I think it all comes down to the time frame you're looking at as opposed to what the information says.

Soil, water and sun are big variables also.

Old time local gardeners have the best info as to height in my opinion.

Mike

Tags usually give mature size of the plant which for shrubs is probably about 10 years. It will differ from ultimate size because of course plants don't stop growing after they turn 10 years old. And that ultimate size is quite hard to determine because it will depend greatly on conditions in which the particular plant grows.

Great answer! Mature size - what's typically included on plant tags - is not ultimate size. The longer a plant lives, the bigger it will get, although growth does tend to slow its rate as the plant ages. And I find water has a lot to do with both size estimates - the more water available, the faster and larger plants tend to grow, as long as drainage and other growing conditions are suitable.

Many of the Great Plant Picks size listings are too small.