I have a large patch of established trillium and they self seed like crazy. I have found the seedlings have shallow roots and are actually quite easy to transplant despite their reputation. They definitely prefer rich soil and dry shade.

Trillium seedlings develop slowly and they look different each of the first three years. The first year seedlings have two linear leaves and that is it. They go dormant about July in my climate and I think a lot of people mistakenly think they have have killed them when they do that because the adult plants don't die back that early. The second year seedlings have one heart-shaped leaf that also dies back in July. The third year seedling has the tripartite leaf and may or may not flower. The fourth (or fifth) year plants look just like the third year plants, but they will generally flower. They don't die back until October or November, when the full-size adult plants also go dormant.

Since you ask about encouraging it, you could try a very dilute solution of an acid plant food. I did that one year and my trilliums got huge. Be careful not to over do it. I would use about a 25% solution and I would not apply it more than once.

I don't leave much leaf litter. I clean up most of the leaves in the fall, but I do mulch a lot with compost in fall and spring if I have the time.

Your west coast trilliums do not do well in the east and vice versa. I would suggest starting out with your western trilliums.

Last November I bought 4 Trillium grandiflorum on sale, $3 each. They just looked like pots of dirt. They overwintered in their pots sunk in the ground. I planted them this Spring and 3 of the 4 are coming up.

According to your description, Karchita, it looks like I got Trilliums of different ages. 3 are up and 1 is a no show, but maybe I broke off the shoot on that one accidentally while transplanting, it happened to be the tiniest shoot.

Here are pics, how old do you think these are?

Trillium 1 - looks like it's going to flower

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Trillium 2 -
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Trillium 3 -
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I've never seen a T. grandiflora with spotted leaves but there are other trillium varieties with multi-colored leaves. There are pix of the various trillium varieties at the site below for you to browse. Enjoy!

FataMorgana

Here is a link that might be useful: Trillium key

The photos are of a Trillium with sessile flowers(base of flower attached directly to stem of plant) and is not T. grandiflorum, which has pedicillate flowers(flowers held above the leaves by a separate stem(peduncle). The flower color of those shown, will be purple or maroon, apparently.
Likely is one of the commonly available Eastern species, T. sessile or T. cuneatum(often sold as T. sessile). Most of the other purple/maroon-flowered sessile Trilliums, with patterned leaves, are rarely available.
The mottling on the leaves of T. sessile will begin to fade out as the plant ages during the season, the mottling remains on T cuneatum.
Once the flower opens and the plant reaches maturity, if you wish, you can key the features and identify the species.
Rb

How interesting! Thanks for the info. All four pots appeared the same, with a tag that says "Trillium grandiflorum Large white Trillium" native New England Perennials, Nursery propogated. I guess they mixed up the Trilliums.

The shoots on the 3rd and 4th ones looked different. There are probably 2 different kinds of Trilliums. Maybe they are T gradiflorum, but I can't tell yet, #3 has tried to leaf out but the tiny leaves are wilty (we've been having really dry hot weather for April).