Some orchids have water-storing organs, and some do not. If you have a type of orchid that has the ability to store water, such as cattleyas or oncidiums, you should allow the orchid to completely dry out before watering. If you have a type of orchid that does not have water-storing organs, such as phalaenopsis or paphiopedilums, you should water the orchid before it is entirely dry.
This is not a type of orchid you’ll want to place on your windowsill, because the stems grow up to four feet high. Phaius orchids have large, strappy leaves, and they usually produce petals that are yellow, purple, or white. Also known as the Nun’s Cap orchid, it is a winter bloomer and makes a great addition to anyone’s garden, regardless of what else is planted there.
The complex mechanisms that orchids have evolved to achieve cross-pollination were investigated by Charles Darwin and described in Fertilisation of Orchids (1862). Orchids have developed highly specialized pollination systems, thus the chances of being pollinated are often scarce, so orchid flowers usually remain receptive for very long periods, rendering unpollinated flowers long-lasting in cultivation. Most orchids deliver pollen in a single mass. Each time pollination succeeds, thousands of ovules can be fertilized.
Cymbidium carry tall stems with many flowers that have a more typical orchid shape. They are easily identified by their grassy leaves, and they readily form large clumps. Most common are the cool-flowering types, which need to experience a cooler winter (nights in the 40s for some time in the fall) in order to initiate flowering. Once the flowers open, they can last for up to two months or more, especially in a cool environment. These are very showy and rewarding plants, and a plant in a six-inch pot can carry three stems with 15 or more flowers each, depending on the type.
Water your orchid early in the morning. This insures complete water evaporation on the foliage as well as the crown by nightfall. If your home is very warm or has low humidity you will most likely need to water more often. The best place to water your plant is in the kitchen sink. Use lukewarm water (do not use salt softened or distilled water) and water your plant for about 15 seconds and be sure to thoroughly wet the media. Then allow the plant to drain for about 15 minutes. It may appear dry but it has had enough water. After the plants are watered, they should be placed so that the pots do not stand in water. Some people like to place the pots on "humidity trays" or in trays or saucers of gravel or pebbles and water. The pot is placed on the pebbles above the water line. This helps to insure that the base of the pot is not immersed in water, increases humidity for the plant, and provides some air circulation under the pot.
Disa is a genus of beautiful plants with rather triangular flowers, often red. They require VERY different care than other types of orchids, so it's easy to kill them if you don't know what you're doing. In particular, they like it wet and should never dry out. The best-known Disa is Disa uniflora, which in South Africa is known as the Pride of Table Mountain.
I wish I could tell you exactly how often to water your phalaenopsis orchids and how much water to give them and be done with this post. Unfortunately, there is no one size fits all answer. When it comes to watering any plants there are lots of factors to consider that’ll make the amounts and regularity vary. I’ll go over all those factors so you can see what will be the best for your own situation.
Run the orchid under water. The easiest way to water an orchid is to hold it under a faucet and run it under room temperature water. If you have an attachment that allows you to diffuse the water, rather than just running it in one strong stream, that's better for the orchid. Water the orchid this way for a full minute, allowing the water to seep through the pot and come out the holes in the bottom.
Always water early in the day so that your orchids dry out by nighttime. The proper frequency of watering will depend on the climatic conditions where you live. In general, water once a week during the winter and twice a week when the weather turns warm and dry. The size of your orchid container also helps determine how often you need to water, regardless of climate conditions. Typically, a 6-inch pot needs water every 7 days and a 4-inch pot needs water every 5 to 6 days.