When it comes to houseplants, terra cotta is so commonly available and inexpensive that it can seem like the "industry standard pot".
Here's what they don't tell you: terra cotta pots, unless maintained properly, are generally best suited for plants from arid climates. Namely, cacti and succulents.
Because cacti and succulents mostly come from the deserts of the Earth, they're designed to adapt to as little water as possible (in fact, the way most plant parents kill them is by over-watering them). The ground that they naturally grow in is typically almost completely devoid of moisture, which can be hard to reproduce in a ceramic or plastic pot because the water takes so long to evaporate out of the soil on its own.
Enter the terra cotta pot! Terra cotta is extremely porous and water leaves it quickly, meaning the soil at all depths within the pot has a chance to dry out. Water that sits for any amount of time at any level of the soil under a desert plant is bad news, so this is a valuable quality that can save your arid plant where in another pot it might begin to rot.
Terra cotta pots can be an option for every variety of houseplant in a pinch, but it takes extra work to ensure that your plants are happy planted in terra cotta. If you're determined to use terra cotta, there are two options you can pursue.
Option one is to update your watering schedule with the terra cotta factor in mind. You should be checking the soil of those plants much more frequently by putting a finger all the way into the soil and seeing how long it takes after a watering for the soil to dry out, and then incorporating that knowledge into a new watering schedule. Where in a different pot you might be watering only once a week, you might now be watering twice a week to keep the soil from drying out too much under plants that want moist soil.
Option two is to maintain your terra cotta in such a way that the water in the soil cannot evaporate out through those pores. We accomplish this by adding a layer of water into the terra cotta itself.
Soak the terra cotta in water periodically until the material has thoroughly absorbed water into all of its walls. This internal layer of water will keep water from evaporating out of the soil. Repeat this whenever the terra cotta lightens in color again.
Impurities found in the water that you use to re-hydrate your terra cotta will inundate it over time with those contaminants. To clear the terra cotta of that buildup, remove the plant from the pot and soak the pot in vinegar and water mixed together. Make sure to scrub the planter while it's soaking! The vinegar will clear the pores in the pot of those impurities. After it has soaked, rinse the vinegar away completely. Once the vinegar is no longer present, re-plant your plant into the pot.
To sum up: terra cotta is best for plants from arid climates, and to plant other kinds of plants into terra cotta requires either more frequent watering or soaking and cleaning the pot itself periodically. It's usually less work in the long run to find another kind of planter to plant your non-arid plants into - we recommend concrete or ceramic planters. But for cacti and succulents, it's absolutely perfect!