Everyone likes an upgrade. Whether it's a faster car or a more efficient cell phone, it's hard to turn down a better version of something you already like. Plants are much the same. If you already love that gorgeous catmint that flowers all season long, what not try one that not only has all the same great attributes but also has an improved habit. Today we're talking about plants we have a great affinity for, but that plant breeders have made just that much better. Perhaps it's a longer bloom time, or stronger winter hardiness, or even a different color to the foliage. Whatever the change may be, it's an improvement that has made us fall even more in love with these classic plants.

Expert testimony: Irvin Etienne is Curator of Herbaceous Plants and Seasonal Garden Design for The Garden at Newfields in Indianapolis.