wow...thanks for all your thoughts on this! Kaktus makes an excellent point about what we should really consider in watering during the winter and I agree. Most of my plants get very little water but are under pretty good lights (ViparspectraP XS1000 LED); they are pretty happy in a chilly room so I think I just will water only as needed. Stush2019, don't know where you live but your post made me think about my mangaves (10) and hope they will overwinter in my greenhouse where they are currently under fleece cloth too. I lost a couple last winter because of the heat fluctuations but I have the heater on a thermostat now so it won't get below 36. I hope the mangaves can take that. bumplbea I'm glad we don't have the humidity issues here that you refer to ....it's plenty wet but not so much inside...whew!
I always enjoy reading your posts Baja_Costero and this one is no different....I must say when I look at your locale I'm envious...I've spent some time in Baja and loved it. Many fond memories and longings. Lucky you!

We always read that we have to wait until the soil dry (completely) dry before next watering, is it to wait until it is dry like the pot on the right? Personally I will water them when they are like pot on the left or even earlier, too worry that their roots will dry and dead.

If what you are doing is not killing them and they are growing, I am sure it is fine. If the conditions are right cacti do not mind being a bit wet, but if someone was growing the same plant in say cool humid conditions and watered like that I would bet it would provide problems.

To volunteer as a resident of a cool and humid climate, that is something I would try to avoid. I mean, bone dry is not necessarily the goal, but close.

The way I try to look at it, there's generally no issue with most desert cacti going bone dry on a regular basis (in between being watered, regularly if not necessarily every time). But there is no particular advantage to leaving them bone dry for any extended time, when conditions are favorable otherwise.

I guess if you live in a hot place then it makes more sense to be proactive about watering, if the alternative would be allowing the roots to sit bone dry for any extended period while evaporation (and transpiration) are high.

This is in fact the area that I keep on trying / monitoring. I am also live in a very humid area. Any guidelines on how long the bone dry period that they can hold on? In a lot of cases where I repot or treat the unhealthy plants. I found out that quite a few of them are having dried/dead roots. I suspected that some of the plants are always in the cycle of growing new roots, then the roots dried and dead, regrow new roots and dried, so it will like dormant on top, and struggling at the bottom. Of course I can not really proof them, still monitoring and make a lot of assumptions. As for the 3 pots above, their soil are quite dry, if we put the soil on a cloth, the cloth will not get wet at all, if put them on a paper towel, the paper towel will absorb some humidity and become wrinkled. The droplets that we saw are like the sweat on the outer part of a glass with cold water inside.

In our climate most cacti don't have much of a problem going dry for an extra week or two in containers, once in a while, given average humidity >70% and high temperatures generally in the 60s or 70s F. Some plants will tend to lose their roots if they stay dry for more than half the time, something in that range.

Arh, for me with the temperature ranges from 80F to 95F , then I will have a much higher chance of the roots to dry dead then, I water the succulent every 3 to 10 days, depends on their exposure to direct sun, for most of the plants 5 days in average. But usually I never water them to complete saturation / multiple pass like you did, worry that the hot sun will cook the roots.
Another question, whenever you water the plant, can you feel the hot air released from the soil, and your face / cheek will feel the hot air?
Until now I am still looking for the right formula on when to water, plus the complete saturation thing.

One thing to keep in mind is that it is very much possible for plants that died from too much water and or humidity to show dried up shriveled roots. You would expect the most common response to be wet rot, but that is not necessarily always how it shows.
By the time you see a distressed plant the roots your are seeing may be the dried up shriveled remains whereas the bulk of the roots has rotted away.

But warm humidity is something very different than cold humidity when it comes to cacti (and most other succulents). I can tell you that most of my cacti prefer the monsoon part of the summer (if it actually happens) when it is hot and relatively speaking humid over the hotter much drier part of the summer that we always get.

I see, will keep one monitoring and get the right formula. Thanks a lot

There is also something about rain water which is better (in a qualitative sense) than our tap water, even after I correct the pH and add a trickle of nutrients to it. Rain seems to be less likely to cause adverse outcomes when it occurs in excess (though there are clearly limits). And proper rain is more likely to cause plants to green up, or reinflate and change posture, or rejuvenate somehow, especially if they have been enduring a degree of drought stress.

Our freak summer hurricane rainfall this year was an interesting contrast to the usual drought (patio plants on a weekly schedule). The storm came more or less when I would have watered anyway, but the rain went on for a while and the result was kind of dramatic. Three agaves lost their roots as a result, but all the Aeoniums took it as an excuse to kick into growth a month early. A bunch of seasonal growers (eg. Pachycormus) were also awakened early.

Usually I use ground/well water for the plants, as they are more or less free and no chlorine like tap water, only when I have problem with the pump or the well then I will use tap water. My ground water has high level of mineral content like manganese, iron and calcium.
As for rain water, less than 10% of my C&S has exposed to rain, and we don't keep/store rain water, too many mosquitoes will pay eggs on those.

Our tap water is ground water (no chlorine) and it does have a lot of those dissolved salts. And then I add Mg/Ca bisulfate when I acidify (about 3 table spoons a week in 300 liters for my potted plants).

I got a kit to measure hardness of different types, made for aquarium use and available in well stocked fish/pet stores.

https://apifishcare.com/produc...

and our tap water is consistently hard (pH >9). In fact it is roughly the same pH as the purified alkaline water that we drink.

I use only purified water for my baby seedlings (especially the ones under plastic) and for most of my clay pots, to avoid crust buildup. I also acidify the purified water.

In any case, the rain water must be a bit of a relief after all these solutes, especially when it comes in abundance over an extended period. It provides a far better flush of the soil than I could achieve otherwise.