How to Treat a Wood Worm Bin

Earthworms require that their wooden worm bin be treated without harsh chemicals.

Wooden worm bins are subject to continual exposure to dampness. They contain bedding ideally kept at between 70 and 80 percent moisture, as well as seepage from food scraps and the mucus-laden excrement of the compost worms. While it may seem advantageous to waterproof the worm-bin interior to prevent wood rot, most hobbyists look for safe ways to preserve the wood from premature failure without exposing either compost worms or the resulting worm compost to chemicals harmful to plants.

Things You'll Need

• Latex primer
• Latex finish coat
• Drill, 1/2-inch bit
• Hardware cloth
• Marine spar varnish

Instructions

1. Select or construct a wooden worm bin made of hemlock or redwood for durability or untreated pine for minimal expense. Avoid any type of treated lumber in your worm bin, according to the Seattle Public Utilities website. Do not use black walnut or cedar, which contain tannins that may distress the worms.

2. Treat the exterior of your worm bin. Paint it with good-quality latex primer and a latex finish coat.

3. Drill ½-inch drainage holes covered with hardware cloth or screen in the bottom of your bin to remove excess moisture.

4. Apply two coats of marine spar varnish to the interior of the worm bin, allowing each to dry for 24 hours or longer in humid conditions. Introduce a test population of worms to the varnished worm bin for several weeks to note if they flourish in proximity to the varnish before adding your entire worm population.

Tips & Warnings

• Dry out your worm bin annually by taking it out of service for several days for longer life. Keep your worms, their bedding and food in a Rubbermaid tote or trash can during the drying time.

References

• Red Worm Composting: My New Stacking Worm Bin
• WormPost Northeast: Worm Bin Setup
• Wood Worm Farms: FAQ

Resources

• Seattle Public Utilities: Tilth Worm Composting Bin
• Vermontworms.com: Red Wiggler Compost Worm Bin