Castings should only be harvested when the bin is full

Castings should only be removed when the hungry bin has become full to the top of the taper. Removing castings before the bin is full will affect how much food the bin can process. The hungry bin needs to be at least ¾ full of finished castings to work most efficiently. This is to ensure the finished castings in the lower part of the bin have been cured completely, and are fully compacted. When the floor is removed, the shape of the bin means only the castings in the bottom part of the bin will fall out. When the castings have been properly compacted and had enough time to consolidate, they are largely free of worms and clump together, making them easy to remove and handle.

If the floor is removed before the castings have become properly compacted, all the material present in the bin, including the worms, will fall out. 

How to harvest castings

  1. Remove the drip tray and pour any liquid there into a suitable container.
  2. Release the latches securing the floor to the lower body.
  3. Lower the floor from the bottom of the bin. The floor should be full of finished castings.
  4. Tip the floor upside down and tap sharply to knock out finished castings.
  5. If needed, clean the filter with a hose or some water.
  6. Replace the floor over the lower body and secure in place with the latches.

Some worms may be present in the castings. The worms can be easily separated from the castings by spreading them on the upturned lid, and placing it on top of the bin. The worms present will retreat from the light deeper into the castings and the top layer can be removed. The separated worms can then be tipped back into the bin.

Plants have evolved to uptake the nutrients created by worms – their castings are one of the most beneficial fertilisers for plants. Castings are pH neutral, so are very safe to use with all plants. Even a small amount of castings or liquid added to soil will improve the performance of plants.

They can be used in the same way you use compost, or heaped around plants. Pure castings may burn the roots of small plants if used undiluted. For use on smaller plants it may be necessary to mix the castings with other soil first.