I had a Japanese Aralia planted under a tree that was killed by a lightning strike to the tree. Live in zone 9, do not recall how it handled our winters. How low a temp. will they tolerate? We had 1 of our rare winters last year when we had temps in the high 20s for several hours. Will they return after a freeze if cut back to the ground?
Japanese Aralia are hardy in zones 8-11.
20 to 30 degrees F is the range for temperatures.
A freeze to the ground may or may not also kill the roots. You can add a layer of mulch to help protect the plant.