When and how to harvest worm castings is one of
the first questions aspiring worm farmers usually ask me when they
purchase a worm farm from me. This is not surprising because worm castings are surly one of the greatest benefits we can derive from worm composting. Being one of nature’s best organic fertilizers and soil conditioners many are keen to put worm castings into action in their gardens.
Many ways are leading to Rome and there are as well several ways you can harvest worm castings. Below I will show you the probably easiest way to harvest worm castings from a multiple tier worm farm.
No matter if you are working with a 3 tier or 5 tier worm farm, the process of separating the worm castings from the worms and the food is basically the same.
A fresh pile of worm castings.
If you have a Single worm bin please follow the link at the bottom of this page to our worm castingspage for harvesting
But lets get back to the “multiple tier worm bins"
A Midi Tower 3 tier worm farm.
A 3 tier worm bin starts off with the worms, bedding and food in the second
or middle bin.
A worm farm with food and worms in the middle bin.
The top bin will be empty and the bottom bin will be the place where the
excess liquid will be collected before it’s drained off.
3 tier worm farm with empty top bin!
Regularly add food to the middle bin of your worm
farm right on top of the worm bedding.
The worms will feed on the organic materials you add to the worm bin, digest
them and deposit them on top of their bedding as worm poop or worm castings.
A 3 tier worm farm with the top bin about half filled up.
Repeat this cycle till the middle bin will be full to the top. Then start adding food to the top bin.
Compost worms are top feeders and will always follow the food supply
upwards. So with time more and more worms will migrate into the top bin. You can assist this migration by always adding a handful of bedding and
worms from the middle bin to the top bin when you are adding food for the
When your top bin is more than half full most of your compost worms should have left the middle bin.
How to harvest worm castings
Now it will be time to harvest the worm castings from your middle bin. At this stage there should be no food left in the middle bin. To remove the remaining worms from the bin add a thin layer of food to it about 3 days before you want to harvest the castings.
On the day you want to harvest, remove the remaining food plus the top 5 cm / 2 inches of worm castings beneath the food from the middle bin. This way you will move the remaining worms from the middle bin and add them to the top worm bin.
The middle bin of 3 tier worm farm with worm castings.
The worm farm after the harvest of worm castings.
Now you can harvest the pure worm castings from your middle bin. Drop the bin that is holding the food and worms
to the middle of your 3 tier worm farm and place the
empty bin on top. Depending on the size of your worm bins and the amount of worms
they hold you should be able to harvest fresh worm castings every 6 to 8 month