Earth worms generally move less then 5 meters of 16 feet in the soil a year. The local population of worms is extremely important in the soil food web.
Increasing the population of worms will help keep the nutrient cycle turning in your garden helping with the soil health and as a result increasing plant health and yields!
Providing a good home for worms will allow them to increase their populations in the garden while turning organic material into wonderful vermicompost.
Making the winter pile is fairly simple to do. Simply add layers of organic material such as used coffee grounds, garden waste, comfrey, brewing waste and a little extra potting soil if you have it. It is important to add to the pile slowly so you don’t create a hot compost which will drive the worms away. It is preferable to have a nitrogen heavy pile as most worm varieties require nitrogen rich food.
You will want to stay away from diseased plants with powdery mildew or blight as this can help prevent the spread of these issue in the future. Adding things that have hardy seeds like tomatoes can also be an issue. With the cold nature of the compost it is not enough to deactivate the seeds and they may volunteer in inconvenient places.
Thin layers of each feed stock will help keep the pile from matting down preventing much needed oxygen for the worms and to help the pile insulated from the harsh winter temperatures. Leaving snow piled on top will again help keep the pile insulated from the harshest winter temperatures as snow and the air it traps is one of the best insulators out there.
This pile is unlikely to stay warm throughout the winter and will freeze solid. That is not a problem earth worms are used to that. The pile should attract this years earth worms resulting in them laying cocoons that keep clusters of eggs warm. In the spring the worms will hatch or return to the pile and continue to increase their population with the help of new material being added.
Some worms will burrow deep in the ground below the freezing line and over winter. In the spring returning to the surface once it warms up.
Allowing the worms time in the fall before freeze up to colonize and lay eggs in the pile definitely helps. Although we have received our first frost of the year it will be 8-10 weeks before the ground begins to freeze.
If you have a little more space and live in higher growing zones you can create a compost pile large enough to stay warm throughout the winter and keep the adults working and alive.
Overwintering Earth Worms