"Cardinal's Roost" is a hybrid of a Zygopetalum, a class of orchids that are desirable for their long-lasting blooms. In fact, they are often used as cut flowers, according to information published by Beautiful Orchids. "Cardinal's Roost" features deep, midnight-blue flowers. For that reason, they are often called "Midnight Blue" orchids or simply "Cardinal" orchids, although the latter implies crimson-colored flowers. Care of cardinal orchids is similar to that of other orchids, with extra attention to watering practices.
Orchids in general require loose, well-draining planting medium, and Zygopetelum orchids are no exception to this rule. Commercial potting soils are not right for orchids. Instead, plant your cardinal orchid in fine tree bark or a commercial planting medium formulated specifically for orchids.
Zygopetalum orchids prefer a climate with moderate heat, in the range of 55 to 75 degrees Fahrenheit, according to information published by Texas A&M University. Extended exposure to temperatures around 80 degrees F may inhibit the plant from blooming. Never allow your cardinal orchid to experience freezing temperatures, as they are not frost-tolerant.
Zygopetelums have somewhat tricky watering needs. On the one hand, too little water will cause the leaves to turn yellow and shorten the life of the blooms. Too much water in the soil can lead to root rot. Water enough so that the soil stays barely moist. Information published by Texas A&M University suggests watering when the pot becomes light and the planting medium is not yet dry.
Place your cardinal orchid in a location where it will receive bright but indirect light, with some filtered or dappled afternoon shade. Intense, direct sunlight will scorch the leaves. In fact, the leaves can tell you how much light the plant is getting. Light-green leaves that have a tinge of yellow indicate the maximum amount of light has been reached, while dark green leaves indicate a need for more light.
Fertilize your cardinal orchid with a high-nitrogen fertilizer once a month from February through July. Switch to a low-nitrogen fertilizer in August, and use through January. Add the fertilizer to the water you use for watering, and use the amount recommended on the label for the size and age of your orchid.