Breeding Earthworms for composting and gardening
All adults should know about the MANY benefits of having earthworms inhabit garden dirt. And adults have an obligation to children, to ensure that children learn about those benefits - so they will continue the practice of making gardens habitable for earthworms.
This section is about earthworms that will populate garden dirt and raise their families there - providing their many benefits to make each successive garden season even better.
There are earthworms that will do that - and earthworms that will not. There are 'manure' worms (red wigglers for instance) who do not do well in garden dirt with less than a 5% organic matter content. They do very well in a pile of manure, and do OK in a compost pile - but do not fare well in a garden dirt with low organic content, and do not survive in the average 'flower bed'. That earthworm is called Eisenia Fotida.
A cousin, the Europena Nightcrawler (Eisenia Hortensis), does not do very well in a fresh manure pile, but does OK in a compost pile, and lives/reproduces quite well in organic garden soil with an organic matter content of 5% or better and will tolerate the average amended 'flower bed' with an organic level of 2%.
While the European Nightcrawler makes a good fishing worm, the best fishing worm (in my opinion) is the Canadian or African Nightcrawler. As you can guess, both of these earthworms prefer either a cold climate or warm climate.
But neither of them make a very good garden worm.
So if it's a garden worm you seek, do your research based on the climate you live in, and choose the best earthworm for your particular needs.
While ROI company raises red wigglers for their composting compatriots, the main emphasis is on Eisenia Hortensis, the European Nightcrawler, because it is approved for import by the EPA, and because it is an "all-around" worm that performs well in a stable compost pile, in garden dirt and in the 'average' flower bed too.
What does an earthworm eat? Whatever goes into its mouth. Earthworms are predators, not composters. Yes, I know - raising earthworms is called vermicomposting by the earthworm breeding industry. Remember that composting is a human management activity. Managing earthworm breeding is not managing the temperature, air content and microbial community of the earthworm bedding that earthworms eat to poop their castings.
But, I'm not going to quibble the point. Composting is a process managing the reproduction of microbial communities to decompose organic material into organic matter, then humus. Yes, microbiology is at work in the bedding, but managing that community is not the focus of breedng earthworms.
Earthworms don't compost any more than horses or cows or sheep do, that eat vegetation and poop what's left. That's all earthworms do too, except they eat only rotting vegetation, not actual green stuff. Oh well - whatever...
So I'm not going to get picky about what some people call the practice - because it's a good practice. A rose by any other name is still a rose.
Point is that earthworms are VERY good for gardening, and if you have earthworms in your garden, you know that. If you don't have earthworms in profusion - you should. Your garden will grow MUCH better with earthworms in abundance. They aerate and provide channels for water percolation. Their castings (poop) is in a form that microbes QUICKLY turn into plant food, and the process already started in the earthworm's gut via the digestive bacteria in it.
There are two basic theories about the best way to raise earthworms for gardening.
One theory says to buy earthworm stock and just stick 'em in the dirt and let them fend for themselves.
The other theory says to raise earthworms in a controlled environment, harvesting their eggs (capsules or cocoons) for propagation, and placing the over-stock of mature worms where you want them to propagate.
So really, the question is: should you breed the earthworms, or just add them to the ground where you want them to grow - and forget them?
The answer is quite simple. You cannot know or control how the earthworm community is breeding in the ground. You can in a contained environment.
So certainly there comes a time when the mature earthworms should be harvested and put to good use in a finished compost pile or garden bed/row. So do you just get a big glob of earthworms in their castings and stick that in the ground? You can, but at that point the castings are no longer a good source of food for the earthworms - they have processed the bedding into mostly poop.
If done right, the earthworm bedding has been through the gut of earthworms at least once and preferably twice. So when they are placed in the ground, a food supply of stable or finished compost should be placed in the ground first, then the earthworms into the new bedding, covered and watered-in. Then most of the earthworms will 'stay put' and breed - that's the whole point - providing an environment in the ground for earthworms to breed there.
If a garden or flower bed is properly amended and/or mulched with organic material, the worms will have a steady supply of food. With sufficient water the earthworm population should double every couple of months.