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Green Tips: Maintaining and Harvesting a Worm Bin

Green Tips | June 4, 2020

If you haven’t seen our How to Set Up a Worm Bin tutorial yet, we hope you’ll check it out. Once you’ve set up your worm bin, it’s important to know how to manage and harvest it. Worm bins are low maintenance, but do require some work. By implementing the following management and troubleshooting tips, your bin will be on the right track in no time! Our tips will also help you harvest the nutrient dense castings from your worm bin to use on plants. 

A “Healthy” Worm Bin

Knowing what a healthy worm bin looks like is important. Monitor your worm bin regularly. Here are some characteristics of a healthy worm bin: 

  • It smells similar to garden soil or has no odor at all
  • No worms are trying to escape
  • Castings have accumulated
  • There is no exposed food
  • Mold and mites are on some food
  • Moisture can be found throughout the bin, but not excessive amounts
  • There is air space between the bedding in the bin
  • The worm population is steady or increasing

Troubleshooting Your Worm Bin

If your worm bin seems out of balance, it’s important to take action. Here are our tips for dealing with common worm bin issues:

  • Odor: If your worm bin smells foul, try to pinpoint the food item that is causing the smell and remove it. If the entire bin is odorous, immediately remove all food that has not sufficiently broken down. Add additional bedding throughout and on top of the food, leaving nothing exposed. 
  • Exposed food: Place a layer of bedding on top to cover all exposed food. 
  • Excess mites: Place a piece of bread in the bin, wait for mites to congregate on the bread, and then remove it. 
  • Excess moisture: This is a common issue with worm bins. Excess moisture accumulates when too much food is added to the bin. First, remove all food that has not sufficiently broken down. Second, place dry bedding in areas of the bin where liquid has accumulated. As a last resort, remove all bin contents and pour out the liquid, add bedding to the bottom of the bin, and return the contents. Air out your worm bin. Wait a day or two to add food. Do not overfeed the worms. 
  • Compact contents: Break up clumps of worms, food, and bedding and disperse it throughout the bin. Add bedding throughout to help aerate the bin. 

Harvesting your Worm Bin

Having a worm bin helps ease the burden on landfills. You can also harvest and use the nutrient-dense worm castings on your plants. With worms crawling around your bin, it can be a bit challenging to harvest the castings. Be sure to have a container ready to collect the castings and follow our tips to help you harvest:

  • Use the light: Worms are sensitive to light and will bury themselves when exposed. Try not feeding your worms 3-7 days before you plan to harvest so the worms decompose most of the food in the bin. Find a flat workspace and cover surfaces. Take out the contents of the worm bin and place it on your workplace (you may need to work with multiple piles of bin contents). As the worms bury themselves, take off the top layer of castings and put in your collection container. Continue removing the top layer this way until you reach a layer that has more worms than castings. 
  • Corral the worms: This process takes time and will reduce the amount of food you can place in your worm bin leading up to harvest. For 1-4 weeks (depending on the size of your worm population), only place food on one side of the worm bin. Over time, the worms will make their way to that side of the bin. Meanwhile, the other side of the bin can easily be harvested. Be sure to check for straggling worms when removing castings. 

We hope you find these tips helpful for managing and harvesting your worm bin. If you have any additional questions about this, please feel free to contact Lisa Darrigo, Program Coordinator at NYLCVEF at

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