Answer: Lilacs are very cold hardy and should do fine in your area when planted in the ground. Mulch over the root area with organic mulch. Place it in a flat layer about three inches thick over the root area. Do not push it up against the stems.
If your plant is still in a container above ground, I would suggest insulating the roots as best you can, either by sinking the pot into the ground up to its rim, or by heaping mulch over and around the pot (not overtop of the plant). Enjoy your lilac!
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