Wetting Agents

Wetting agents are soap-like chemicals that weaken the surface tension of water, making it “wetter.” They are also called surfactants. They are available in either liquid or granular forms. The granular forms are made to be mixed with soil.

Wetting agents have several uses:

  • Add wetting agents to irrigation water to make the water penetrate hard-to-wet soils or potting mixes. For example, if peat moss dries out, it is very difficult to wet again. Some wetting agent in the water makes it wet easily. Wetting agent is also useful to penetrate lawns with thatch buildup.
  • A little wetting agent in the irrigation water, or added to a potting mix, ensures that all parts of a container get wet with one watering. Without it, it is possible for water to “channel” through a container’s soil without wetting portions of it.
  • Wetting agents are used to make sprays stick to waxy leaves better. In this use, it keeps water from beading on leaves. In the same way, wetting agents help sprays penetrate the waxy material on the outside of some insects, such as mealybugs.
  • Wetting agents help oil and water mix. Horticultural oil sprays include wetting agents to emulsify the oil, allowing it to remain in suspension in the water.