I apologize for this delayed reply to your gardening question and hope it is still helpful to you.
The glazed or painted terra cotta pots are fine for planting as long as they have a drainage hole in the bottom. Terra cotta tends to wick away moisture from the growing media and thus the mix will dry out faster. Glazing or painting will reduce this loss of moisture but won't affect drainage and so such containers are just fine for planting, and quite ornamental too! A good potting mix will allow plenty of air down into the mix to support healthy root growth so a porous sided container is not necessary.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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