Use of Aircon for cooling and dehumidifying

[abhikjha]

I am based in Mumbai, India and recently got few cactus. The weather here is very tropical, we have 3 months of heavy rain (Jun to Aug). 2 months of very hot and dry months. Then 3 months of dry season with relatively cooler temperatures and from Feb to May, very hot season. Since it's a tropical place, temperature in night also doesn't drop significantly all year around.

My question is for these plants, to assist in their photosynthesis process, in addition to fan and large window open with full ventilation, should I keep my AC on for few hours (with window open) to make things cooler for plants.

Similarly, in rainy season, in addition to watering these guys less, to dehumidify, can AC be on in a ventilated room for few hours?

Has anyone experimented with these ideas? Sounds logical to me but no idea if it will help the plants.

[One Windowsill]

It might depend on which cacti you have. Some are more tolerant of heat and damp than others. They range across the whole of the Americas from Canada though Brazil to Chile. Epiphyllum and Melocactus would probably love it.

There are some beautiful succulent asclepiads in Maharashtra; Caralluma, Frerea (Boucerosia), Ceropegia. Some other lovely succulents like Euphorbia and Kalanchoe. They might be easier to grow. Do you know about the work of Jagdash Singh Sarkaria? http://kssarkaria.org/cactus/cactus-book2.html

[DaveW]

Generally with terrestrial cacti it is high night temperatures that stop photosynthesis, they being CAM plants. So running the fan at night might keep them growing more than in the day, provided they are not getting burnt by the daytime heat?

https://www.thoughtco.com/cam-plants-su ... ert-419197

[Aiko]

Keeping them cool during the day would probably not be the best solution. Keeping them cool at night definately will! So just let them be during the day (maybe prevent them from scorching?) and provide cold at night. I don't know how big of a collection you have. If not very much, you might think about putting them in a refridgerator during the night. It will be dark anyway. When the sun comes, you can put them back in the light. Probably not take out and place back in twice every day with pleasure, but maybe it is not that bad for just a short period of time in the warmer time of the year? A refridgerator will be more efficient than an air conditioner.

[mikethecactusguy]

Wouldn't air circulation be a bit more important? Air movement around the space they are kept in? If it gets down to the 70's F at night wouldn't that be enough of a temperature drop to help photosynthesis?
The temp swings last year for me were 110F during the day and 75 F at night. All my plants loved it and really grew.

[abhikjha]

Thanks everyone! I am planning to buy more of Melocactus as I understand that it's more suitable in climate like ours.
Keeping in freeze sounds very drastic idea, wouldn't absence of air circulation will eventually kills these?
Lowest temperature it reaches here is 24-25 C in night and max it goes to 37-38 C, so @mike, do you think my Gymnocalcyium, Echinopsis, Echinopsis will bloom in this weather and more importantly, will they survive?

[Steve Johnson]

Lowest temperature it reaches here is 24-25 C in night and max it goes to 37-38 C...

Overnight lows for desert cacti in the spring/summer growing season should be in the range of 13-23C, so unfortunately 24-25C lows are pushing it for anything other than jungle cacti and the so-called "desert tropicals" such as Melocactus and Discocactus. Besides Melos and Discos, there may be other Brazilian species that would be suited to your climate.

[mikethecactusguy]

Steve has made a good point of looking at Jungle Cacti or desert tropicals.
On the other hand if you have the resources and the cash, climate control in a greenhouse is obtainable. That's what grower do.
It would fun to be able to set up multiple enclosed controlled environments for growing different species in. Lights, HVAC . It could be fun.

[abhikjha]

Thanks guys for replying. I bought few melos and discos which should be more suitable for my climate. I will do the experiment of running AC for few hours with proper ventilation to see the effect of it on plants, will post update later. Any idea how will Astrophytum fare in this climate? Looked for some info on web but couldn't find anything helpful. After Gymnos and now melos in terms of quantity, I have quite a few Astrophytums (A. Asterias, Myriostigma, Ornatum).