Control of Flowering in Cattleyas
by Herbert Hager

This was previously published in The Proceedings of the Second World Orchid Confrence, Cambridge, Mass., 1958, and reprinted in the AOS Bulletin vol. 28, no. 3, pp.163-164.

Used with premission of the Hager Family.

Copyright 2005

Ladies and gentlemen, it is indeed an honor and pleasure to address such a distinguished group of orchid growers and enthusiasts.

I hope the few words I have to offer will be of some help to those interested in control of flowering and growing of Cattleyas. I don't propose to be an expert on this subject, but feel the work I have done with lights in speeding up growth and flowering control will lead to a better understanding of the requirements of this genus.

Most of my work in controlling flowering in Cattleyas has been done with Cattleya labiata and its hybrids. This species lends itself well to control with artificial light, due to its normally flowering on a shortening day.

Lights, added to this shortening day to the extent of 16 hours, will withhold flowering until lights are removed and the day is again shortened.

The more Cattleya labiata in a hybrid and the closer to the last crossing, the more control is obtained.

I might add, I can only give my own experiences and have found that Cattleya labiata can be controlled by a very low amount of light. A 15-watt light spaced every 20 square feet has withheld flowering for me with success. But I have also found that by increasing the wattage to 100-150 watts, with lights spaced a 6 foot intervals over each bench, it will also stimulate growth to the extent that flowering can be maintained every 6 months instead of the normal 12-month period.

In my area (Santa Cruz, California), by giving added artificial lights, making the day length 14 to 16 hours on about June 5th and removing them October 10th or about 125 days later, with a growing temperature af 65° nights, 80° days, flowers are ready to cut December 15, or 65 days after discontinuing the lights. These flowers are then cut, the plants again put under artificial lights, 16 hours, 150 watts, for 3 1/2 months to April 1st. Lights are then removed and plants are shaded with black cloth for 60 days, a temperature of 65° nights, 80-85° days, allowing the plants only 8 hours of daylight, until flowers are open and again ready to be cut. The cycle is then complete. It is important to mention that time of flowering from bud initiation can also be altered by temperature manipulation.

   55° - 70°  60°-78°  70°-85°
 3/4" bud  67 days  50 days  36 days
 1-2" bud  53 days  38 days  28 days
 2-3" bud  42 days  24 days  18 days
 3-4" bud  30 days  20 days  12-14 days

This, I'm sure, points out the importance of temperature in controlling flowering and growing. To prove my point on the stimulating effect of artificial light on Cattleyas, I put light on some plants of Cattleya mossiae.

This species normally flowers from May to July in my area. In order to flower these plants earlier, I have found the following effective. I grow these plants at a normal temperature of 65° nights, 80° days, from time of flowering until new growth is made up, about September 1st. At this time, I drop the temperature to set buds - to 55°F - 70°F or 75°F - until buds show in sheath about December 1, then the temperature is increased to normal 65° - 80°, lights are added about January 15th when buds are about 1/4-inch in length in sheath, with 16 hours of daylight. Flowers can be cut by March 10th (about 25 days from time buds are 1/4-inch in length).

Plants with buds 1/4-inch in length in January 15 without lights were cut May 1st (56 days later), when grown at a normal temperature of 65°F - 80°F. Here again time of flower opening can be altered again by manipulating the growing temperature.

So, I find again by adding artificial lights flowering can be speeded up in this Cattleya from 56 to 25 days. I believe it is well worth the extra money spent on lights.

A few points I feel necessary to get the best results in lights are:

1.) Give as much daylight as possible during any dull weather - grow plants hard.

2.) Plants should be fed to speed up growth with lights.

3.) Don't try to control Cattleya hybrids that have backgrounds of questionable periods of flowering. Hybridists are breeding plants specifically for control of flowering. Use them.

4.) For the amateur, remember if you try to control the flowering of your Cattleyas, close them off from other plants in the house or you may find that your other plants may not bloom. It has happened that in the growing of Cattleyas in the home, labiata and its hybrids won't flower if you are a late reader.

I hope some of you will gain something from these notes I've made, and I feel if we go home after this Conference with only one idea, to improve this idea will be well worth the time spent listening to any of the speaker's experiences.