Watering in heat wave

[Eric Williams]

I agree most cacti may go to sleep in this heat, so it would be a waste to water them. Does this apply to Lithops ? My Lithops look as if they need a good drink of Dwr Cymru (Welsh Water) at the moment. Cheers

[Diane]

I think it would be safer to leave them for the moment, Eric. They get very heat stressed in habitat, and cope with such conditions, but cooler weather is coming soon! (Thank goodness!) so maybe just sit it out until then.
I'm sure iann will have some good advice if he reads this.

[AnTTun]

I remember a lesson I got about 100000000000000000000 years ago when I got carried away with C&S: 'if they go dormant because of the heat wave (and they will) just spray them, never water'. My teacher could have been wrong but I still follow that rule...

[Eric Williams]

Good tip AnTTun, thanks.

[Aiko]

Today a 75 year old heat record was broken up here. The temperature reached 40,7C, old record was 38,6C. I haven't been in my greenhouse, but I wonder if it would have been over 50C.

Even the camels in a zoo thought it was hot enough to try to cool down in some water:

[rodsmith]

The outdoor temperature in my garden here in the north midlands reached 32 deg C in the shade yesterday afternoon. In my conservatory, with windows and door wide open and fan on, the highest was 37 deg. C in shade. The temperature this morning here is significantly lower. I haven't watered my succulent plants all week but after today's reduction in heat I'll probably start again tomorrow.

[Tony R]

If I had time I would move every plant outside for a day and let them enjoy this gentle rain falling right now in Kent.
It take too long though to move 2,500+ plants.
If only I could just remove the roof of the greenhouse!

[habanerocat]

Surely during cooler night temperatures cacti would take in water if given the opportunity during a heat wave.
What night time temperature would be needed?

[wildedges]

If I had time I would move every plant outside for a day and let them enjoy this gentle rain falling right now in Kent.
It take too long though to move 2,500+ plants.
If only I could just remove the roof of the greenhouse!

I was fantasising yesterday about a greenhouse on rails that I could slide away during the right conditions.

[Terry S.]

Some work on Arizonan cacti reported in "The Cactus Primer" showed that night temperature needs to be below 18C for the stomata to open to carry out CAM.