Check your water. For a long time, serious growers insisted that orchids could only be watered with rainwater. Nowadays, most people just use tap water, and this is fine. However, be aware that treated water may have higher salt content, and some water is high in calcium. If you see deposits forming on your plants, you should seek out a new water source. 

^ Zhang, Guo-Qiang; Liu, Ke-Wei; Li, Zhen; Lohaus, Rolf; Hsiao, Yu-Yun; Niu, Shan-Ce; Wang, Jie-Yu; Lin, Yao-Cheng; Xu, Qing; Chen, Li-Jun; Yoshida, Kouki; Fujiwara, Sumire; Wang, Zhi-Wen; Zhang, Yong-Qiang; Mitsuda, Nobutaka; Wang, Meina; Liu, Guo-Hui; Pecoraro, Lorenzo; Huang, Hui-Xia; Xiao, Xin-Ju; Lin, Min; Wu, Xin-Yi; Wu, Wan-Lin; Chen, You-Yi; Chang, Song-Bin; Sakamoto, Shingo; Ohme-Takagi, Masaru; Yagi, Masafumi; Zeng, Si-Jin; et al. (2017). "The Apostasia genome and the evolution of orchids" (PDF). Nature. 549 (7672): 379–383. doi:10.1038/nature23897. PMID 28902843.
The second type, the nobile Dendrobium, grow warm in the summer but require a cool winter period to induce flowering. They need to experience temperatures in the 40s to low 50s (preferably) in order to flower well. They are distinguished by bearing fuzzy, flat, round, colorful flowers close to stem, which cover most of the stem on a well-flowered plant.
Phalaenopsis, the Moth Orchid, is one of the most commonly available and easiest to grow orchid genera. It is an especially good choice for beginners to orchid growing. They have large, showy flowers that come in a wide variety of colors. Most species have several flowers per stem, but some have more, and others have as few as one or two. There are a great many hybrid varieties on the market.
The Coelogyne orchid genus gets a lot less attention than it deserves. The plants have beautiful, fragrant flowers, can tolerate drought and neglect, and rapidly develop into massive, impressive specimens. The best-known species come from the foothills of the Himalayas, where the elevation produces cool temperatures. The largest-flowered species in the genus, Coelogyne cristata, is one of these cool-growing types.
This tribe is fairly large and consists of four genera — Dendrochilum, Pholidota, Chelonistele, and Coelogyne — and over 300 species. They are native to the tropical and subtropical regions of the Old World. Coelogyne is the most popular genus. Its orchids are characterized by a three-lobed lip that is concave at the base, and a hooded or winged column.
Another type of orchid you can grow at home is what I call the “Thai restaurant orchids.” These types of orchids are Dendrobium hybrids and can be found at Thai restaurants that decorate their tables with freshly-cut flowers. They come in many colors (white, green, purple, pink, yellow and more) and require a fairly warm environment. In fact, they could loose their leaves in the winter when the ambient temperature drops below 60°F (15°C) or so. But the “Thai restaurant orchid” is really just one small group of hybrids within the Dendrobium genus. Dendrobium is actually one of the largest orchid genera.
Also called Cockleshell orchids, they have no fragrance, but they do bloom for several consecutive months, making them appealing for people who want color in their garden for long periods of time. The Encyclia orchid has dangling petals and sepals, which is why some people say it resembles an octopus. It thrives when planted on an orchid mount because this simulates the epiphytic growing conditions found in the wild, and it comes in colors such as yellow-white with purple throats at the top.

If only there was an easy guide or a little water fairy that hovered over your plants and told you exactly when and how much to water. Unfortunately, there isn't. But I think this is one of the satisfying reasons we grow orchids. It's all about balance and instinct—and plenty of patience. Here are some of the factors you need to consider when developing a watering schedule:
There are over 60 varieties of the Vanilla orchid, and unfortunately, it only blooms for one day, opening in the morning and closing at night. They grow in clusters of 12-20 buds, and they are yellow-green in color and reach approximately six inches in length. Just like their name suggests, you can actually get vanilla from these flowers, and the blooms have a nice vanilla scent as well. They have to be mature in order to flower, which can take two to three years, and they grow up to ten feet in height. They do best in a garden or a greenhouse, but never as an indoor plant, and they need vertical support to grow and thrive.
The potting mixture, or growing medium, for a phalaenopsis orchid should be good at both absorbing water and providing airflow to the roots of the plant. Therefore, consider using media such as tree bark, coconut coir, clay pellets, perlite, pumice pebbles, and sphagnum moss, either on their own or blended together. If you live in a humid climate, choose a courser potting mixture that dries quickly and provides the best drainage. On the other hand, those who live in a dry climate should use a finer medium that will dry more slowly and hold more moisture.
Epiphytic orchids, those that grow upon a support, have modified aerial roots that can sometimes be a few meters long. In the older parts of the roots, a modified spongy epidermis, called a velamen, has the function of absorbing humidity. It is made of dead cells and can have a silvery-grey, white or brown appearance. In some orchids, the velamen includes spongy and fibrous bodies near the passage cells, called tilosomes.
This type of orchid has over 200 species and has a star-shaped appearance. Most of them have small- to medium-sized blooms and come in colors such as yellow, white, or light green, although most of them are white. The flower has a wonderful fragrance, needs even amounts of water, and prefers temperatures between 60 and 80 degrees Fahrenheit, mainly because they are not a bulb plant and therefore cannot store water. They also look beautiful in hanging baskets and pots.
Orchid stems are also specialized into what are called pseudobulbs. These are basically expanded stems that allow the plant to store excess water and food. The roots of epiphytic (tree-dwelling) orchids have a special outer layer of dead cells called velamen. Because orchids metabolize slowly in order to not outpace their resources, the roots also absorb slowly, meaning that they need help catching water as it passes by. The velamen cells catch and fill with water as it passes by so that the true root (the core of the root structure) has ample time to access as much water as it can. Velamen is silver-white in color, but becomes transparent when wet, so that when the root is wet it turns green as you are able to see through to the inner structures of the root that contain chlorophyll.
A majority of orchids are perennial epiphytes, which grow anchored to trees or shrubs in the tropics and subtropics. Species such as Angraecum sororium are lithophytes,[24] growing on rocks or very rocky soil. Other orchids (including the majority of temperate Orchidaceae) are terrestrial and can be found in habitat areas such as grasslands or forest.
My favorite type of orchid is the lady slipper orchid because of their strange appearance. They are like no other types of flowers and have pouch-shaped lips. The mostly terrestrial and lithophytic slipper orchids include four genera—Paphiopedilum, Phragmipedium, Cypripedium and Selenipedium. But most Cypripedium and Selenipedium are not plants for the beginner because they can be quite difficult to grow under cultivation unless you live in temperate regions with Cypripedium growing wildly in your back yard!
Also called the Lady’s Slipper orchid, this type of flower is easy to grow and is great for the beginner flower-grower. They come in a wide variety of colors, including cheery colors such as pink, white, and yellow, as well as more somber colors such as brown, burgundy, and near-black tones. In addition, many of the varieties include petals that have bristly hairs, freckles, and even stripes, with an added bonus of specks on some of the varieties’ leaves.
The quality of water used, whether for spraying or watering, is of great importance. Since tap water has often been chemically treated, generally with chlorine, it should be used with caution. The best water for orchids is undoubtedly rainwater. Rainwater, as it passes through the air, dissolves and absorbs many substances such as dust, pollen and other organic matter. This enriched rainwater contributes to the nourishment of the plant.
Orchids of all types have also often been sought by collectors of both species and hybrids. Many hundreds of societies and clubs worldwide have been established. These can be small, local clubs, or larger, national organisations such as the American Orchid Society. Both serve to encourage cultivation and collection of orchids, but some go further by concentrating on conservation or research.