By bulbs I presume you mean rhizomes? If the rhizomes are dormant or almost dormant when you planted them then I would keep them in a cool place like the garage until you can plant them in the garden, which would be as soon as a the ground thaws. The rhizomes won't be hurt unless the entire pot of soil freezes, and that is unlikely in your garage now, in fact, soon you will want to move them outside at least by day to prevent them from getting too hot and sprouting too early.

If the plants are actively growing and above soil level then that's a problem and you basically have to grow them inside until hard freezes are over, then plant outside.

I grew them (both the white "grandiflorum" and the red "erectum") for many years in an Ottawa suburb when I was a kid. I had them in a small north-facing garden up against the house and they basically grew and multiplied and were happy. Their natural setting in Ontario is in hardwood forests, where they bloom before the leaves come out on the trees (so semi-shady), then leaf cover from the trees becomes quite dense by the end of May so they spend the summer in deep shade. The ground doesn't freeze very deep in trillium country so I would probably try to plant them in a north exposure up against a house so that the rhizomes don't freeze too hard in winter (or give them lots of snow or mulch cover). Definitely in shade.

Some pics I took of trilliums in the wild... Patch of Trillium grandiflorum:

Individual Trillium erectus (these don't often form patches, more like scattered plants:

Followup... Thanks for the tip, I headed to WalMart this morning and picked up 2 packs (8 rhizomes) of T. grandiflorum. They still look completely dormant so I'm just going to keep them in their original packs in the refridgerator to keep them dormant until the soil thaws and I can plant them directly in the garden. I have a good spot for them in the back garden -- it's very shaded by trees in summer but quite bright in the spring, and gets a solid leaf-cover mulch in the fall which I let rot into the soil over the summer. Here's hoping.

Thanks for the reply Don, since mine all started sprouting in the bag I'll have to bring them in the house until all frost has past. Hopefully, trilliums can thrive in a shaded part of the garden in the Canadian prairies.

I'll most likely plant mine under a sugar maple will the will benefit from the leaf litter produced in fall.

I planted mine outside today in a garden heavily shaded in the summer by some amur maples and an Ohio buckeye. I'll let the forecasted winter storm water them in :) Mine seem fully dormant (the roots look healthy and the rhizomes are plump but show no growth at all). I think the best I can hope for this year is that they put up a leaf sometime during the summer to build up energy for next year.

I was looking at Trillium bulbs here in Edmonton and it said Zone 4. I grew up in the Kapuskasing Ont area Zone 2 and the bush was full of them. Are these ones now hybridized and more tender?

I think the zones are really designed to reflect hardiness of trees and shrubs, so they indicate air temperatures and whether or not a tree/shrub and its buds will survive those temperatures. But for things like trilliums, winter air temperature isn't the most important thing, it is soil temperature that matters, ie whether the rhizomes will survive or freeze to death during the winter. Zone maps kind of break down for that purpose. Kapuskasing I believe (correct me if I'm wrong) has deep snow cover during the winter, which insulates the ground so much that the frost barely penetrates the ground. So from a soil perspective, or bulb hardiness perspective, winter soil temperatures in Kapuskasing are probably not much different than in southern Ontario in zone 6 or 7, where there is little insulating snow cover.

In Edmonton I'm hoping that by planting the crowns of the trillium rhizomes a bit deeper than recommended, plus adding lots of leaves for mulch (I planted mine in a woodsy garden) that might be enough to bring the plants through the winter successfully. I do have patches of daffodils in the same garden that have survived and multiplied over the 20 years since I first planted them.

I also bought some "erectum" but had to plant them up as they were activly growing in 2 days after I bought them. One has even flowered and is WHITE ug!! I have several of these growing wild in our wooded area and was hoping for the red. Maybe I'll go over to Walmart and try again only plant them into the ground. Lois

Refreshing this old thread...

How did folks trilliums fare this past year. Does anyone have a thriving patch on the prairies?

The 8 dormant rhizomes I planted in April were really slow to get started so I kind of gave up on them. Then I peaked behind some taller plants in early July and saw that at least two of them had put up leaves... just one leaf per plant though, and pretty tiny ones at that. A week or so later we had bad hail and everything got battered. So I'm not holding out much hope for them this spring, but I do have the spot marked and it's now melting out from under the snow, so we'll see.