I really like gas permeable terra cotta containers and choose them most of the time for anything I'm growing on & don't really need to have in an attractive container; though I do enjoy the look of a nicely patinized clay pot. Terra cotta is especially good in situations where the soil is not drying quickly enough, because it allows water vapor transfer through the container walls & bottom. It can, in some cases, allow you to use a soil that you could never use in a glazed or plastic container and maintain optimum vitality, and even if you are using a soil that allows fundamentally sound irrigation practices, I still feel you'd be pressed hard to so readily find containers made of a material less expensive and/or more conducive to good plant vitality.

Typically, arguments will be mounted from a "convenience to the grower" perspective that a plastic pot could be construed as superior, but I would bet that no one will mount a convincing argument that physiologically, a plastic container could be superior to one of terra cotta.
I think that when using plastic containers (and of course, I use them, too), we're all probably sacrificing potential plant vitality on the alter of grower convenience.

Al

I also prefer unglazed terra cotta in almost all situations. The only time I default to plastic is usually with phaleonopsis orchids. I use the clear plastic pots so I can see the roots to know when it want to be watered. I will also sometimes use plastic if I have to pot something up real quick and it's the only thing I have on hand. I also think they're better if you're going to be hanging the plant up.

Commercial growers use plastic because it's cheaper, lighter and more durable. It's just more practical for them, though for personal use I think terra cotta is better for all the reasons Al mentioned. Also, they wick soluble salts out of the soil! I'll usually leave the plant in it's plastic nursery pot though until it's time to be repotted.

For me it depends on what it is -- I use both. For my variety of Crassulacae I use clay, also for my Aloes, Haworthias, Gasterias, some Sans. & a few Hoyas.

Plastic pots for other Sans (depending on their shape, size & weight), most of my Hoyas & the 'houseplantier' plants like Aralias, Anthuriums, Ficus & AVs.

Plastic's better for non-succulent plants, those that don't need to be as dry immediately as others.

Does it make a difference if I paint the clay pots?

All my cacti, Succulents, sans are potted in clay.
Tropicals and sub-tropicals live in plastic or terricota. Though I'm unsure of the difference between plastic and terricota..lol.

Msalex, the only difference I've heard is, brighter colored pots attract more sun than darker..Don't know if this is fact or fiction, but living in IL, I go for bright colors..including walls..every wall in our house is painted semi-gloss white..I've read sunlight bounces off walls, (especially towards light colored pots) and aims at plants..My dh says I haven't any imagination..LOL..Toni

Shame on me buying all my pretty glazed pots! Even the terra cotta pots I have inside are glazed around the bottom. I'm funny about coordination... the plant, pot, and room all have to work together. Even outside I have bright pots that welcome you to my porch, but some are terra cotta, and my Boston ferns are in plastic pots.

Chandres

I read that african violets do not do as well in terra cotta as in plastic, as their stem rests against the rim of the clay it can rot, and that the salts that seep into the clay pot do the violet harm?

Don't know if that's true, but I don't put my violets in unglazed clay, only plastic. But most everything else (under 8 in pot size) gets to live in clay. Looks prettier, and the darned cat doesn't knock 'em over so easy!

About AVs in clay pots--back in the dark ages when I began growing houseplants including African Violets, there were no plastic pots to consider! The routine was to make strips of aluminum foil to slip around the edges of the pots to protect the AV leaves from the accumulated salts. Then somebody came up with the clever idea to dip the top edges of the pots in melted paraffin wax. Worked fine--but plastic is certainly easier, and I know lots of people who grow gorgeous show-quality plants in plastic, and I don't know anyone who uses clay anymore--not that there aren't any of course, just that I don't know 'em. So many things in growing depend on the plants, and the grower, and the climate-- I think it's really hard to make hard-and-fast, always-true statements. I grow some plants in terracotta and some in plastic; sometimes it's because of the plant, and sometimes it's because that's what I have at the time. If I take good care of them they do well. When I don't they don't.

toni, 'clay' and 'terracotta' are the same thing. FYI!

Al, just to clear something up, I did not state that plastic was better than clay. Quite the opposite, actually. I also did not imply that plastic is better because that is what commercial growers do. The reality is that they use plastic because it's cheaper (both to buy and to ship), lighter, almost unbreakable and retains water longer. Personally, it's not my preference but unfortunately that's the way it is. Just because it's more practical for them doesn't mean it's the best thing for the plant, but commercial growers do what they have to to maximize their profits.

And once again, I agree that clay is inarguably the best for 99% of plants!

I should buy one clay pot everytime I visit a spot that sells them so eventually, I would always have one to use. But recycling plastic is what happens-especially to fit inside a decorative pot.

Why do I love those decorative pots my plants ask?

Settle down there, Saucer. (smiling here) I wasn't referring to you. If you look, there is only one person upthread who made a " ... plastic's better ..." statement. We often 'think' it's better because it makes our life easier (less watering) or it's just 'prettier', but the fact is, it's very difficult to mount a case that it's better from a 'plant's vitality' perspective under any circumstances.

I'm not on a crusade to get everyone to grow in clay. ;o) As I mentioned, I have a ton of material in plastic & polypro nursery containers. But I think knowing containers with gas-permeable walls are healthier is just another way of illustrating how important gas exchange in the rootzone and a well-aerated soil are to o/a plant health.

Take care.

Al

Then I apologize for misconstruing your remarks. :)

Rhizo thanks for the explanation..
In that case, I haven't any tericotta. Only TC looking pots. :)
I use unglazed clay for Cac and sux..
I don't consider plastic pots 'prettier' than clay..If anything, ceramic pots are nicer looking than clay/plastic..plants growing in ceramic don't do as well (for me)..plus pets and clumsy people, sometimes knock pots down making a mess; you've got shards of broken glass to clean up. Some people want pretty pots and nice-looking plants, but in some cases, depending on the plant, the two don't work..
Placing ceramic outside, chances are falling and breaking, not to mention sunlight dulling paint..And soaking plants in sink is out of the question.
In my case, it's not pretty pots I'm after, but plants that do well, stay healthy, so using clay and plastic does the job.
Use whatever works for you, be it clay, plastic or ceramic. Toni