Answer: I think you are referring to the "Endless Summer" hydrangea. This is a variety of Hydrangea macrophylla that is special in its winter hardiness and its ability to bloom on both old and new wood. It is considered hardy into zone 4 which is where your zip code places you.
For best results, plant in a spot that is sheltered from the winter wind. Select a spot in sun all morning or very bright dappled light all day long. The soil should be rich, organic and humusy. For blue flowers the soil pH should be at least slightly acidic. Also, the soil must be evenly moist yet well drained, meaning damp like a wrung out sponge, not sopping wet/saturated and not dried out. During the growing season, maintain a layer of organic mulch about three inches thick over the root area.
In the late fall after the plant is dormant, mulch heavily over the root area. For added winter protection, in late fall you may also want to put a wire mesh cylinder around it, stuff that with dry nonpacking straw or oak leaves, cover the top with a tarp to keep it dry, but leave a gap for air circulation; remove gradually in the spring as the weather settles.
Enjoy your hydrangeas!
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