Why Does Salty Soil Kill Plants?

Salt Steals Moisture

• If you apply salt directly to a plant, the salt will draw water out of the plant's roots and leaves. This theft takes place via a process called osmosis, where water molecules travel from areas of high concentration to areas of low concentration. Just like all living things, plants need a lot of water to stay alive. If salt sucks too much water out of a plant, the plant will eventually die.

Salt Dries Soil

• Salt doesn't necessarily need to be poured directly onto a plant to kill it; even salty soil can kill plants. When soil is full of salt, it saps moisture so plants cannot drink. When a plant doesn't get enough water, it cannot convert sunlight into energy via photosynthesis. If you plant something in extremely salty soil, your plant may die before it even begins to look dry.

Salt Can Affect Soil pH

• Your soil may be acidic, neutral or alkaline. Most plants grow best in neutral or slightly acidic soil. If you live in an urban area, salt can turn your soil alkaline and cause concrete in sidewalks, driveways, and buildings to break down and integrate into the soil. This broken-down concrete will raise the pH of your soil and could kill your plants.

Salt Kills Invertebrates

• You know you can't put salt on an earthworm, slug or snail. In fact, some gardeners may recommend lightly salting your yard to get rid of invertebrate pests. Not all invertebrates are bad for your plants, though; they add water, air and nutrients to the soil. Your plants thrive on organically rich material that invertebrates leave behind in the form of castings.