Every year I lose a couple of containers to breakage, but I can usually anticipate which ones those will be. My shallow bowls have lasted me three winters already. There is a chip out of one, but that's because a chair fell on it in a windstorm one summer. Sometimes I move the bowls next to the house for the winter, but I left them out this year and they were okay.
Shallow Bowl Planters, January 2006

The containers I lose are the orange terra cotta pots, which always flake and crack. They are not made for our climate, even the fancy IKEA ones that are supposedly frost-friendly. I also made the mistake of leaving a thin ceramic pot outside for the winter, and it cracked right in half.
IKEA Pot after Winter 2008

A few years ago, I had some light concrete troughs (something similar to hypertufa, maybe), and seeing how thick they were, you'd think they would last a long time. Unfortunately, the material was full of open spaces that let the water in and they simply fell apart after the second winter. I did manage to get two summers out of them, though.
Concrete Trough Planter, Summer 2004
(only lasted one winter)

The containers that work best for me -- the ones I don't need to empty or move for the winter -- are:
- cast iron urns (mine could use a coat of paint now after 4 years -- I'll probably spray them with some black Tremclad)
- large, 1" thick ceramic pots from the garden centre
- plastic containers (they are quite effective when grouped together, mixed in with ceramic containers -- I usually choose black or dark green, in at least a 12" size)
- my "stone-look" containers that are actually made of resin
Pansies in the Cast-Iron Urn, Spring 2008

Thick-Walled Ceramic Container, Spring 2007

Mixed Planters, Summer 2006
(white bowl was a freebie)

Stone-Look Planter with Echeveria*

* Although the planter easily survives the winter, I have to plant a new echeveria every year, since they are not winter-hardy.
With the larger, heavy ceramic containers and the urns, I only replace the top one-third to one-half of the soil every year. I dig out the spent soil and put it in the composter, then I top up with potting soil, plant my container plants and make sure they have the right fertilizer (I use those slow-release granules -- feed once and forget!). Depending on the kind of plants you grow, most roots don't draw that heavily from the deeper soil anyway, so I don't think it's necessary to change it every year.
Cast-Iron Urns, Summer 2006

Specifically regarding the shallow bowls, someone asked me if I replace the soil that gets blown away by the wind. Well, the short answer is no. That's because I don't lose soil to wind. These bowls are planted with tight-packed hens'n'chicks (sempervivum). Any remaining space I "mulch" with pea gravel.
Pea Gravel Mulch in Shallow Bowl Planter

Photos belong to kbgardenblog.blogspot.com and may not be used without permission.
It's a very nice look, and the gravel keeps the soil from being blown away. Also, even though the bowls are shallow, I still only half-fill them, so the sides of the bowl will also protect the soil from the wind. Sempervivum do not require a lot of soil to thrive, and if you group different ones together they make a nice show.





































