Answer: Rose trees require care similar to any rose: a full sun location with good air circulation, moist but well drained soil, and average or better fertility.
In the garden, you would fertilize with a general purpose granular or slow release fertilizer such as 10-10-10 in early spring and again in early summer per the label directions. Pruning would depend on which specific rose has been grafted onto the top of the tree.
Winter care will be difficult in your area because the winters are so cold and the graft must be protected from cold. If you plant it in the ground, in late fall after it goes dormant and before the ground is frozen, you will have to cut the roots on one side and bend the tree over to the ground, then bury it in a trench. Refill the trench and mulch heavily over top to try to insulate it from extreme cold.
If you keep it as a container plant you can bring the container into a cool location (above freezing but below 45 degrees) for the winter. Keep the soil just barely damp, not bone dry, while it is stored. In mid spring, take it back outside so it can wake up naturally with the season. As a container plant, fertilize with a slow release granular fertilizer or with a water soluble fertilizer with an analysis of 10-10-10 plus minors or similar.
Enjoy your tree rose!
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