Salt Tolerant Plants

Salts are a necessary and common element of soil. Yet soil salinity - the measure of the total amount of soluble salt in the soil - can often be a death sentence to plants at relatively high levels. Soluble salts can cause harm to plants if they are in high enough concentration in water or soil. This effect is mainly indirect by pulling moisture out of roots and reducing the uptake of water and nutrients to affected plants. Some salts can be toxic to root tissue - usually causing serious disfigurement or death. Tip and edge burn of leaves, slow growth, nutrient deficiencies, wilting and eventual death of the plant can occur if the salt level is excessive for the plant and the problem is not corrected.

Though variables exist within species making classification of aerial salt tolerance a relative judgment, the following list of trees, shrubs and perennials consists of specimens time tested for tolerance. Use this list as a guide to select plants with the greatest tolerance to the inevitable (yet necessary to enable public access in winter) salt and pollutants that accumulate on our CNY roadsides and exposed areas such as parking lot perimeters.

Symptoms specific to evergreens:

1. needle browning moderate to extreme, beginning at the tip;
2. needle browning and twig dieback on the side facing the road but none or very little on the back side;
3. no needle browning or dieback in branches near the ground under continuous snow cover;
4. needle browning and twig dieback less severe further from the road; 5. browning usually first evident in late February or early March and becoming more extensive through spring and summer.

Symptoms specific to deciduous plants:

1. leaf buds on the terminal part of branches facing the road very slow to open or do not open;
2. new growth arises from the basal section of branches facing the road, resulting in a tufted appearance;
3. flower buds on the side facing the road do not open but flowering normal on back side.

Choose plants rated as 'intermediate' where salts are present at minimums or low levels - areas such as parking lot and sidewalk perimeters and low traffic roads - and choose 'tolerant' species where salts may be in concentrated levels as found along busy roads (and ocean breeze). Avoid using plants rated 'sensitive' in areas of possible salt contamination - restrict the use of such plants to areas further within the landscape where they will not be exposed to - and therefore harmed by - roadside contaminants.

          Salt-affected plants are usually stunted with dark green leaves which, in some cases, are thicker and more succulent than normal. In woody species, high soil salinity may lead to leaf burn and defoliation. Grasses also appear dark green and stunted with leaf burn symptoms. Symptoms of salt spray damage:

General injury patterns:

1. injury more severe on side facing the road, plants one-sided due to branch dieback;
2. damage more pronounced on downwind side of highway;
3. plants further from road injured less;
4. branches covered by snow not injured;
5. injury to evergreens apparent in late winter, injury to deciduous plants not evident until spring;
6. branches above the spray-drift zone not injured or injured less;
7. damage increased with the volume and speed of traffic and the amount of salt applied to highway;
8. plants damaged over several years lack vigor and soon begin to die;
9. less winter-hardy plants injured more severely;
10. salt spray penetrates only a short distance into dense plants; plants in sheltered locations lack injury symptoms

For your reference, We have prepared a list of plants. The file is in pdf format and requires Acrobat Reader.