When fast growing sages (and other plants) get old, the work needed to run its vascular system is harder, and they often die . Also, the root system has pretty much used up the best nutrients and has been decomposing, raising the titer of pathogenic micro flora and fauna.

A plant is considered a perennial if it lasts five years. The best way to keep one plant going is to root cuttings or divide the crown every 2 - 3 years. It's a lesson I've learned many times with my collection.

Sometimes the 2 - 3 year old plants make it better through the winter, especially if the replacement cutting was rooted late in the season and had too few roots for its pot.

My Lady in Red self-seeds like crazy. I have them throughout my garden. They take over the joint if I don't thin them out. every year.

~Annie