Our climate is pleasently weird. Our day temps in the fall reach mid 80s to occasionally 90. However, our night temps get down in the 50s and 40s. This is about perfect for human habitation. However, it creates indecision about watering cactus. This is especially amplified in the greenhouse. Day temperatures inside the GH are warm, while night temperatures get down to sometimes low 50s. I feel like my plants are not all completely dormant by any stretch of the imagination, though many are headed for dormancy. I hate to deprive my plants of water if they want/need it, but don't want to rot anything either. Naturally, being the tightwad I am, I don't want to run any heat in the GH until it is an absolute necessity. So the dilemma is: a) Should I cease water all together for the year? b) Should I water lightly instead of a deep soaking they normally get? c) Should I continue to water normally, and go ahead and heat the GH at night so the roots won't get cold? I must say that I really like our climate, but it makes fall cactus cultivation tricky. The greenhouse seems to make it even trickier.. I'm open to suggestions..
Bill in SC
To water, or not to water?
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Bill in SC
- Posts: 2544
- Joined: Thu Jun 16, 2005 5:17 am
- Location: South Carolina, USA
Learning curve, Bill 
Some species are very sensitive to water with these chilly nights. I would suggest Astrophytums as one that can just decide to rot off even though it is 90F during the day. Others just carry on regardless, and not just the really hardy species, some of the no-frost Mammillarias don't seem to mind damp roots and cool nights. Others, like the very hardy Echinocereus and Escobarias, don't care whether their roots are wet or not, they take up water when they are warm and ignore it when they are cold. It can be quite strange to see a cactus sitting in wet soil and still all shrivelled up just because that's what they do in winter.
The only way to learn what a cactus can take is to kill one
I would suggest not watering any large plants again this year unless they have already been very dry for a while. Large pots take longer than you expect to become 100% dry and large plants have the reserves to go six months without water. In similar conditions here, but with cooler days, I may still water some of the smaller plants again.
Remember, they're cacti, they can go without water
Some species are very sensitive to water with these chilly nights. I would suggest Astrophytums as one that can just decide to rot off even though it is 90F during the day. Others just carry on regardless, and not just the really hardy species, some of the no-frost Mammillarias don't seem to mind damp roots and cool nights. Others, like the very hardy Echinocereus and Escobarias, don't care whether their roots are wet or not, they take up water when they are warm and ignore it when they are cold. It can be quite strange to see a cactus sitting in wet soil and still all shrivelled up just because that's what they do in winter.The only way to learn what a cactus can take is to kill one
I would suggest not watering any large plants again this year unless they have already been very dry for a while. Large pots take longer than you expect to become 100% dry and large plants have the reserves to go six months without water. In similar conditions here, but with cooler days, I may still water some of the smaller plants again.
Remember, they're cacti, they can go without water
--ian
Hi Bill- what Ian said, plus a question about atmospheric humidity and how long your plants tend to stay moist after watering?
I completely cut off all water for the hardy ones who will be outside for the winter and let nature do whatever it does. My growing season is so blasted short here that for the more tender plants, it is a constant dance to try to extend their growing time but get them ready to rest. Fall and spring are the two times when I do not mass water the whole lot, but go by more individualized needs and tolerances.
Peterb
I completely cut off all water for the hardy ones who will be outside for the winter and let nature do whatever it does. My growing season is so blasted short here that for the more tender plants, it is a constant dance to try to extend their growing time but get them ready to rest. Fall and spring are the two times when I do not mass water the whole lot, but go by more individualized needs and tolerances.
Peterb
Well all my hardy's outside are officially on there own. My younger hardy cuttings and starts are now inside and having similar weather to yours Bill.
The ones inside are still seeing a little water which comes from a spray bottle-- this way there not being deprived.
No sense in soaking them and taking unnecessary chances.
The ones inside are still seeing a little water which comes from a spray bottle-- this way there not being deprived.
No sense in soaking them and taking unnecessary chances.
Bill
If it sticks ya or pokes ya, I like it
If it sticks ya or pokes ya, I like it