Professional Grower's Notes on Blooming Phalaenopsis/Phals
Diana in Houston nicely shared her notes under a thread called "Phal Insider Growers info." Arthur and others added information and had questions. The following is primarily Diana's editing of that original post. Thanks Diana!
I just came from my orchid club meeting where we had a local wholesale commercial phalaenopsis grower as the speaker. It was interesting but nothing special until he and Dr. Wang, our mentor and reknown orchid researcher, started talking about what was required to make phals bloom, and have more flowers, (a specialty of Dr. Wang's). Here's the scoop: 1. A phal NOT blooming can be determined by temperature AND light. A commercial grower can KEEP PHALS FROM BLOOMING until a particular time by keeping the temperature above 82 degrees. However, a cheaper way is to shade the greenhouse with 50% shade cloth. 2. To initiate spiking, the temperature must remain consistantly below 82 degrees. A temperature of 90 degrees, even for a short time, will prevent spiking. 3. To have more flowers on a spike, from the time the spike is 2 inches, until it is 8 inches, the temperature must remain consistantly between 65 degrees and 77 degrees. Day and night difference is not involved. This commercial grower gets the phals as 4 to 6 inch bare root plants from Taiwan. He pots them in 4 inch pots and grows them on for about 6 months, at which time they go into 6 inch pots. He then keeps the benches of phals he wants to spike under plastic with an air conditioner (on 24 hours a day) at each end until the spikes are 8 inches tall (approximately 6 weeks). He then moves them out until they have 4 or 5 flowers open, then delivers them to jobbers.
As you can see in Dr. Wang's information above, withholding blooming to produce bigger and better blooming is standard practice in the industry. (Notice he says that growers raise the temperature to prevent blooming, but he added that greater shading will produce the same effect.) Nothing specific was mentioned about phal species. I would assume that the species that make up the modern hybrids would be responsive. I failed to mention that the commercial grower said that he stops the cooling when the spikes reach 8 inches, but that it was for economic reasons. He has the plastic cover on an arched frame about two feet above the benches. He could have it higher and let the spikes reach a greater height by cooling for a longer time, but it is better for him to have fewer flowers and be able to treat another batch of plants, then to have fewer plants, but more spectacular flowers. Also, Both he and Dr. Wang use RO water and cal/mag fertilizer exclusively. Doesnt the air conditioning lower the humidity? That question came up at the meeting. Larry said that, between the area being closely covered with plastic, and the regular watering schedule, (hand watered, not automated) the humidity did not drop low enough to affect the orchids. Posted by: ArthurM NSW AUST (My Page) on Sun, Aug 1, 04 at 17:59 There is a little problem in that most of the above relates to spring flowering Phalaenopsis. Add Doritis to the equation and i'm not sure what will happen. Perhaps this is why I've had so much trouble getting Doritaenopsis Tamara to rebloom though I found the start of flowering spike the other day and where it is sitting on the windowsill has been down to 12C. This autumn flowering trigger must relate to one of the species that appears in the ancestry of most modern hybrids...But there are some that initiate flowering in early spring such as the large white that I auctioned at our last OS meeting purely because it grew enormous leaves and outgrew its welcome. Flowered December so counting back 110 days spike would have started about late August (Spring Here). Phal amablis is in flower now so flowering was initiated when it was still warm. Doritis pulcherrima flowers summer as does Phal. violacea so expect different behaviour from primary hybrids.
If you read down the thread, you see that Dr. Wang actually says just to 'increase the shade' if you want to withhold flowering until a later time. How you cool your phals is largely determined by where you live, and whether you can keep them outdoors at a range that will not threaten them for long enough to get a lot of flowers on each spike. If you have ever seen Dr. Wang's phals, there are as many as 50 flowers on one plant, and the flowers are huge. The spikes can be three feet long. That is produced by carefully controlled temperatures and feeding, not just submitting them to some cool weather. I live in the southern tip of Texas, and the weather dips down to the low 40's or upper 30's several times each winter and the upper 90's in the summer. My phals are outside year round. Some of them rather then whether they will spike or not bloom beautifully, with short but full spikes. Others are loaded with flowers, but they are small. This depends on their heritage. Some are just finishing their bloom now, in August, and others will bloom in the cooler weather and throughout the winter. The only rule that seems to hold is that most of them thrive with a steady cool period. How long that period is will determine the quantity and perfection of the flowers,