Laelia purpurata is without doubt one of the most spectacular species of the Cattleya Alliance you can grow. A native of Brazil, it is the national flower of that country with many shows dedicated exclusively to this species. As a result, there are many clones and if you have lots of space you can have a large variety.
The plants are fairly large and need a good deal of sun in order to bloom. The flowers are often 6 to 7 inches, or 15-18 centimeters, across usually with white petals and sepals and a large bright lip, normally purple or reddish although there are varieties which are alba (white) and some all pink. There are even clones which have a bluish tinge (var. coerulea) but these are generally very expensive and hard to find. Some Laelia purpuratas have a very nice fragrance during the day. The inflorescence will normally have four or five flowers on it and generally they will all open within about one day. When they are all open they make a spectacular display.
These orchids require many of the same cultural needs as other big Cattleyas. Morning and evening sun, high humidity and good air circulation are required. I keep mine in a corner where it receives almost constant sun year round and is in the direct path of a fan to keep good air circulation. It is generally listed as an intermediate temperature grower, but I have good luck with it in my high heat greenhouse. Ideally, it needs nighttime temperatures in the 58-60 degree Fahrenheit range, or 14.5-15 degrees Celsius, and highs around 85 degrees Fahrenheit, or 29 degrees Celsius. It is rather a large plant and can reach 22 inches when both pseudobulb and leaf are taken into account. Fortunately, it seems to normally grow in an erect manner, so it does not take up great amounts of bench space.
Flowering is normally in May through June in the United States. Give the plant a couple of weeks rest after the flowers are spent, but start watering again as the new growths start in the fall. The sheath should appear in January or February and will grow rapidly until the plant flowers.
For an online version of the June 2003 article in Orchids Magazine by Arthur Chadwick on Laelia purpurata visit Chadwick Orchids. This is a really informative article with some wonderful photographs of various clones of this spectacular orchid.