In my opinion they get ugly when they too big and the percentage bloom verses ugly plant favors the ugly plant, so I tend to start new plants often and dispose of the remnants of the old plant. Al

My potted ones grow more slowly so I can get away with 3 years on some types (mild winters so no dormancy).

Root pruning won't cure the "uglies" (thanks calistoga). Hard top pruning (root some of those) will force out new growth.

I am with Al on this - I have about 4 zonal geraniums in hanging baskets, and about 6 more in pots by the pool deck. I hard prune them about once or twice a year, and feed them well with fertilizer after that. But I end up changing them every 3 years with brand new plants altogether. Just did that last weekend in fact when Home Depot was having their 1.99 sale on zonal geraniums.

Another thing to keep in mind is that the zonal geraniums come in the annual vs perennial variety - thats probably just labeling for legal reasons. But the perennial ones are definitely hardier than the annual ones.

My experience has been like those of you who responded -- 3 years!

Annual and perennial!? That's news to me. How can you tell one from another? (I also have Martha Washington's which get woody, and freeze every year, but they come back.)
RB

The ones I have bought have it labeled - Annual vs Perennial.