Temp Diff for Phal to set blooms earlier
 

I want to have my phals bloom earlier this year. They are presently under lights at 75-80 degrees with lots of new roots and new leafs.

In the past, I would move them outdoors in the fall as low temps drop to the 60's.

Right now, my outdoor temps are 90 highs and 70 lows. Would the drop from 90 to 70 initiate the bloom cycle? How many days/nights of this would be required to set the blooms?

Essentially, I want to start the bloom setting cycle in August instead of October.

Any suggestions or comments would be really appreciated. Thanks

Frank

Hi Frank

I have read somewhere that commersial growers of phal. multi hybrids use air conditioners to lower the temperature below 65 F to initiate flowering. With that in mind you could have some problem.

/M

Hi Frank,

I have wanted to do the same thing with a few of my phals in the past from their windowsill growing spot.

However, as I have been searching the internet, I have found that many sources say that many phals will not set a spike if they are constantly exposed to temperatures from 85-90+ degrees Fahrenheit.

What I ended up doing was keeping the phals in their windowsill for the daytime and then during the evening, I would move them to my basement (approx. 65 F) until first thing in the morning. I did this for 2 weeks and then let them stay in the windowsill.

This helped my phals set a spike and bloom early in the past. Hopefully this helps!

Bill

P.S. I have also heard that using a certain balance of fertilizer can also help to "force" a bloom a bit early. I believe it had something to do with the phosphorus levels.

I just started putting my non blooming phals in my wine cellar at night, temp around 56-57. A grower said after 5 weeks the phals should begin to spike. Time will tell I guess good luck.

It may be coincidence but flower initiation on Fall/Winter blooming phals corresponds to a shorter day length as well as a lower temperature ? As to the low temperatures mentioned - mine probably didn't go below 68f and 99% flowered. I also think that micro conditions are important - humidity, light, watering, fertilising etc.
I moved my non-flowering phal to a cooler room for the next few weeks, so I am doing my own experiment....

As I understand it comercial growers keep them warm, then drop the temperatures to initiate spiking, and they do it at any time of year which is why you see blooming phals in the shops all year long.

However, to ensure they set a spike, they first keep them warm enough to inhibit spiking for 18+ months, as well as feeding with high nitrogen in that time. This actually inhibits flowering an encourages growth ensuring the plant is strong and over-due for flowering before they drop the temperatures and lower the nitrogen.

My understanding is that a drop in temperatures will initiate it, rather than needing a particular temperature, and that it doesn't need a night/day difference. However unless the plant is ready to flower it won't make any difference. Many of mine set spikes in June/July this year, which was cold for the time of year over here. Most of those that did though were ones which had not flowered in a long time (one of them had not flowered in a couple of years).

I doubt that you need the 18+ months as we in sweden often get our phals to flower just before christmas every year. The tmperaturedrop in most windows due to colder weather in the end of September in Sweden initiate flowering and after about 90 days the flowersopen, just before christmas.
You are though right that commersial growers keep their phal at hig temperature for growth until they initiate flowering.

No I don't think you need that long, many of mine flower ever year. However that long ensures that a very high percentage of them are ready to flower.

What I was really trying to say is that if an orchid is not ready the temperature drop alone will not make it flower. Nurseries use the temperature drop, but they also ensure the plants are ready to flower by extending their growing period over the standard year cycle.

I think keeping them from blooming for 18+ months is to try and increase flower size, flower count, and multiple spikes. When a healthy Phal. has stored up that much energy it's next blooming is bound to be a grand show.

Dr. Yin-Tung Wang, then at Texas A&M, published a study in "Orchids" in which it was shown that it is not a day/night temperature drop that initiated spikes in phals. Rather is was a decrease in the average growing temperature that was important, and that it was about a 15°F reduction in the average over a 10-day to two week period that was most reliable.

Further, the spikes developed and grew better if the plants were returned to a very warm environment after such a decrease.