Why potting mix is important
It's impossible to properly discuss watering without considering rooting media. Orchids are commonly potted in one of two media: moss or bark. Both are perfectly good materials, but they require somewhat different care. Moss acts like a sponge, and it takes a lot longer to dry out. Thus, for orchids like Phalaenopsis and Cattleya that need to dry out thoroughly before watering, moss requires a longer wait before watering and is less forgiving of too-frequent watering. Bark, which holds little water, poses less risk for these orchids. The rule of thumb: water the day before the medium is completely dry.
Lady slipper and nun's orchids enjoy conditions on the moist side and they'll do better if you don't let them go completely dry. Moss is a good choice for them, supplying adequate water for longer intervals between watering. Can these moisture lovers be grown in bark, too? Sure, if it's fine-textured. But be prepared to water more frequently.
Orchid media decomposes over time, especially bark. When this happens, the bark loses the fast-draining properties that many orchids prefer. That's why it's necessary to repot in new bark every year or two. It's a simple two-step process. Just remove the orchid from the old bark, which you can just throw on the compost pile. Clip off dead roots (which will be dark and shriveled, compared to the firm, fleshy, light-color healthy roots). Place the orchid back into the pot and refill it with new bark.
A common recommendation is fertilising with quarter-strength, water-soluble fertiliser each time you water. That means whatever the fertiliser label says to mix into the water, use only one-fourth that amount, and add it every time you water. This constant "spoon-feeding" is good for plants and ensures you never have to worry about when you fertilised last.
Orchids and light
Homes generally have dim light (from a plant's perspective), so orchids that tolerate low light levels stand a better chance than those that require strong light. An east-facing windowsill is a great spot to grow your orchid. The sunshine from an unscreened south-facing window can be a bit too bright (and hot), but a sheer curtain offers just the right amount of filtering. Or set the orchid back away from the window so that it's not constantly in strong indirect light.
West-facing windows make it simply too hot for orchids. However, with some filtering (as you would with a south-facing window) you might make a go of it. The light at a north window is usually just too dim for orchids.
You may want to use a blooming orchid as a table centrepiece or put it somewhere away from a window. There's no harm in doing so, as long as you return the orchid to better light once it's done blooming.
Orchids and humidity
These orchids don't require rainforest humidity and may do OK in your home without extra measures. But the dry atmosphere of an air-conditioned home can be challenging. That's why a daily mist, or setting orchids on a moist bed of gravel, helps success.
One precaution: orchid pots should sit atop the gravel, not nestled within it. Otherwise, you risk wicking moisture up through the bottom of the pot and saturating the roots.
This article originally appeared on Better Homes and Gardens US.