nope, you do not need cool temps for flowers

[jldriessnack]

So, I hate to be that person, but I am going to be - most people, even practiced phal growers keep spreading nonsense about these orchids. I want to dispel one of them here for people interested in the truth behind their culture. Keep in mind, all my advice will pertain to windowsill culture ONLY - I do not use a greenhouse or any special equipment.

Inducing Blooms

It is simply not true that phalaenopsis requires a temperature change for blooming. By the way, William Cullina points this out in his book on orchids.

First off, in most of southeast Asia where these orchids grow, no such cold spells of 55-65F occur. In Borneo, night time temperatures are often over 75F, and in Malaysia the average temperature is usually above 75F as well - these are tropical, hot rainforest climates. I have watched dozens of phals bloom under all manner of conditions, from temperatures in the high sixties, to constant temperatures in the 80s and 90s. Phals bloom in every season too, there is no right season. I have had blooms throughout the year and I have big, stemmed phals that I don't even need to fertilize (12+ leaves).

Indeed, the surest way to cause bud blast is to suddenly alter temperatures while buds occur. There may be some species types that need such a cool period, but most phals found these days are complex hybrids that have so much genetic diversity it is ridiculous to suggest they operate like the species types.

[estación seca]

You're correct they will flower without temperature drops. But - it does work. Commercial growers manipulate greenhouse temperatures to provide large cohorts of plants at the same stage of budding/blooming at any time of year. For home growers whose Phals just won't bloom, the fall cooldown often does the trick.

[Ray]

If you look at the species and their flowering habits, you will find that those having white or pink flowers tend to be late-winter boomers precisely because they do experience a cooler, drier spell. Those with red or yellow flowers tend to be more equatorial, do not experience any cool down, and can bloom at any time.

Then we hybridize them, throwing all bets off.

ES is right though, while cooling, strictly speaking, isn’t necessary, thermal manipulation is a useful tool.

[Orchidtinkerer]

Nonsense does get spread a lot.
I could argue this post is the perfect example of such nonsense as temperatures do play a role.
It is true there are differences so the biggest nonsense would be to try to come up with general hypothesis's when each orchid is vastly different to one another and what works for one might be completely different to another, even if they are the same type. What would help more is to find out exactly what makes each and every species flower well, not try it on any old phal and then decide it shall be so for every other orchid in the world too.

There are endless articles pointing out temperatures do play a role, like ES says commercial growers use it to their advantage in certain hybrids to initiate flowering.
Other phals might be summer bloomers.

Cattleyas don't just bloom all at the same time either

This article as far as I am concerned explains it quite well from a hobbyists point of view:

https://staugorchidsociety.org/PDF/AOS4-LightTemp.pdf

But just to point out how little we know and how much more discovering needs to be done which these forum discussion will not shine any new light on, only trying new things will, like this article shows: Floral Induction and Flower Development of Orchids

[jldriessnack]

To summarize what you just said: say nothing until you have the specifics on each individual orchid, hybrid or not.

Okay.

And to the other guy, maybe it helps, or maybe it doesn't hurt. Again, most phals will flower at any time of year above 60F. Way more useful than twiddling over what magic trick will promote the best flowering in a plant found at a home depot.

---------- Post added at 08:06 PM ---------- Previous post was at 07:54 PM ----------

See the journal of Experimental Botany (2006), cited by Steven Frowine in his book Moth Orchids, which states clearly that temperatures below 70F do no promote flowering though they may not hurt it either. There is no need for a specific 10-15 degree drop. There is some evidence that temperatures in the 70s is helpful, but not below that.

[Orchidtinkerer]

no the summary would be reading the articles I published as my summary was actually that nothing we discuss here will shine any new light on it.

I will make the same statement and summarize that your summary is make up theories without any proof to back it till someone comes along and does? You advocate some information when there is no other information, wheras I would prefer no information over made up information for the sake of having information. I did not say don't post anything till you know better as we do actually already know better, you can make up your own conclusions but I can see from your attitude you are only interested in causing a commotion - I am interested in finding out the truth so if you aren't even going to read the articles I posted there certainly isn't any point discussing this any further as you are taking this discussion as a personal insult already when I am only interested in finding out the truth - it is out there.

[jldriessnack]

I literally cited an article and a book that is highly well regarded that discusses it - the book being strictly about phal care. So I don't see what I am 'making up'. Further, it is not an experiment to see if phals can flower in colder weather. If they can then you have confirmed nothing other than that they are capable of flowering in those conditions. It does not prove that they need those conditions to flower. The test is to see WHAT OTHER conditions they flower in. Also I am a hobbyist so...this is my point of view.

---------- Post added at 08:24 PM ---------- Previous post was at 08:21 PM ----------

Also, the article you cited is not a study...I cited an actual study from botany researchers...

[Ray]

I think you’re trying to take a fact or two and paint overly broadly with them.

Originally Posted by jldriessnack

Again, most phals will flower at any time of year above 60F.

I have a commercial grower friend in Central America. He intentionally held a large bunch of phalaenopsis plants at above 85F for several years. Not a single flower spike was generated in that time period, but the plants grew to be extremely large. After allowing them to spend a couple of weeks at 70F, he got a dozen or more spikes - per plant.

Way more useful than twiddling over what magic trick will promote the best flowering in a plant found at a home depot.

Yes, it is a “trick” that uses genetically-programmed triggers.

I’ll also add that in the Texas A&M study, which was published in the AOS magazine, does not argue a bit with your earlier statement, and is the reason millions of in-spike plants are shipped here from Taiwan, the statement was that the reduced-average-temperature requirement was to reliably initiate spikes.

[jldriessnack]

I do not disagree that temperature matters generally, or that it matters for phals to a degree. What I contest is the wives' tale that a SPECIFIC 10-15 degree differential must be created for most phals. What is established is that it can be too hot to flower, like over 85 mostly, and that the 70s are most conducive to flowering. But not a differential or anything in the 60s. I know this from practice, from tropical climates, and the botany studies - not articles.

Quote from your research:

These results indicate that a day/night fluctuation in temperature is not required for inflorescence initiation in these two Phalaenopsis clones. Furthermore, the inhibition of flowering when the day temperature was 29 °C and the night temperature was 17 °C or 23 °C suggests that a warm day temperature inhibits flower initiation in Phalaenopsis.

NOT night temps.

This is what I was saying, though maybe poorly, as my point was that for windowsill growers you will always have, given normal room temperatures, day temps in the low 20s C which is in the 70sF. So yes, you proved my point.

[Orchidtinkerer]

it is a relatively new theory that phals do not need the nightly temperature drop like other orchids do and I see your point although I would have to argue 90F is a bit high, otherwise yes especially phal bellina's are free flowering most of the year so after a bit of miscommunication I think we are in some sort of agreement.

I will however add that I still think a temp drop is beneficial as mentioned in the very first article I posted explaining how orchids produce energy during the day and lose it at night so even if the temp drop is not needed to initiate blooming in phalaenopsis as you have said... it should encourage better flowering.