Why Does My Clematis Bloom Earlier than My Neighbor's?

I have a very large clematis. It seems to bloom earlier than all my neighbors' plants. Is this because I do not prune it back for the winter?

Bloom times can vary due to the variety of clematis grown as well as the growing conditions and care it receives. Your clematis may be a different species or variety than your neighbors' plants. Different species and cultivars of clematis bloom at different times during the growing season. The same type of clematis may bloom a little earlier or later depending on the temperature and light at that particular site. Dormant season pruning helps control the plant's size but can sometimes delay flowering.