I learned on another forum that you should water succulents in the evening on hot days. Because succulents use a form of photosynthesis call CAM (Crassulacean Acid Metabolism) and halt their uptake of water during periods of intense sunlight and heat.

With CAM photosynthesis the stomata on leaves stay closed during the day and open at night which allows transpiration which allows the uptake of water. During the night the plants take in CO2 and store it as starches for use in photosynthesis during the day. Oxygen is released during the night also.

So the main point is with CAM plants on hot days the stomata are closed which means no
transpiration which means no uptake of water during the day.

That is true...however from what I have experienced with my plants..you will be dangerously inviting the possibility of fungal or bacterial infection, depending on how cool the nights are. So what I do is to water early in the morning directly on the root zone only, before the sun hits my plants. As I understand it the stomates are closed for sure on the leaves, but the established plants, those roots are still taking in moisture. It helps cool down the roots, before the hot blazing sun comes about, and by night time, as the media is still moist, then it can fully take up more that it needs.

Consideration too on the location where you are growing your succulents, whether indoors or outdoors. Indoors, it takes much longer time to dry out, so watering in the evening for me is a big no-no.

Also have to consider what type of leaf the succulent has..like the Adeniums, Plumerias and some Euphorbias, they have thinner leaves, not the succulent type, but they have caudex or some thicker stems..these plants will surely like to be treated as tropicals, so water in the day is needed.

Oh, need watering help here. My newly potted cacti were just watered (at late night) after a week of drying period under lot sunlight and summer heat. Immediately I saw the water sinking under soil top. Next day, my cacti didn't show sign of happiness or sadness. And now two days later, all soil top look as dry as b4 watering! Although all plants look same as usual, seeing the drying soil top I am very tempted again to water them all, but not sure I should. Please advise. Thanks

Hi Fiat, if you know you have just watered it the day before or in this case last night, then do not water yet again. Top portion maybe dry because it is more in contact with air, but inner parts may still be wet. The cacti will just hoard the water it got before in its stems and it will still be good a few more days without water. If I am really in doubt, sometimes I get a bamboo skewer and stick it in soil, or I put a big rock beside my succulent. If I pick up that rock and it still shows damp below, then soil below is still wet, so I do not water. Or if it still a really small plant, after watering I lift the container just to have a sense how it feels fully watered. When it has gone drier, that container will be much lighter, so I know I can water again.

Underwatering is not bad for these plants, overwatering kills it faster, when roots rot below. I really do not prefer watering at night, but it is your choice. Sometimes with these cacti and succulents, the hardest thing to do is to give them the gentle neglect it needs.

Great info, @adamgreen.

I've heard that it's better to water in the mornings, but sometimes that isn't possible (if you're like me running around like a mad woman just to get out the door, LOL).

If I have time I do a quick check on my non-succulents to see if they look desperate for water (i.e., won't make it through the day without water). It usually cools down after sunset here, but during this heat spell it's only dipped down to the high 60s (and pretty humid because of a tropical storm off Mexico now) so I think it's OK to water in the afternoon, which I've been doing.

I wonder if the dew point has anything to do with whether it's OK to water in the late afternoon/evenings?

It's been so dry in SoCal that I can't remember the last time I've seen dew or any kind of moisture on any outside surface in the mornings.

Dew points are fascinating to me (know nothing about meteorology) -- I've been in Flagstaff AZ and Boise ID in February and March when the morning temps were about 18F and run outside after my shower to see if my hair would freeze, LOL.

But in both places there was no ice because the dew point was lower than the air temperature.

Relative humidity goes higher at night @arapaho415, so it is a good time for the succulents to really take in all the moisture in the air as their stomates are open at night as well. So if there is moisture in the air, the plant will not lose soil moisture quickly.

So that is another thing with night time watering for them..too wet soil, and increased humidity at night, it may not kill them out right, but it will affect them sooner or later, leaves go lanky, aside from inviting more potential for fungal and bacterial issues. Too warm and moist conditions will accelarate production of fungal spores and bacterial production. It would be nice if it is really breezy, it will not stay muggy.

Fiat do you have Cactus or Succulents. Cactus can be dry for a very long time but cannot be wet for long at all before they will die.

Cactus can be dry for months, wet they will die in a month. Cactus you want the soil to look dry. If it looks wet for more than 2 days it is time to worry that you have over watered. My cactus soil looks dry one hr after watering.

Hi Tarev, It's Thursday night I watered them. Well, I think I am much embarrassed by myself that you have reminded me so many times checking wetness with a bamboo skewer and I haven't done it even once. Please pardon me for the ignorance. Ok, this time I first peek down under the small rocks and still see dry soil underneath. Then I use a thin chopstick pushing down into soil about 3". The upper 2" is dry and the bottom 1" shows a bit wet (dark soil). So I assume it'll be safe for maybe 3 more days w/o water. Thank you.

Oh, Cinta. Just saw your post. Thank you for reminding me that cacti are dry-loving plants. Now you bring up a new one for me: cacti vs succulents. I haven't thought about it yet. So I think my Crassula Tetragona and Pachyphytum are succ; other aloes are cacti? If so, maybe succ need bit more water? Thanks

Hi Fiat....don't be embarrassed!! Even the most intelligent person had to learn from the beginning....and there is ALWAYS new stuff to know. This group is a great place to start!! Good luck with your plants....keep us posted

Fiat don't be embarrassed ever with us. I cannot speak for others but I killed so many Cactus when I first started I bet when they saw me coming they dived under the counter because they new it was sudden death if they went home with me. I have been at this for more years than I want to admit and I am still asking questions and killing a few plants along the way.

Succulents are different than the cactus. They were a little harder for me to kill because they can take a little more water. Cactus seem to hate water. They are use to being in the desert and it does not rain in the desert.

I

Is it all right to water during the evening when there are triple digit temperatures during the day? Things have begun to really cool off here by the way.

I really will not encourage that evening watering Adam. We also get triple digit here, and I do not do that. With the other types of plants, they can benefit with evening watering, since their stomates are also open during daytime. But with succulents and cacti, though they do the CAM exchange at night, once there is moisture in the air, they will utilize that air moisture first before they use up their stash, so they may use the moisture in the soil, but they do not drink it all up that night, so roots might end up sitting too moist far longer.

Fiat, we all learn everyday..I was negligent too before, but I am adjusting my watering habits too, as season changes, as conditions change. And I have killed my fair share of succulents too. As to which is cacti and which are succulents...here is something to remember...all cacti are succulents, but not all succulents are cacti. Knowing what type of succulent you have will also help you adjust your watering regimen. There are tropical, desert and alpine succulents, then knowing if they have dormancy periods. Hey I use to successfully kill Plumerias...finally got my bearings right I think..after 3 years My existing nemesis are Pleiospilos nelli and Lithops..just cannot get my timing right with these cute succulents..but I will keep trying!

Something I have learned during these past few years, most cacti, they can take a bit more frequent watering, if grown outdoors, in full sun, in full heat. It is their active growing time. Indoor grown cacti, have to keep them a bit more drier, since it takes longer to dry. But during cold season, keep them much more drier, they have adapted to slow down growth to no growth at all during very cold temps, so they have no need for any extra moisture uptake. But whichever watering manner or frequency done, very important, keep their media very well draining.

Hey Fiat - here is a wikipedia link on what is a cactus http://en.wikipedia.org/wiki/C... I just read parts of it, I didn't realize that all cactus except for one type, come from the americas
Aloe are succulents.

Greg, Thanks for the wiki link. Ok, as Tarev indicated that all cacti are succ, but not all succ are cacti, so we know all this kind of plants are succ including all cacti. Now how do we distinguish those special succ which are not cacti? Are my Crassula Tetragona and Pachyphytum not cacti? If not, do they need bit more water? Just curious.

Fiat I think most of your plants were succulents (cacti are going to have spines, or spikes or whatever you want to call them!) I think if your weather, including night time temps, is still warm, then you could water because they should be growing.

That is almost right Greg...cacti have spines. But there are other succulents with spines, that are not cacti.

I found this page: gives some info on how to differentiate another type of spiny succulent from a typical cacti:
http://www.weekendgardener.net...

But to keep it simple for me...with spine could be cacti....succulents in general would be any plant that holds/hoards water either in its leaves, in its stems/caudex, or in its roots.

Thanks Tarev - now I know! Until I forget again No I think I will remember now!

Cinta said: I cannot speak for others but I killed so many Cactus when I first started I bet when they saw me coming they dived under the counter because they new it was sudden death if they went home with me. I have been at this for more years than I want to admit and I am still asking questions and killing a few plants along the way.

I had to laugh at this Cinta!! I have gone through sooooo many plants that my Hubby says that plant stores have posters saying "DO NOT SELL PLANTS TO THIS PERSON!!!" with my picture on them!! Sad to say that I really deserved it!! FINALLY starting to get a few that will survive for me!!

Fiat, I used to think succulent meant it likes to be moist all of the time. Oops! That's pretty much exactly wrong. Horribly sad list of dead ones over the years, until I started wondering why and started to investigate. Now I'm pretty sure, if I separated my plants into 2 categories: C/S vs. all other plants, the number of different C/S plants would be much higher. There's just so many, and once I stopped killing them by watering them like leafy tropicals, it's rare that one croaks. So much more fun that way, all made possible by seeking, soliciting some help. If I can keep about 98% of the C/S alive that I buy/get in probably the worst possible place, humid, rainy, steamy south AL, anyone has a shot! Looks like you actually live in a place where the weather is helpful, not a hindrance. Sending good vibes to you!

I've wondered about dew before too. Every morning here, it looks like it rained overnight. So much dew it drips off of trees, and runs down car windows.

Cacti have areoles. If I've grasped what I've read correctly, it's this feature that sets them apart?

Regarding culture, I'd love to hear everyone's thoughts... how important is it for a person to know if their C/S is a C or not? I realize the true cacti can survive being dry longer (pls correct if this is a wrong general assumption,) but is there a more specific plan than, "get the amount of light right, let dry, then add water?" (Assuming I'm not using a soil that will facilitate root rot?) That's pretty much my plan for all plants, C/S or not, and things are going well, but as said above, I always want to learn more and improve my results. Had plants around my whole life, but keeping C/S alive is new to me over the very recent past. It's extremely exciting, and holy cow, the selection of wild, cool, beautiful plants!! And they're not all prickly, not even close. Wish I'd woken up and smelled the C/S coffee a couple decades ago. I'd now have some C/S plants that aren't teeny tiny.

Ok so no watering in the evening.