Thank you for the information. I'll start using that temp.

Hope you have a good Christmas!

Why use warm water? I've always used room temp water, would never occur to me to use warm.

Room temp water for me is too cool for the plants. It would kill them. So, I plan to use warm water...not hot, just warm.

It's been cold here already. It will be colder.

I always prefer to water with warm water in winter......and on the mornings of a bright sunny day so that any excess water or wet foliage dries/evaporates before evening.

Whatever temperature rain would be in their native land would probably be the best.

Room temp water is best if you keep at 80 degrees. My house is closer to 65 so it would hurt my plants. Again, water at 80 degrees would dry off faster and a shot of warmth would help keep fungus at bay. As Chris said, in the bright sunny mornings so to make sure of plant drying out before bedtime. Also to note that this is once a month or less depending on what I see. Also what works for some (proven results) doesn't always work for all. Many conditions changes everything and I still loose plants this time of year so I have lots to learn myself.

Technically and depending on specific soil and environmental properties, water is always in a state of evaporation. Evaporation is a change from liquid to gas state. This state change causes the supporting material to cool down.

In other words, evaporation extracts heat from the environment. So a basic and overly simplified claim can be made that watering at room temperature (could) eventually causes a temperature drop in the rootzone. This is why I always use water with a temperature well above room temperature.

If you want to test this 'temperature drop by evaporation' just dip a temperature sensor in some alcohol and let it evaporate. A temperature drop of 5C is expected within seconds. It's a bit nitpicking, but hey .. I care for my plants and such.

Oyster, Thanks for the basic law of Air Conditioning. That's the principle use of an expansion valve in the AC system. Wish I could have explained it so well.