The lack of foliage by this time of year would suggest failure. Varietal hardiness shouldn't have been a factor, at least not in the conditions you describe.

Probably a combination of issues that have done it in.

My thoughts...18"-24" of growth sounds excessive for a 1st year magnolia unless it had access to a lot of fertilizer (either time-release in container or subsequent application). The nutrient rich growing conditions may have delayed dormancy and/or affected its minimum temperature tolerance (dormant plants require time to develop maximum seasonal hardiness).

Thanks for the reply,smivies. I suppose there may have been an excess of fertilizer in the container, but it certainly wasn't obvious. No additional fertilizer was used at any time over the summer. As for delayed dormancy, it certainly did not seem that way. 'Daybreak' did not retain its foliage late in the fall; it was completely in synch with other plants.

The only other thing I can think of is wind. On a number of occassions this past winter, we had unusually high winds combined with sub-freezing - but not sub-zero - temperatures. I realize magnolias are thin barked and can lose excessive moisture that way. Other magnolias - seiboldii, 'Riki", stellata, for example show no signs of wind or any other kind of damage even though they were equally exposed. Only difference is length of time in the ground.

I suspect some plants are not as winter hardy their first year after transplant. I have this Nyssa sylvatica for example.

Also I have noticed the young volunteers of many species I have keep their foliage longer than the adults.

Maybe a combination of these two?

'I suspect some plants are not as winter hardy their first year after transplant.' I have found that to be the case too. I haven't 'lost' whole trees, but have had severe winter damage and die-back on them the first winters in.