Lowering night temps

[ryrycochinco]

I know a decrease in night temp is important to encourage bloom. The problem is I don't know how, when, or how long. My orchids are all sending out new growths so I'm guessing now is the time. It's really HoT so the a/c runs day and night but even then the it's 75 degrees. there's a extra a/c near my growing space but it's big and would seems like a waste of electricity to run all night. I've thought of alternatives like raising the day temp to compensate, or waiting till fall because most of my plants are summer fall/winter bloomers. Could my summer bloomers wait till fall.

[quiltergal]

Nope, it's too early unless you have summer bloomers in which case it's too late.

The fall/winter bloomers will set spikes in the fall when temps drop naturally at night. Sometimes just opening a window at night for a few days is all it takes.

Summer bloomers don't really need the drop in temps to trigger spikes.

It also depends on what plants you are growing. In Phals the above is true, but for many other plants it's the change in the number of hours of daylight that does the trick, and temp plays no role.

It's also important to remember that plants go through several cycles in a year. A blooming cycle, an active growth cycle and some also need a rest cycle. If yours are actively growing that's a good thing. The bigger they get the more energy they will have for the next bloom cycle. That means a higher flower count and larger blooms for you!

[Weaver]

I dont have much to add, but I will say the only way I have been able to get my cymbidiums to rebloom is with a period of cold nights. And, last year I didnt put them out for their "blast" until november/december-ish, so for them, at least, you still have plenty of time, at least from my experience. This summer, here in the Seattle area, we havent gotten OUT of the 50s at night yet, so I will be curious to see if the cyms still need some cold in late fall, or if this extended coldish summer nights will trigger them already (they are spending the summer outside). Good luck!

[Orchid126]

The cool down, as quiltergal says, will come naturally in the early fall here on the east coast. The cool down need only be 15 degrees. Therefore, if the day is 85 and it drops to 70 at night, there's the 15 degrees. And this drop need only be for a few weeks. This applies mainly to phals. Nobile dendrobiums can take a lot more cold and will bloom better for it. So it depends on the type of orchid you're growing. Some are affected not by temp but by the length of the day, either shorter or longer.