Yes.. frozen! The freeze will still maintain a majority of the beneficial microbes, but it will also kill off any insects. I try to harvest out as many of the active cocoons and hatchling earthworms, but any missed ones will perish in the freeze. They do get a chance.. for a little while anyways. Harvesting takes me quite awhile and the sorted vermicompost goes into plastic storage containers a bit bigger than a shoe box. The containers then get put in a plastic bag and frozen for 2 weeks before I plan to use them.
I start a lot of plants in early spring and the vermicompost I find gives my transplants a nice boost. I dilute it with captured water and the vermicompost tea is offered to the young seedlings. When they get larger and get repotted, the vermicompost is mixed into the soil mix. As well I use vermicompost tea to presoak old seeds or varieties that are known to have low germination rates. (The nutrients, especially nitrogen and giberellins, in vermicompost help break seed dormancy and provide a boost to the seed's energy reserves that may be otherwise too depleted for the seed to sprout.)
I use a closed bin for my worms that has holes poked around the sides for ventilation. Although this particular design is not the most efficient for harvesting, it does allow me to set up the bins and not have to deal with them very much at all until spring. I keep the gang in the garage where they won't freeze, but it does get quite cold.
This is how I set up the bin for winter..
- 1st layer consists of heavier stems, stalks, twigs
- dried vegetation (bean pods, iris leaf trimmings, seedless weed trimmings.. somewhat larger fibrous plant material)
- a few scoops of vermicompost
- spent potting soil (end of the season nutrient poor soil in containers get put in.. no diseased plants)
- few more scoops of vermicompost (by scoops I mean enough to cover the layer by 1 to 2 inches as this will innoculate the other material with microbes)
- food scraps
- few scoops of vermicompost
- topped with straw/ shredded newspaper or a mix
By spreading vermicompost between the layers the material gets innoculated with the microbes the worms are accustomed to and also helps in preventing the bin from hot composting. To keep it from heating up is why I have it layered this way with the "browns" at the bottom and the "greens" at the top. The last layer is to control moisture as well provide a more protected area for the worms to feed under, yet fluffy enough to offer good air exchange.
By the time I am done the bin is already more than 1/2 way filled. I keep an eye on the contents for the next several days to make sure they do not heat up. I have never had a bin start hot composting when I layer it like this. The heat and gasses from the contents hot composting will wipe out the worm population, so you want to avoid it.
This isn't the only way to set up an enclosed bin.. just one of the ways I do so that by January/ February I have some bins finishing up in time to harvest.
You want to avoid putting diseased materials in the vermicompost bin. While some pathogens like e. coli and salmonella don't survive in an earthworm's gut.. some plant diseases like verticillium wilt and fusarium wilt DO survive.
Ever cut into a potato and see black spots just under the skin in the white area? That could be fusarium wilt. Best to avoid it as much as possible, and learn how to identify it. These 2 in particular can live in the soil for many year.. as well many plants can be their host.