Answer: According to Michael Dirr's "Manual of Woody Landscape Plants" spireas are easy to root from cuttings with the best time frame being cuttings taken in June or July. They should be started in potting mix rather than water. Here are some instructions on how to take cuttings from shrubs. You may need to cut and paste the complete url into your browser to make it work correctly.
If you have ongoing access to the shrub, you might also consider layering. This method is much easier for the home gardener than babying cuttings.
Good luck with your project!
Q&A Library Searching Tips