How Much Surfactant Should I Add to a Gallon of Weed Spray?

Surfactants, also called spreader stickers and wetting agents, help herbicides, fungicides and pesticides spread evenly and stick firmly to plant leaves. Like soap, surfactants reduce surface tension and prevent liquid sprays from beading and rolling off waxy and furry plant surfaces. This increases their efficacy and reduces the need for multiple chemical applications. Recommended surfactant dosages for use with weed sprays vary from product to product, but dilution rates usually run about 1 to 3 tablespoons per gallon of herbicide.

Spreader sticker
Garden sprayer
Prepared, mixed herbicide or ready-to-use herbicide spray bottle
Measuring spoons

Instructions

- 1
  Measure 1 tablespoon surfactant, using a measuring spoon or the measured cap from the product bottle. Add the surfactant to a garden sprayer containing 1 gallon of weed killer.
- 2
  Replace the sprayer's lid and give it a quick shake to mix the contents. If you have a pump sprayer, engage the plunger several times to pressurize the sprayer.
- 3
  Spray the mix on a few target leaves to test the surfactant. If the liquid coats the leaves, you have added enough surfactant.
- 4
  Add another tablespoon of surfactant if the mix beads and rolls off the leaves. Repeat until the spray sticks to the leaves. Don't use more than the maximum amount recommended on the product label.

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