Answer: Alpine bells, Cortusa matthioli, is a hardy, summer-flowering mountain plant that favors wet rocks and moist glades. This primrose relative requires cool, moist, humus-rich soils. Arrowhead Alpines (ph# 517-223-3581) carries the plant, and they may be able to help you decide if the plant is appropriate for your region--especially with respect to cold hardiness AND tolerance to summer heat.
There are many bulbs hardy to zone 3, including some varieties of crocus, daffodil, tulip, allium, and snowdrops, among others.
You might be better off planting marginally hardy plants, such as the lobelia you mention, in the spring, so the plant will have a full summer to get established before facing the harsh winter. However, if you can provide good winter protection this first season, you might be fine. (A deep snow cover is a great insulator and protector!) Because asters flower in the fall, I would be inclined to wait until spring to plant, but, again, if you can provide some protection this first winter you may be fine. I suggest you contact Burpee's Customer Service department directly at email@example.com to discuss their shipping schedule.
Peonies are quite particular in that they must be planted at the proper depth--the buds on the crown should sit about 2" below the soil surface. Planted deeper or shallower than that, and they suffer.
Hope this helps!
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