Sunday, March 29, 2009

Emptying the bottom layer of your worm bin

In many of the discussions on worm bins people ask about either adding the next layer or how do they go about emptying the bottom layer (or even knowing when it's ready to empty).

I generally empty mine when the top layer is almost full (generally twice a year with my family) and I try and do it in the Spring and the Autumn i.e. while the weather is still reasonable.

A common misconception is that all the worms will have vacated the bottom layer and moved up. I've owned a wormery since 1998 and I have never yet known this to be the case - there are always a few of the stubborn ones quite happy in the bottom layer.

Emptying the bottom layer of the worm bin Emptying the bottom layer of the worm bin

So how do you separate them from the compost?

You have a few choices:

  • The first is don't bother. You can just empty the whole bottom layer in your border or compost bin where the few stragglers and eggs will either live in the garden, become live food for the birds or in the case of the compost bin carry on regardless. I like the last option because they can then colonise your compost and thereby speed up that process as well.

  • You can empty the whole lot into a barrow or onto a plastic sheet and hand pick them out, either adding them to your wormery again or even box them up and head off fishing. The choice is yours.

  • Put the bottom layer on the top with the lid off. Scrape away and remove compost until you come across some worms and then leave it for a bit. Worms hate the light and will burrow down into the compost that remains. Repeat this process until they have all burrowed into the layer below, by which time you will have harvested all the compost.
    Be warned though that this is a lengthy process.

When you remove the bottom layer you will almost definitely find that the sump is full of worms. Many beginners panic and worry about worms getting in the sump but they always do.

It's yet another reason to make sure you empty the sump regularly so that they don't drown.

They can and will climb out when they are ready but you're very lucky indeed if you never find any there.

Emptying the bottom layer of the worm bin Emptying the bottom layer of the worm bin

As you can see from the pictures both my bins have plenty of worms in the sump. So while we're emptying the bottom layer make sure you empty the contents of the sump (drain it of liquid first though) into the top layer. It tidies the sump up as well as helping establish worms in the new top layer.

So now you've emptied the bottom layer and cleaned out the sump you can place the now empty tray to the top of the bin.

When adding this new layer be careful to make sure that it fits snugly. If there's too much stuff in there then a) you'll be squashing them with the new one and b) they can get out of the sides.

I just add the layer and start adding waste - they will move up when they are ready i.e. they have eaten most of the layer below and fancy some of the new stuff.

I guess it wouldn't harm to take some of the bottom layer and add it to the new one, especially if it's quite full and stops the new layer fitting snugly. Definitely add the moisture mat (or a layer of cardboard) as the darkness will further attract them into the new layer.

Emptying the bottom layer of the worm bin

As you can see from the pictures, adding what's in the sump can make the wormery look quite wet and soggy so make sure you add a fair amount of shredded/scrunched paper and/or cardboard to help dry things out.

Emptying the bottom layer of the worm bin You can never have enough paper in a worm bin, something that people often forget. It helps keep things dry and adds a god dose of carbon. The worms will munch their way through it as fast (if not faster) than the food scraps and the resultant compost will be of a higher standard.


Nick Palmer said...

Just a point about wormeries. If you compost teabags then there will eventually build up a layer of plastic teabag "ghosts".

Teabags mostly have a percentage of polyester or pvc or polypropylene fibres in them so they can be heat sealed in manufacture (check it out on Wiki). I have never seen any green or composting site mention this so I find it my duty to tell as many as possible about this.

Take a look at a blog post I did on this a while back
worms and tea bags

Can you help to spread the word about this problem?

Soshanna said...

Great information and pictures. I have two wormeries, one like your can o worms and another solid one that has to be emptied top down. I much prefer the can o worms.

Thank you for sharing.

Janet Chadwick, Fertility Coach said...

What a great blog - I was inspired by Soshanna, and got a wormery a few years back, and also wondered about the worms in the sump (alas, i have sacrificed many worms to drowning!). Your advice was straightforward and incredibly simple to follow. I used to do the plastic sheet method, and I'm going to give the last one a try, now!

dynamind said...

There is another way to separate or "harvest" the worms: just put some sweet fruit pulp (e.g. rotten banana) on one spot and close the lid for a few days. The worms will gather at this fruity spot and can be collected easily (at least most of them - some stubborn ones will go their own way but for that one exile might be the best solution anyway).

Unknown said...

Great info! I have my first full tray now. Once I have cleared the worms, how strong is the worm compost - ie how much space can I spread one tray over? Thanks!