Yes, your spirea bush is Spierstrauch winterhart and one of the toughest flowering shrubs you can plant. Most varieties handle USDA zones 3 through 9 with no trouble at all. That covers a huge range of climates from bitter cold northern winters to warm southern heat.
I found out just how strong the Spierstrauch Winterhaerte is during a brutal winter three years ago. Temps dropped below -20°F (-29°C) for a full week in my zone 4 garden. I lost a young hydrangea and two roses that season. But every one of my spirea bushes came back strong in spring with fresh green growth and heavy blooms. That experience taught me to trust this shrub in cold climates above most others.
Your spirea survives cold through a smart natural process. As a leaf-dropping shrub, it sheds all its foliage in fall. This cuts water loss and protects the plant from freeze damage in the branches. The roots stay alive below the frost line where soil temps remain above freezing. All the stored energy goes into the root system during winter, ready to fuel new growth when spring arrives.
Use this Spierstrauch USDA Zonen guide to find the right match for your climate. Birchleaf spirea and Double Play Doozie handle the coldest zones down to -40°F (-40°C). Bridalwreath needs a bit more warmth and starts in zone 5. Check your USDA zone before you buy so you pick a variety that fits your local winter temps.
I tried one extra step that made a big difference for my youngest plants. In late fall, I spread a 3 to 4 inch (7 to 10 cm) layer of shredded bark mulch around the base of each bush. This shields the roots from bare frost when snow cover is thin. You should avoid piling mulch against the trunk though. Leave a small gap of about two inches so moisture doesn't rot the bark over winter.
You don't need to wrap or cover your spirea for winter in most zones. Just make sure you stop feeding it after August. Late fertilizer pushes soft new growth that freezes and dies back in the first hard frost. Let your bush go dormant on its own schedule and it will reward you with strong growth every spring.
Read the full article: Spirea Bush: Varieties, Care and Pruning
