Guide to Watering your Worm Compost Bin: When, How Often, and How Much

Guide to Watering your Worm Compost Bin: When, How Often, and How Much

Water makes up around 70% of an earthworm's body weight, so having moist conditions in a worm bin is a critical element to their survival. That said, the rule of moderation applies to watering your bin. Similar to over-feeding, there is tendency to over-water worm bins when getting started. This can lead to factors that are not beneficial to your worm population, or conditions that can outright kill the worms. 

How to Water Your Worm Bin

Worms need a damp, but not wet, environment to thrive. Think about your yard or a local park, if you dig down a few inches the ground is usually moist but not dripping wet. That's the level of moistness you're after in your worm bin.  

We like simple rules at Brothers Worm Farm so here are a few to go by when watering your worm bin:

  • Rule #1: Moderation! You can always add more water. 
  • Rule #2: Never pour water into a bin. This will lead to over-watering or inconsistent moisture throughout the bin.
Tip #1: We've found a spray bottle or light mister works best to ensure the correct amount of moisture and an even distribution throughout the bin.
  • Rule #3: Target watering once per week. Watering daily or multiple times per week is not normally required. In many cases you can water every week or 2 - it depends on temperature, humidity, and other factors so monitor the bin and if you see it getting dry give it a good misting or spray.
  • Rule #4: Don't let water accumulate in the bottom of your bin. If water accumulates, gently dump it out or mop it up with paper towels. This is a sign you are watering too much so adjust your watering schedule and amounts!
  • Rule #5: Make sure the top inch or so of your bin is the most moist part of the bin. The bedding should get more dry as it goes to the bottom of the bin. Worms are attracted to water and will migrate to it in a worm bin. If water collects on the bottom many of the worms will find that attractive and migrate there, which is problematic since their food is placed in the top 1 inch of the bin.

Keep in mind that most of the food (e.g., fruits and vegetables) you feed compost worms will likely have high water content. This will help keep the feedings areas moist and those areas may not need as much water over time as other areas (e.g., the outer edges of the bin tend to get the driest over time). When watering I will often water the outer edges of my home bin more than the middle areas that remain moist from the high water content in my worm's food.

So, in sum, remember to moderate and not over-water your bin, keep the bottom areas drier than the top areas of the bin, and don't let water accumulate in the bottom of the bin. Your worms will thank you!

If you have any questions or comments, shoot us an email or check the other tips and how to articles on our blog. Happy farming!


Brothers Worm Farm

I’ve built a 4×10 x2’tall vegetable bed. I’d like to add worms to my soil. Would it be okay to add worms and how many would you recommend?

Thank you

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