Let's see if I can help.

First, there are 3 types of worms. I don't remember the scientific names, but I'll call them composters, borrowers and horizontal burrowers. Composters don't live in dirt. They live above the dirt in the organic matter that falls to the ground. If there are a lot of worms in a garden, either there is a thick layer of organic mulch in the garden, or the worms are not composting worms.

Worms will die if the temps drop much below freezing. Worms can survive in an outdoor worm bin if care is taken to insulate the bin and possibly provide a heat source by feeding heavily with high-nitrogen foods.

I would say that the gentleman you spoke to prior to starting was right. The speaker at the garden club either

1) Has a very thick layer of organic mulch on her garden, and/or

2) is seeing different worms than her composting worms in the spring or

3) The composting worms are laying eggs before they die and it is the offspring that she sees in the garden.

Hi All; The answer is!

Directly copied from excerp from Dr Clive Edwards Book Soil Biology ,Soil Biology Primer Chapter (8) Earthworms.

Surface soil and litter species  Epigeic species. These species live in or near surface plant litter. They are typically small and are adapted to the highly variable moisture and temperature conditions at the soil surface. The worms found in compost piles are epigeic and are unlikely to survive in the low organic matter environment of soil.

Upper soil species  Endogeic species. Some species move and live in the upper soil strata and feed primarily on soil and associated organic matter (geophages). They do not have permanent burrows, and their temporary channels become filled with cast material as they move through the soil, progressively passing it through their intestines.

Deep-burrowing species  Anecic species. These earthworms, which are typified by the "night crawler," Lumbricus terrestris, inhabit more or less permanent burrow systems that may extend several meters into the soil. They feed mainly on surface litter that they pull into their burrows. They may leave plugs, organic matter, or cast (excreted soil and mineral particles) blocking the mouth of their burrows.

Sbryce nailed it on the head with number three. Eisenia Fetida will thrive in Michigan in a good layer of organic matter. One reason they are sometimes favored over others for composting is that they propagate so prolifically in comparison. Well, there is a good chance their breeding rate is to facilitate survival of the species. . . or rather they have survived because of their breeding rate. Whichever evolutionary school of thought you adhere to. Either way, their short lifespan due to sensitivity to cold is compensated for by heavy breeding. The cocoons will survive the winter. The worms will survive the summer heat if you provide them what they need.

If you have a regular compost bin or windrow the worms will find you. I live in central Indiana and dug my first round of wigglers from a manure spread at a wood line. The manure wasn't purposely inoculated. I also have them in my regular compost bins outside. They dwell at the edges when the compost is hot and they tend to dig in to it well when it cools or when winter hits. Again, I don't inoculate it with worms. In other words, I am not raising those worms on purpose. My raised garden beds have wigglers. I did inoculate those, though, and do so every time I add castings.

As I say when teaching about raised beds: The goal is not to have a raised garden bed. The goal is to have a worm bin you can plant things in. Keep the worms fed with plenty of good compost and maintain good moisture so they will stick around. Insulate them in winter with leaves so they survive a little longer to break some leaves down. Their offspring will take over where they left off in spring. Of course, if you add cocoons in spring from an indoor compost bin, you will have a much higher number of worms for the summer months. I've read, though I haven't verified, that worms don't adapt well when moved from an indoor bin to an outdoor bed. That's including worm farms that have experimented with moving worms to outdoor, in ground worm beds. It's supposedly best to just get the worms to breed in propagating bins and spread cocoons when you spread the castings.

I have raised the Eisenia fotida (composting worm)for going on six years now for commercial resale purposes.
I question sincerely whether my composting red wiggler would survive on a large scale, the soil in Michigan.
If massive amounts of organic materials was piled onto the area in the fall, however, then this area would have red wigglers in the spring of the year-having survived the harsh winters of Michigan.
Red wigglers need over one foot of organic material piled up in order to go down and escape the freezing of the top material. If the freeze goes over one foot deep with just one foot of organic matter, the worm will freeze to death, as they can't bury themselves in hard soil. If they can't bury themselves, they will freeze to death.
I keep my commercial stock of red wigglers in an unheated barn, and they survive just fine through Wisconsin's harsh winters. I cover the aged horse manure with hay and straw for insulation-which is why they survive. The worms go "semi" dormant-meaning they feed very little and little if any reproduction occurs in the winter time. My worms require a little soil in the organic matter, to provide the 'grit' necessary to digest their food.

In general my though is if you have an indoor bin spreading worms in the garden is a waste of money If you keep some mulch in your garden and lots of compost it will be full of worms the free way

Also the frost line can change very much from on location to another on my 40 acres there are places that are low ground I can scrape the snow off and dig a hole no problem other spots have 5 feet of hard frost

Don't worry I will take the million dollars in payments of worms..

"red worms can live 4.5 years in a bin, but only 1 year in the wild" I can believe this. Nature and excess dryness and excess wetness probably does them in.

"bulk up her landscape" if she means raise the level of her gardens or lawn then I think in a few years what would be gained is eighths of an inch not inches. Even yards tall of leaves and grass over 10 years melt down to a few inchs. The grass is better in the tiny area where my old heavily composted garden was.

Worms have been found crawing around buckets of ice and leaves mixed.

I wonder if the garden lady buys new worms each spring and only vermicomposts during the summer. It would seem to reason that once the carrying capacity of a garden is met for worms that adding worms will only temporarily increase their numbers until naure rebalances them. If I had a ton of worms that were outgrowing every container I would maybe put some in a garden waste pile. Sharing them would be better. But if garden club lady is happy putting them in the garden I can't see as how it is hurting anything. Maybe she just does not want a bin inside the house over the winter.

I agree with the previous posters.