Knowing the water content of fruits and vegetables can be a handy tool in helping us keep a reasonable moisture percentage in our worm composting bins.
As you likely know, a good moisture level in a worm bin is about 70%, or enough to yield a single drop of water if the compost is squeezed very firmly in your hand.
Use the handy reference numbers below to determine water content in fruits and vegetables.
Water Content of Common Vegetables
Iceberg Lettuce: 96%
Green Cabbage: 93%
Red Cabbage: 92%
Sweet Peppers: 92%
Green Peas: 79%
White Potato: 79%
Water Content of Common Fruits
*Data from Bowes and Church's Food Values, 1994
Why Do I Need to Know This Data?
One of the most common mistakes a new vermicomposter will make is to keep a worm bin that is way too wet.
This usually happens when people add food waste without additional bedding.
And as you can see, most fruit and vegetable waste are going to be much higher than the optimal 70% range which will keep your worm bins aerobic and your harvests easier and more worm-free.
So this means you need frequent additions of drier, carbon-rich bedding to soak up all of that excess moisture that you're introducing to your bins. This will help control mites and fruit flies as well.
While I don't suggest that you try to calculate your food waste and bedding moisture levels down to the “gnat's rear-end” levels, I think it's incredibly helpful to know what's actually going into your worm bin.