Trimming and transplanting a bridal wreath

I need help from my Texas Gardening friends! I have two white Spirea (commonly known as bridal wreaths) that I want to trim and transplant. They simply need more room. Is fall the best time to trim and transplant or should I wait until after they have bloomed in the spring? I will be having the "dirt work" done for my butterfly and hummingbird garden done soon and I'm wondering about the timing to move these plants.

Thanks for your help.

If you trim and move your plants in the Fall you will lose some of the blooms bur it will be much kinder to your plants to move them when it is cool and they are dormant, that in the Spring when it is warm and they are trying to grow.