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Easy Ways to Rat-Proof Your Compost Bin

A common misconception and one we are often asked about is whether composting will attract rats.  Rats are quite prevalent in San Diego, particularly roof (or tree) rats.  Palm tree and other dense vegetation (bougainvillea, honeysuckle) provide ideal habitats. Food is often supplied from fruit trees, vegetable gardens, and bird feeders. Compost bins are not typically a preferred rat habitat, and by always covering composting food waste, a food source is denied. One of our educators has been a San Diego residential composter for almost 2 decades and only twice encountered rats. Both times it was because food had been left exposed.

However, if you want further assurance, unwanted critters can easily be avoided through the use of the rat-resistant tips outlined here and proper storage of feedstocks (compost ingredients). Basically, you want to deny habitat, security, and food for rats.

For composting projects in areas where rodent activity is high—the use of fully enclosed bin systems may be your best option. If using an open pile, it is especially important to fully cover, or cap, any active compost piles with a biolayer: at least 2 inches of finished compost, at least 6 inches of unscreened compost, or 12 inches of wood chips, to avoid attracting rodents.

Deny Habitat

  • Enclosure – fully enclosed bins, particularly tumblers.
  • Raise bin off ground (for burrowers).
  • Place bin on a concrete or sand base.
  • Hardware cloth – use to place under bin and/or line bin.
  • Reduce clutter.
  • Properly store feedstock and/or garbage.
  • Rats are attracted to prior rodent infestation, using urine as an attractant. You may need to power wash hard surfaces to remove signs of rat activity.

Deny Security

  • Rats don’t like open spaces. Keep compost bins away from a fixed wall or fence.
  • Don’t create harborage (safe shelter). Dense vegetation often provides rat habitat.
  • Rats only need a space the size of a quarter to gain access. Find and seal all external holes in garages and sheds to keep rodents from getting in. Use rodent-proof materials: ¼ inch 18-22 gauge wire hardware cloth.

Deny Food

  • Avoid composting meats and oils.
  • Bury fresh food waste 6 inches deep (open pile system).
  • Cover with finished compost (open pile system).
  • Properly store feedstock and/or garbage. Don’t leave birdseed and pet food out at night.
  • If your yard has fruit trees, nuts or vegetable gardens, make sure you pick food as it ripens. Don’t leave fallen fruit or vegetables lying on the ground.
  • Encourage predators (owls, hawks).

The use of poisonous bait is never recommended because it can endanger the lives of pets and other wildlife. The use of glue traps is just plain cruel.

For more info or questions specific to your property, call our rotline at (760) 436-7986 ex. 700.