Summary The harmful effect of de-icing salt on roadside herbs and grasses depends on the sensitivity of the plant species. Seedlings are more sensitive to salt than adult plants. At a low temperature (5aC) the plants were not affected by high salt concentrations. In winter with short frost periods (1-3 weeks) the harmful effect of de-icing salt on grasses and herbs will therefore be hampered by the low physiological activity of the plants.