Phal fert question

[Ray]

Keep in mind that it's an AVERAGE growing temperature drop that's needed.

If the plants are grown with 70's at night and 90's in the daytime, a 10-degree reduction at night won't be sufficient. Your plants still might spike, but if you can take the average down sufficiently, the likelihood increases significantly.

[Celtic100]

Hmm. So that says to me 70's is too warm at nite? But a 10 degree drop would take it to 60 which isn't cool enough?? Since you say to take the average down sufficiently I guess that's what you are saying. Also, I thought a reduction in the temp differential is what we are looking for i.e., if I look at your example of 90 to 70 we are talking a 20 degree differential so to me that works. Must be the heat this summer - I'm a little fuzzy. Thanks.

[Cntry]

Some of my Phals are just blooming now. I am getting 3 to 4 blooms on them. Nothing like what I got when I purchased them. I am not sure why or if I did something wrong. They are out side and temps are 80's to 90's in the day. At night its in the 70's.

[silken]

They need an overall drop of both day and night. So if it's 90 in the day and 70 at night now, then 75 or 80 in the day and 55 to 60 at night would be better in fall. Even 75 or 80 seems too warm to me tho for a fall temperature drop. Mine do get quite warm in summer but come fall it is pretty easy to lower the temps significantly both day and night.

Many orchids do need a 15 degree diurnal range (variance from night and day) as well to bloom.

[Joseia]

Originally Posted by silken

They need an overall drop of both day and night. So if it's 90 in the day and 70 at night now, then 75 or 80 in the day and 55 to 60 at night would be better in fall. Even 75 or 80 seems too warm to me tho for a fall temperature drop. Mine do get quite warm in summer but come fall it is pretty easy to lower the temps significantly both day and night.

Many orchids do need a 15 degree diurnal range (variance from night and day) as well to bloom.

Thanks for the explanation to both you and Ray. To be honest, I never really understood what was meant when I have seen similar comments in the past. My phals at home experience a day to night temp difference of around 12 degrees F and they have been blooming nicely. But they aren't getting the average temp drop mentioned above. The phals in the office don't get much of a change in day to night temps, but when cooler weather arrives, they are probably getting the average temp drop since they are right up against the windows.

So my question: is it sufficient to have one or the other temp changes (temp/night change, average temp change) but not necessarily both to initiate spikes?

[Ray]

Originally Posted by Celtic100

Hmm. So that says to me 70's is too warm at nite? But a 10 degree drop would take it to 60 which isn't cool enough?? Since you say to take the average down sufficiently I guess that's what you are saying. Also, I thought a reduction in the temp differential is what we are looking for i.e., if I look at your example of 90 to 70 we are talking a 20 degree differential so to me that works. Must be the heat this summer - I'm a little fuzzy. Thanks.

No, I think you missed the point. It's not the day/night differential that matters.

If you have 90-degree days and 70 at night, your AVERAGE is 80. If you drop the nighttime temp to 60, you have only decreased the average temperature to 75.

A few years against, I tracked the daily average temps, then plotted the 2-week running average, in an effort to evaluate the concept. 222 out of 365 days I had a diurnal range of 15 degrees or more - occurring in every month of the year - but spiking did not become initiated until several weeks after they plants saw a consistent average drop of that much.

Read more here.

As to my point about reliability, plants want to bloom - it's their sexual expression; don't you want to express yours??? - but we, unknowingly, most of the time, put up barriers to that through improper culture. Given a reasonable opportunity (parents are out of the house, so at least some degree of "proper conditions" are restored), they will try to take that opportunity to bloom. The better those conditions are (2 weeks of parents away would do that), the more likely the sexual expression will happen.

[Celtic100]

Ah, I see now and you have made your point in a most commanding manner. I will follow to the best of my ability to allow for orchid sexual expression, and also, keep an eye on my parental vacations. Thanks again...

[Celtic100]

I have revisited this thread and post the following question. Is a temp of 52 tooooooo low? I see 55 as the bottom line in many posts but thought I'd see if I could do 52. I have a nice cold mud room for a nite time temp and then brought inside for a high of about 75 day time temp (when it's sunny.) Thanks.

[Orchid Whisperer]

My personal experience is that my hybrid Phals survive 50 F with no problem. I grow my Phals outdoors in the spring, summer & fall. They always get a seasonal cool down to nights of around 50F (sometimes cooler) before I bring them indoors. They have all either bloomed recently or are spiking now.

Bonus: when I move them outdoors in the spring, often the nights are cooler outdoors than they are in the house, and I often get a sprintime spike too.

[Celtic100]

Thanks so much for that good info. Especially that the temp can even go lower than 50 as that may happen in this mudroom. I'll give it a try. I can always get another one at Wegman's if it doesn't work out. Thanks again.