Orchids come in different sizes. I have a miniature phal in a 3-inch pot. This orchid needs watering more often than the larger ones in 6″ deep pots. An orchid in a larger pot will need watering less often, but will need more water quantity wise. The material of the pot will also make a difference. Those in plastic will dry out a bit slower than those planted in porous terra cotta.
Did you know there are more than 20,000 types of orchids in the world? That’s more than four times the number of mammal species! While most are found in tropical rainforests and grasslands in far off places, a fair amount are also native to the United States. A favorite in homes worldwide, the “Orchidaceae” family features blooms that are vibrant, tropical and fragrant.
The goal is to get each mix particle to absorb as much water as possible. To give the potting mix enough time to absorb water, place the entire pot in a bowl of water for 10 to 15 minutes, then lift it out and let the excess water drain before putting the pot back in place. This technique works well for orchids potted in clay. Since clay is porous, water penetrates the walls of the pot and is absorbed by the bark.
One of the most interesting things about growing any type of orchid is how they grow. Most of the houseplant orchids and even lady slipper orchids need good air flow around their roots. With indoor orchids, use an orchid potting mix that features some kind of blend of composted bark, expanded clay pellets, hardwood charcoal and peat moss or sand. The mix should create many air pockets for orchid roots to breathe.  

^ Thomas J. Givnish, Daniel Spalink, Mercedes Ames, Stephanie P. Lyon, Steven J. Hunter, Alejandro Zuluaga, William J.D. Iles, Mark A. Clements, Mary T.K. Arroyo, James Leebens-Mack, Lorena Endara, Ricardo Kriebel, Kurt M. Neubig, W. Mark Whitten, Norris H. Williams, and Kenneth M. Cameron. 2015. "Orchid phylogenomics and multiple drivers of their extraordinary diversification". Proceedings of the Royal Society, series B (biological sciences) 282(1814):pages??. doi:10.1098/rspb.2015.1553.[full citation needed]
Cattelya – This orchid is probably best known as the corsage flower, since that is where most people first see it. Of the different varieties of orchid, this is the standard that most growers refer to. Cattleya is a native of South America and loves heat and light. Grow them in rooms that feel almost stuffy and place them where they can get as much sunlight as possible without burning them.
The characteristic that makes these different than many other orchids is their shape, which is triangular, blocky and compact, or thin, whiskery, and elongated. They bloom in the summer and require certain temperatures and humidity levels, so you should research them before you decide to purchase them. They can be tricky to grow and therefore, they are better for people who are more experienced in the garden, and they come in colors such as yellow-orange and have leaves that are a beautiful shade of green.
Orchid flowers are all bilaterally symmetrical with three petals and three sepals. Their seeds develop in capsules and are extremely tiny, sometimes mistaken for dust or spores. Because the seeds are so small, they don’t contain enough nutrition to grow a new plant themselves, so they develop a symbiotic relationship with fungus, which provides the nutrients for them to grow.

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.
Dendrobium species live as epiphytes and lithophytes in New Guinea, Southern China, Thailand, Japan, Australia, New Zealand, Tahiti and more. As a result, it’s hard to generalize how to care for these types of orchids. Some of them require cool nights of 50 to 59°F (10 to 15°C) while some of them require warm temperatures in the 80s°F (27°C). That’s why it’s so important to understand their natural environment so that you can make them happy. Learn more about Dendrobium orchids.
The orchid plant is also unique in its morphology (form or structure). We can begin with the leaves and work our way down to the roots. The leaves of many orchids in cultivation are unique in that they are specifically designed for water conservation (as is true for almost every orchid structure). They have a heavy waxy leaf coating and specialized stomata (openings through which the leaf “breathes”) that help to prevent water loss during transpiration (the act of the plant “breathing”). Many orchids utilize CAM photosynthesis as well, which in essence means that the plants collect materials during the day and then process them at night.