My personal method, the Bucket Method, is illustrated in this post:
I have lots of Tillies, so this works for me. Outdoor Tillies can be sprayed down with a hose every couple of days. But let's start at the beginning....
Tillandsias are New World epiphytes, so they live in a variety of climates. Some live in lush rainforests, others in arid semi-deserts. Some live high up in trees where they get lots of sun, others, down low where there's nothing but shade.
Tillandsias use CAM respiration, just like succulents and cacti. They take up CO2 at night, rather than during the day, and they lose very little water from their stomata. This means they can go for long periods without any water. But more than 10 days and they'll start to take on damage. A dry month or more can mean death for many species. The tips of the leaves will brown and curl, the plant will seem very dry, like a cornhusk, and drought spots will appear within the leaves.
I don't have enough time to keep my 100 Tillies on separate watering schedules, so I bucket-water them about every 4-5 days, then mist them every day they aren't bucket-watered. This has kept them very happy so far. I add special Tillandsia fertilizer to the water on the first watering of the month. Tillie fertilizer has no boron, zinc or copper, all of which hurt them. Many commercial orchid fertilizers are fine for Tillies, and some cactus fertilizers are OK, though the one I use is specially compounded by a Tillandsia nursery in California. I make sure the water is very slightly acidic, about 5.5pH. If you live in a hard water area like I do, just add 4-5 drops of white or rice vinegar to every liter of water, and you'll be in the ballpark. Mist with filtered tap water or rainwater.
Don't let the plants sit in water, ever. They won't be able to respire if they are always wet, and if water is kept on the base, or bulb, of the plant, it will rot. Some Tillies, like T. intermedia, T. caput medusae, or T. xerographica, should be drained/dried on their sides or upside down so they drain properly and don't retain water.
|T. intermedia, drying upside-down.|
Tillandsias respire mostly at night, so it's best to water in the morning or afternoon. That means their leaves are nice and dry by the time they have to do their main gas exchange.
Please feel free to leave any questions in the comments section. The next care guide post will be about light and placement of Tillandsias within the home.