Liquid compost drains naturally from your vermicomposting worm farm through the drainage holes in the bottom of the bin. In a healthy worm farm, the amount that drains is limited to the amount of excess water that is generated by the actions of the worms. This fertilizer is often referred to as worm tea. It is a very rich fertilizer and is also effective for suppressing plant diseases.
By mixing worm castings with water, you can produce a liquid fertilizer. Leave the mix to stand for up to 12 hours, stirring occasionally.
Worm castings are ready for harvesting when there is very little food or bedding material left in the mix. There are several methods of collecting the castings.
Split the Bin
If you do not want to empty the bin, you can divide the contents by moving all the castings to one side. Place new bedding and food in the space you have created. Leave the bin to sit for 2 or 3 days. The worms will migrate across to the side of the bin with the new bedding and food in it.
At this point, you can scoop up the worm castings and the contents of the bin teased across to fill the space. Continue to operate the farm as usual. Very few worms will be trapped in the castings. If you are going to use the compost straight away, you can pick the worms out or leave them to help in the garden.
Split the Bin (2)
If you don’t want to wait a few days, you can remove the castings from the bin and spread them on a large piece of polythene. Pick out the worms and return them to the worm farm. You can also remove some of the worm cocoons. These contain the baby worms. Use the compost or store it in plastic bags until needed.
Empty the Bin
Place a large sheet of polythene on the ground and simply tip out the contents of the worm farm. Do this on a bright day or under bright lights. The worms will burrow into the compost to escape the light. Gently brush the compost off the worms and they will burrow deeper. Keep gently brushing the compost off the worms until you have a pile of worms and a pile of compost. Move the worms into another prepared worm farm. Use the compost or store it in plastic bags until it is needed.
Move to a Second Bin
Prepare a second worm farm with fresh bedding and food and place it on top of the worm farm to be harvested. Over a few days, the worms will migrate from the farm that contains only compost to the more attractive fresh food and bedding. All you have to do then is empty the bin.