How to Spray RM18

How To Spray RM18

RM18 is a signature product from Ragan & Massey designed specifically for lawn replacements, garden bed prep, and clearing weeds from walkways, buildings, and roadsides. Its unique combination of two herbicides kills weeds and plants while leaving fertile soil untouched, making it ideal for lawn and landscape projects you can’t wait to tackle.

Like our other popular weed killer, RM43, RM18 contains Glyphosate, isopropylamine salt, just less of a percentage than RM43.

RM18 is a great choice for a fast-acting weed and grass killer, but you want to take steps to make sure it’s applied correctly for it to be most effective. Just remember, RM18 kills weeds, plants and grasses on contact and won’t wash off once dried, so make sure you’re only spraying the vegetation you want to kill.


  1. Get the right dilution ratio. The proper ratio will depend on your weed control goals. RM18 has a slight variance of 3 to 6 fluid ounces per gallon of water. For larger, more mature weeds, use the 6 ounces per gallon ratio, while small seedlings only require the 3-ounce dilution ratio.
  2. Mix it up. RM18 can be used in both a tank sprayer and a hose-end sprayer, depending on the size of the area you wish to cover. For tank sprayers, always use one that is made of plastic, fiberglass, stainless steel, or is plastic-lined. Never use a galvanized or unlined steel container. Spot treat or spray evenly over 300 square feet. For hose-end sprayers, consider using the Ortho Dial ’n Spray with the dial set to 4 to 6 fluid ounces. Add 4 to 6 ounces of RM18 or 8 to 12 tablespoons for each 300 square feet. DO NOT add water. Spray evenly. After spraying, any unused product can be poured back into its original container.
  3. How to spray. There are a couple of tips that will help you really knock it out of the park when it comes to killing unwanted weeds and plants with RM18. First, spray the weeds or grasses you want to kill until thoroughly wet. Also, when spot-treating weeds around desirable plants, shield plants from drift with a piece of cardboard or plastic. If by chance some desirable plants are accidentally sprayed, rinse them off immediately with water or cut off the treated area.


A couple extra things.

Here are just a couple of extra points you should be aware of when using RM18:

  • For best results, apply during warm, sunny weather (above 60-degrees) to accelerate systemic movement from foliage to roots.
  • Apply on a calm day to prevent drift to desirable plants.
  • RM18 is rainfast in 30 minutes – meaning it won’t wash off after that time.
  • Don’t apply RM18 in a way that may come in contact with a person or pet, either directly or by drift, while your spraying – keep the kids and pets inside until 30 minutes after you’re done.
  • Do not apply through any irrigation system.
  • Don’t use as a spot treatment in lawns (RM18 kills grasses) or after planting any fruits or vegetables.


Make the most of your time, money, and effort with these spraying tips and get it right the first time.

Need more information about how to apply RM18? Read the RM18 product information guide here.