How many inches will vanhouttei spirea grow in one year?

Question:vanhouttei bridal wreath &shirobana spirea

Answers:
While vanhouttei is a more rapid grower than other cultivars (like anthony waterer), much will depend on cultural practices, ie, amount of light, water, fertilizer, soil type, protection from insects and leaf spots, etc.

They can get 8ft with a similar spread.