That is just beautiful. I've been trying to grow it from seed for several years with no luck. Worth the extra effort!

As a lover of oleander, I'm strongly tempted to grow this one. Sort of like a hardy oleander! Lovely stuff.

Janet's Garden

Beautiful blooms! Your plant looks very happy & healthy. I planted mine in dry shade and it sadly passed on to plant heaven. : ( They like lots of moisture.

Jen

Congratulation!
You have a lot of courage to plant it in your z4 and you won!
Take it from Connecticut's kalmias lover, where they grow like a weeds.
Here are few pictures of another kalmias you might want to consider in a future,

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Keepsake

Despite the popular belief that kalmias are shade lovers (they are shade tolerant, that's it) kalmias if planted in a too shady location will not bloom as good as those that are planted in part to full sun. The main trick is to give them protection from the WINTER sun to avoid dissecation of the leaves. In their young years they need to be protected (as you did) from the cold AND from the sun, but later on, winter sun will be your worse enemy. Use wilt-pruff and/or burlap wrap/screen.
Water well before ground will be frozen, but do not overwater in a summer (especially if planted in a shade), cause Phytophora ramorum fungus while being harmless to overall plant's health could seriously ruin aesthetic appearance of the leaves.

Good luck!
Now I'm convinced that I could grow camellias!

How tall do they get?

In answer to the question how tall they get - about the same as a lilac. We've had one in our backyard for about 30 years, and it's about 10 feet tall. They grow wild in the woods around here, and I'm sure some of them are taller than ours. But I'm sure they could be pruned back. Ours is just the wild variety, not a named cultivar.

Right, 10'+.
However, Kalmias are very slow growing plants, 3-4"/year is the most you should expect from established plant.
They are naturaly leggy and in most cases if left to their own become a bare 6-7' tall trunks plus 3' of greenery on a very top. In this case only pruning to the stab (complete rejuvenation) is the remedy. They respond well to such treatment (the same way as rhodies) and produce a lot of new growth from the base.
Judicial pruning at young age is recommended to prevent legginess, but in this case you may end up with only 2" of growth per year.

Thanks! They look like such a great addition to a shady spot.

there are dwarf varieties also now.