Cattleya orchids have the largest flowers of all orchid varieties. New hybrids keep their blooms for many weeks, but older varieties only bloom for two to three weeks each year. Their flowers are often five inches or more across. Because they're the hardest to grow, once you've learned to grow Cattleya orchids, it's easy to grow the other varieties. All varieties of orchids grow well indoors under lights.
Grow Cattleya orchids in bright, indirect lighting. Do not place the plants directly under an artificial light source; they prefer gentle light because in nature they grow in the shade of trees. Place the orchids are 1-to2-feet away from the lights.
Grow Cattleya orchids at the correct temperatures. Keep them warm during the day--between 72 and 85 degrees Fahrenheit. They like cool nighttime temperatures in the range of 55 to 65 degrees. The hotter the daytime temperatures you are able to provide them, the more flowers they will produce.
Water sparingly. Orchids need to dry out completely before being watered again. If you're in doubt about their need for water, wait another day or two.
Provide Cattleya orchids with high humidity. Run a humidifier in the room where they are growing. Another option is to set the pots of orchids into saucers of small rocks. Fill the saucers with water just to the level of the rocks and as the water evaporates, it humidifies the air around the plant.
Fertilize twice a month with orchid fertilizer that is dissolved in water before applying. Always fertilize the day after a thorough watering to minimize the possibility of burning the roots with the fertilizer.
Repot orchids only when the roots overtake the pot and the growing mixture breaks down into smaller pieces. Use commercially prepared orchid potting mix or equal parts of fir bark, sand, charcoal and perlite.