Oncidium blooming trigger

[biology]

I know that phalaenopsis require a difference between night and day temperatures to bloom, but what about oncidiums? Are they sensitive to day length or temperature, or do they just bloom when the newest pseudobulbs mature?

[jkofferdahl]

All of the above.

[chantrelle]

Originally Posted by biology

I know that phalaenopsis require a difference between night and day temperatures to bloom, but what about oncidiums? Are they sensitive to day length or temperature, or do they just bloom when the newest pseudobulbs mature?

I'm also very interested to get more details about this.

How long should day length be increased or decreased ?

How much colder the night should be ?

[Dollythehun]

Mine appear to bloom when the pbulbs are mature. Never noticed a difference in temp.

[Ray]

In my experience, oncidiums are not "triggered" by any environmental cue, but as Dolly said, it's a matter of maturation and the build-up of sufficient "reserves".

Back top the original post, it is not just a day/night difference that triggers blooming in phals. While at Texas A&M, Dr. Yin-Tung Wang showed that it takes is a 10-15F reduction in average growing temperature for about two weeks to initiate spiking.

After reading his results, I tracked the temperatures in my greenhouse for a full calendar year. It was a year in which I had that big of a temperature swing in every month, but I didn't get two consecutive weeks of that much lower average until October, and the plants spiked about six weeks later.

[Selmo]

interesting chart, it shows a 33-35F temp steady decline in temp from the warmsest point to where it flattens out in november. where your plants spiked

[Ray]

That was 2011, and those were the average daily outdoor temps. I had my thermostat set to kick in whenever the greenhouse temp dropped to 50, but did no cooling.

[NYCorchidman]

I'll add in my two cents.

Phalaenopsis are not triggered to spike by the day & night temperature difference. This is needed for pretty much all plants to function properly.

Phalaenopsis, the common hybrids we see offered in the market and their parental species, for the most part spike as a result of decreasing temperature of both day and the night. This is not my opinion but rather proven results of study done by PhD Wang in Texas A&M University.
There was an article regarding this in the orchid magazine years back.

Now, certain phalaenopsis, mainly the fragrant lowland tropical with shiny light green round leaves with waxy flowers, they either bloom in the summer or just about whenever.

Back to Oncidium, many of these plants occur near the Equator in the mid to high altitude in general.
So I would think day and night temperature would stay relatively the same throughout the year while rainfall amount might be the only thing that changes if ever, although these area is known to be wet all the time whether it is "wet" or "dry" season.

Some species might be picky, but hybrids in general seem very easy going in blooming.
Usually they should flower when the new growth matures. This can occur over two three times a year given good conditions and this makes them very popular orchid group along with colorful numerous flowers.

[estación seca]

"Oncidium" means a lot of different things. Just in the genus Oncidium, as currently understood by taxonimists, there are species from many different elevations and climate regimes.

If we expand to other genera in the Oncidium tribe, and all the intergeneric crosses, there are even more plants to consider.

Most species Oncidium - as currently understood, including the former genus Odontoglossum - bloom once per year. This may be spring, summer, fall or winter in different species.

Many intergeneric Oncidium tribe hybrids bloom multiple times per year, either with or as soon as they finish a new growth. Is this because they have lost mechanisms triggering blooming at certain times, or is bloom time controlled by new growth initiation? I don't know.