Does Salt Kill Buckthorn?

Salt and Subterfuge

• Even with highly salt-tolerant plants, such as buckthorn, too much salt can lead to plant damage and eventual death. Injury often remains hidden, especially during winter dormancy. Damage originates through leaves, but more extensive damage occurs when soluble salts move through the soil and accumulate in the plant's root zone. This can happen quickly or over years. As salt levels rise, water is drawn out from plant roots toward salt concentrations in the soil. Unable to draw up water and vital nutrients, the dehydrated plant undergoes drought, even with high soil moisture. Buckthorn may do well in heavily affected areas, but you should watch out for signs of distress on the plants.

Effects and Evidence

• Depending on variety, buckthorn hardiness stretches from U.S. Department of Agriculture plant hardiness zone 2 through 9. When salt accumulates on buckthorn leaves though, cold hardiness diminishes. Exposure to salt sprays can lead to cold damage at temperatures the plant could normally withstand. Similarly, while drought-tolerant plants tend to be salt-tolerant, high soil salts lessen a plant's ability to handle drought. Increased watering becomes necessary. Leaves and growing tips appear brown and burnt, growth slows, nutritional deficiencies become apparent and unnatural growth formations occur. Seedlings and young plants are most susceptible. In extreme situations, even mature buckthorn can succumb.

Prevention and Intervention

• A vigilant eye and preventive care help buckthorn succeed, even in salt-heavy locations. Take preventive steps to avoid salt buildup in the soil. Ensure good drainage at planting time. This encourages salty water to move through soil rather than accumulate around roots. Mulch the soil surface to limit evaporation. This keeps salty water from being drawn to the surface and settling around buckthorn roots. Avoid all unnecessary fertilizers, which add salt. If shoveling roadside snow, don't pile it where runoff will impact plants. Leach the soil by slowly providing several inches of water to dissolve and move salts away from the plant as you reclaim affected soil.

Consideration and Concern

• Widely cultivated for ornamental value and salt tolerance, buckthorn offers resilience and beauty. Unfortunately, birds and other wildlife feed on the attractive fruits and disperse seeds where buckthorn should not grow. The plant can be highly invasive in certain environments and smother native wildflowers and shrubs. Nurseries rarely offer common buckthorn (Rhamnus cathartica), which grows in USDA zones 3 through 8, because of this concern. Alder buckthorn (Rhamnus frangula), which grows in USDA zones 2 through 7, can also be invasive, but several cultivars exist that do not bear viable seed. Italian buckthorn (Rhamnus alaternus) and coffeeberry (Rhamnus californica), both of which grow in USDA zones 7 through 9, offer several non-invasive, salt-tolerant alternatives.