Why Does Salt Kill Grass?

Both the seaside and the desert create hostile environments for grass. What these two environments have in common is soil that contains salt. Salt or other forms of sodium are common ingredients in homemade grass killers. This is because sodium has an ill effect on many plants.

Although your landscape may not be near the ocean or a desert, it can still suffer from salt buildup. Salt is a common ingredient in products used to melt ice in driveways and on roadsides. Cheaper ice melt products may have salts in the form of calcium chloride or sodium chloride. These products can drain onto your lawn in winter. Lawns that have salt problems may appear dead near roadsides or driveways.

In the days before refrigeration, one of the most common means of preserving food was to dry it, often by storing it in salt. Salt was such an important commodity in food preservation that salt made up a portion of Roman soldiers’ pay. This is where the term salary comes from. The same action of salt that was such a boon in food storage is a detriment to grass.

All cells have a permeable membrane through which water can pass. This process is called osmosis. When salt is present in the soil, plants absorb the salt along with water and transport it to all portions of the plant's system. Salt is a salute, which means it draws water to it. The water in the saline solution is drawn from the cells of the plant through the cell walls to the saline solution.

Not all grass is affected the same by salt. Turf varieties such as Kentucky bluegrass will often succumb to lower saline content in soil. Cool season grasses such as ryegrass, fescue, wheatgrass and alkaligrass will resist lower saline levels better than bluegrass. In warmer climates, St. Augustine grass will grow in saline soils. Because of this, St. Augustine grass is often planted in areas near seashores.