How to harvest castings from a tote style bin

How to harvest your castings from a tote style bin


After you have fed your worm bin for 4 to 6 months (standard in a 10 to 20 gallon tote)  you will notice all this nice dark “soil” in the bottom.  This is the castings (worm poop) that the worms have created for you to use as their thanks for taking care of them.  You will want to harvest before the contents turn anaerobic (a wet stinky mess) on you.  If your bin is ready to harvest and the bottom is very wet line the sides of your tote with dry cardboard sheets, replace when wet, do this until the castings will form a nice loose ball when cupped.

*NOTE…this is for personal use only for the castings.  Retail sales involves a different method and/or equipment in harvesting.

I have used the following three methods in harvesting my tote bins before I changed over to using bigger beds and commercial type CFT’s (continuous flow through) bins.  Each one is dependent on how much time you want to spend harvesting the castings.

  1. Simple Transfer is to take the top third of your bin and place that in a newly prepared bin OR set this to the side to add back to the original bin after you have removed the castings. In doing this you will be adding back some of the beneficial microbes from your bin to help the worms adjust to the new bedding.


  1. Light Harvest Method involves placing the entire bins content on a flat surface under a light in a pile. Some do it as a cone or volcano shape to start with.  Scrape a layer off  until you see worms and then stop, the worms will dive down to escape the light.  Do this every 15 to 30 minutes until you have just a pile of worms.  DO NOT DO this in direct sunlight as the UV rays will harm/kill the microbes.  Indirect light works just as well or under a overhead light also.  *NOTE  The entire bin must be finished (no visible food or bedding particles) to do this unless you have a sifter to remove those particles first.


  1. Migration Method takes longer but is effective as well but you can’t use this method if your bin is a small tote OR is completely full. When the bin contents have been worked well and you can’t recognize any bedding or food pieces then push the entire contents into one end of the bin.  Add new bedding and food in the opposite corner and mix in a couple of handfuls of the finished section.  This process will take up to  3 weeks to complete.  If you want to make sure all the worms migrated over do the light harvest method on the remaining pile.