What triggers an orchid to bloom?
 

Many of the orchids we grow come from the southern hemisphere. Do these orchids, being grown in the northern hemisphere bloom 6 months differently than their cousins in the southern hemisphere? Light and temperature cycles are the opposite in the southern hemisphere. Does that make a difference? Along the same vein, do clones, living in different locations and somewhat different conditions bloom at the same time or do they develop there own schedule?
Thank you for your thoughts.

Many plants "plan their activities" around the photoperiod, or length of the day. Since, for example Christmas Day where I live could be 10F, but is likely to be 70F this year, temperature is not a good way of a plant telling what season it is. But the length of the day on Dec 25 at a given latitude is pretty consistent. The influence of photoperiod is less important the closer one gets to the equator, since the seasonal variation in day length is less pronounced than at higher latitudes. Of course seasons are reversed in the southern hemisphere, which can be confusing to strongly seasonal plants. I have personally worked with tuberous Drosera and some winter growing terrestrial orchids which were imported from Australia during their summer dormancy. Which is of course is our winter and the time they should be in full active growth. The acclimation to the seasons in the opposite hemisphere takes a couple of growing season before the plants grow in their normal cycle.. Now on many tropical plants which just grow as long as conditions are good and flower when they feel good, the adjustment would likely be seamless.

And if you are growing in the home under lights, you may be obtaining similar conditions in temp and day length to the topics.

What triggers an orchid to bloom?
 

I think that the goal to grow orchids well is to simulate their native environment. So, if you are able to simulate the conditions of the tropics during your winter they will act as if they were in the native environment. If you use your local climate (to make your life easier) and is able to provide similar conditions only during your summer, i think the orchid will adapt to that and change their cycle. At least, that's my theory.


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As far as I'm concerned, there is no "pat" answer for the original question.

Some of the "driving forces" for orchids blooming include:

• changes in day length
• seasonal changes in temperature
• a period of dormancy due to a drastic reduction, then resumption in nutritional supply.
• changes in air pressure (so one "expert" surmised about a particular dendrobium)
• a last-ditch effort to carry on the gene pool, as a response to some trauma.

I agree with Ray. Different conditions bring on bloom in different genus and some multiple conditions can cause bloom, as in the last ditch effort when about to expire, or just very good culture for that genus.

The ones I keep are hybrids. I have paphs, phals,catt, zygo and , onc. All hybrids on these kinds. For me good growth is the best way to get a rebloom. As long as the new growth can fully mature and is in good health and in the right condition they bloom. Conditions don't even need to be perfect they just need to be good.

The hybrids kind of just bloom when they are ready they kind of have a season I have some that bloom in different seasons. Some take a year to rebloom others 6 months. It all depends on the plant and it's health I think.

Keep a plant healthy and happy it will bloom just give it time. People that first get into orchids don't realizes how long it can take for them to reboom. I keep a lot so when one is out of bloom I have another comming into bloom.

I think you are all overlooking the primary but obvious stimulation for blooming and that is the fact that the plant growth has to be mature to bloom. All the temp/day length changes in the world will not cause a plant to bloom if a growth is not in a mature state to do so.

It might be mature enough to bloom, but many of my Catts are pushing buds before the growth itself is anywhere mature and hasn't even got its leaves fully grown and opened up. Those growths seem to mature after or during bloom time.

Plants can't see a calendar (or if they can, they aren't talking.) They pay attention to seasons and day length. So yes, summer blooming plants are in bloom in November-December-January in the southern hemisphere and June-July-August in the northern hemisphere.

The easiest way to establish most plants in the other hemisphere is by seed, but this isn't so easy with orchids. If you have a lab, though, seasonality of seed planting doesn't matter.