Would like to lift plants, add rock wall and raise garden level with additional soil @ 6-7 inches. Best time?

Question

Hostas, toad lilies, astillbes and calla lillies

Answer 1

The best time to do this is during dormancy. These articles will help:

https://www.gardeningknowhow.com/.../calla.../growing-calla-lilies-and-care- of-calla-lilies.htm

https://www.gardeningknowhow.com/.../toad-lily/toad-lily-care.htm

https://www.gardeningknowhow.com/.../hosta/growing-hosta-plants.htm
https://www.gardeningknowhow.com/.../astilbe/growing-astilbe-plants.htm