerous levels and announces itself as leaf scorch.
For more information on the challenges of coastal gardening, please refer to our Coastal Gardening Guide.
For information specific to tree care in the city, please refer to our Street Trees Guide.
Courtesy of NYBG Plant Information Service