Temp tolerance question - Orchid Board

Dusty Ol' Man · #1 03-12-2021, 10:59 AM

I am looking at some miniatures to add to the collection. Perusing Andy's website for interesting flowers, I am reading his culture notes and see a lot of warm growers listed as "85 to 88 degrees max". I grow outside in all seasons except winter, when temps can drop into the 30s on occasion. Summertime temps typically hit highs of mid to upper 90s for days on end. Lows usually stay in upper 70s and 80s. Humidity in summer will stay well north of 75%.
Here's the question: Will temps in my range harm plants listed as 10 degrees cooler max according to Andy's list?

Roberta · #2 03-12-2021, 11:37 AM

I take Andy's temperature ranges as an indication only - one can definitely extend the ranges. The low in the ranges is more of the concern, end even that can be extended. But the high is very flexible. For hot summers, if you have shade and air movement so that the leaf temperatures don't go much above whatever the ambient temperature may be, you'll be fine. (When it is very warm, you need to be careful of more direct blasts of sun.)

estación seca · #3 03-12-2021, 01:00 PM

The cooler the nights the better plants tolerate hot days. Many orchids metabolize as succulents and open their pores for gas exchange at night. Approaching 85 degrees the pores open less and less, and the plants may suffocate.

Low elevation plants from the hot tropics typically get warmer nights in habitat. Start with those. You can find that information on IOSPE. I would suggest not trying intermediate temperature plants outside with those night temperatures, unless you bring them into the house during hot weather.

Roberta · #4 03-12-2021, 01:22 PM

Functionally, Andy's "warm" includes plants that don't want to go much below 65 deg F. (pretty much the same for warm-intermidiate, except that they may be able to go a little cooler.) The 88 deg F number probably comes from the fact that it rarely gets warmer than that in his nursery - so the number is verified, but certainly not a "hard" upper limit. His "Cool" or "Cool-intermediate" will typically be fine into the low 40's F. His "Intermediate" has multiple meanings...It could mean "not below about 50 deg F at night", it could mean that he hasn't yet fully determined what is possible with a new plant (pretty much everything can grow Intermediate) or it could mean that if it has a "C" that people in south Florida won't buy it so he'll put "I" instead of "C/I" So, when I get one with the tag that says "I" it means "Inquire" ... to find out how I need to grow it.

Dusty Ol' Man · #5 03-12-2021, 04:01 PM

Quote:

Originally Posted by Roberta

Functionally, Andy's "warm" includes plants that don't want to go much below 65 deg F. (pretty much the same for warm-intermidiate, except that they may be able to go a little cooler.) The 88 deg F number probably comes from the fact that it rarely gets warmer than that in his nursery - so the number is verified, but certainly not a "hard" upper limit. His "Cool" or "Cool-intermediate" will typically be fine into the low 40's F. His "Intermediate" has multiple meanings...It could mean "not below about 50 deg F at night", it could mean that he hasn't yet fully determined what is possible with a new plant (pretty much everything can grow Intermediate) or it could mean that if it has a "C" that people in south Florida won't buy it so he'll put "I" instead of "C/I" So, when I get one with the tag that says "I" it means "Inquire" ... to find out how I need to grow it.

Good idea on the "inquire". Thanks Roberta and ES. These are the ideas I need to make my decisions. Wintering in the house sees temps from ~65 to maybe 70. And lower humidity unless I put them in the grow tent. I will probably do that for any minis I acquire. I can keep the humidity between 70 and 80% and daytime temps up to 73 or so.