The best time is spring while still dormant. However, if it is fairly large and well established you could cut the entire plant off at about 6-8" above the ground, dig it with as large an earthball as possible and get it into its new home immediately, watering it in well. It may not have a very showy bloom next year, but will probably live and re-establish. Spireas are pretty tough plants.

USDA 6 and warmer fall, right after leaf drop could be better.

where are you..

in my z5 MI ... when it loses its leaves in fall.. or as soon as the ground thaws in late winter..

fall is preferred because you have two cool seasons.. before the heat of the first summer ... time to grow some roots ...

ken

Thanks, everyone... I'm in zone 6, just outside of Philly. Sorry for not posting that before.

Ken, I've met you in the Hosta forum...

Fall might be the best time, then.

Thanks for your help.

I live in zone 4 and have a huge bridal wreath spirea (approx. 6ft.Hx4ft.W) that was planted too close to the neighbor's driveway but still on my property. How and when can it be moved when it is so large and will it die if it is moved? Also should a spirea be trimmed- when and how?

I have moved fifferent spireas at different times of year. Yes they are hardy but be prepared for them to look dead if you cut them back. They take a good season to push new growth.