Where Is My Beautiful “Black Gold”?

Good question from Kristi:

My worm red wiggler compost is very wet and brown not black like I see on
videos. I feed mainly greens along with paper egg shells and coffee. Am I
doing something wrong? I’m composting indoors in Worm Factory 360.

Hi Kristi,

Many a new vermicomposter has wondered the exact same thing – believe you me!

The long and the short of it is that it comes down to the oxygenation/moisture balance in the system. The challenge with plastic bins – even stacking flow-through bins like the WF-360 – is that they are incredibly effective at keeping in moisture and reducing air flow. In some cases this can be very helpful – especially if you happen to be a neglectful worm steward (like me most of the time – lol) – but if you are a fairly active vermicomposter it can result in a less effective vermicomposting process.

It is important to remember that vermicomposting involves the aerobic breakdown/stabilization of wastes. Excellent air flow not only speeds up the process, but it helps to complete the stabilization (“humification”) of the waste materials – resulting in the beautiful, crumbly stuff you are craving. That being said, the color will actually depend on the starting materials – high quality castings are NOT necessarily going to be “black”.

In a typical plastic (non-draining) tub type of system, it’s not uncommon to see plenty of nice looking stuff closer to the top, yet down near the bottom you find something more like an off-color (often with a sewage smell to it) muddy material – or even layers of wet, completely unprocessed materials (likely stinking as well).
The lower half of the system is undergoing an anaerobic degradation process (tends to be much slower, and foul smelling) – while the upper layers, where the worms also tend to be more active, have enough oxygen for the stabilization process.

One mistake people sometimes make with stacking systems is to set up a bunch of trays at once. This is not recommend since it effectively eliminates the “flow-through” advantages of the system – and results in much slower processing in the lower trays. Assuming you ARE setting up one tray at a time (only adding the next one once the lowermost tray is consistently full), I recommend leaving the lid off for a few hours each day if possible. This should help to reduce excess moisture and increase aeration considerably.

Others reading this may want to consider using a completely open tub system (with a very thick layer of bedding up top instead of a lid), a well ventilated flow-through system like the “VermBin“, or a “breathable” system like the Worm Inn (just be careful not to neglect it for too long!).

Hope this helps!

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    • Ben
    • November 13, 2015

    Just a note on what colour good compost should be. Dr Elaine Ingham of
    Soil Food Web fame says that the colour should be dark brown not black.

    • rita
    • November 14, 2015

    If you have a 5 gallon bin, how many worms should you have? How often to you “harvest” the worms/compost? If the worms are procreating, as we assume they are, how and when might you divide them?

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