Clematis Vine – should I nip off the spent blooms?
After the petals of the many blooms fell off, the finely spiked centers remain on the branches. Should I cut them off to encourage new blooms?
How and when to prune and deadhead clematis depends on the type of clematis you have. This article gives you general growing guidelines: https://www.gardeningknowhow.com/ornamental/vines/clematis/growing-clematis.htm
and this article goes into a little more detail: https://www.colostate.edu/Depts/CoopExt/4DMG/Flowers/Vines/prunclem.htm