Four or five years for leaf retention would be exceptionally long. Three years or so would probably be closer to average. A very few hybridizers have emphasized leaf retention in their efforts, but attractive flowers, ease of growth, hardiness, etc. have been the more usual aims so little attention has been paid to the length of time individual leaves last.

The best you can do is to make sure the soil is suitable for rhododendrons, plant correctly, mulch, water when needed, protect from winter sun and wind in the first 2-3 years. Some varieties can keep leaf coverage all the way to the ground for their entire lives . Others do become bare at the base even when treated perfectly. The best solution to this is planting naturally lower and slower growing varieties to screen the bare trunks.

Easy/foolproof? Some very definitely are. Others much less so. A good local nursery probably carries varieties well suited to your area. The so-called Iron Clad types as well as the many hybrids developed by David Leach are excellent places to start.

Thank you so much! So in short, if I see a very old rhodo 8+ feet tall, with all it's healthy leaves in their glory top to bottom, it's most likely an iron-clad species?

Also, after I wrote this post and I went out for a walk, I realized that a lot of the really lanky ones I used to think looked awful are actually more like trees, with a 4 or 5' trunk with a sparse canopy.

Without any specific information about your location it's hard to tell, but an 8 foot tall rhododendron in Z6 could well be one of the Ironclads. It does not have to be, though. More importantly, full leaf coverage from top to bottom is also strongly influenced by light exposure - something I should have mentioned in the first post.

Any rhododendron which receives sun from one direction only will grow strongly toward that source of light. If the only sun comes from overhead, it will have a much greater tendency toward lanky upward growth and bare trunks than if it received low angled morning and afternoon sun in addition to or instead of exclusively overhead sun.

The ironclad hybrids are largely based on the native American species r. catawbiense. From it they inherited hardiness and a very adaptable and rugged constitution. Their popularity remains even after more than 150 years. There are newer more colorful hybrids - especially those based on r. yakusimanum - which are also excellent and tend not to grow as enormous, but the Ironclads are still a great place to start.

Kenneth Cox's book, Rhododendrons and Azaleas, A Color Guide is a great source for seeing and learning about what exists in the world of rhododendrons.

Also, more shade means more height and fewer leaves. Full sun usually means a shorter plant with more leaves. It can also mean more lacebug problems, so be aware.