Watering

masscactus · Post by **masscactus** » Wed Jun 20, 2007 5:07 pm

Hello, more questions.

When is the best time to water - morning or evening?

When is weather a watering concern - if it is a rainy grey day is it best to wait? For a sunny day? What about humid days?

Plant and pot size - I read constantly that watering 'once a week' is typically ok but that can't be constant. Obviously species dictates as well but how to determine overall - a plant in a 2" pot vs. a plant in a 12" pot?

I really appreciate the feedback I have been getting - I am asking basic questions in an effort to review and challenge what I know (or think I know).

Post by **CoronaCactus** » Wed Jun 20, 2007 5:33 pm

wow, I was about to ask the exact same thing...as our schedules usually dictate we water in the evenings and sometimes after dark and i was wondering if this was good or not or didn't matter.

peterb · Post by **peterb** » Wed Jun 20, 2007 7:44 pm

Hi- Take everything I say with a grain of salt, because I live in a relatively arid, low humidity environment. So some of what works for me obviously won't work elsewhere.

I grow plants in two basic mixes. One is a soilless mix with Metromix, perlite, volcanic rock called scoria and very coarse sharp pebbly construction sand. 5-2-2-2. The other mix is a soil based mix using local very poor gritty "loam," scoria and sand. 3-2-2. The first mix is for plants that aren't very touchy. The second is for Sclerocacti, Pedios, Echinomastus, Peniocereus, Ariocarpus, some Escobarias, etc.

Some plants are in plastic and some in clay.

I water individual plants when they are dry. The Metromix with plastic has widely varying dry times. The metromix with clay dries fast. The soil mix with plastic or clay can be like a thick mud one day and bone dry the next. So a watering schedule is out of the question.

The exception: very hot days, above about 90F. I water into the early summer about once every two days, soaking everything.

Summer dormancy of some plants means not watering them as summer goes on, so they get moved off to the side.

Some plants can be soaking wet for weeks on end with very few dry days when they are just emerging out of winter dormancy. (Pedios, some Opuntias, Sclero parviflorus).

The only rule I go by is intuition. Careful observation of each individual plant almost every day. My old tendency was to *not water enough* and results have been very fine over the past 8 years or so watering much more than I used to.

peterb

Post by **daiv** » Wed Jun 20, 2007 8:35 pm

I used to think it was bad to water plants in the sun, but have been convinced otherwise. So as for time of day and weather conditions, just go for it (when needed).

Buck Hemenway · Post by **Buck Hemenway** » Wed Jun 20, 2007 8:35 pm

I can say that in general, early morning watering is best for most plants. The surface of the soil is fairly dry when night comes and there is much less chance for various fungi and other rot producing stuff to form in the always more humid night period.

Post by **CoronaCactus** » Wed Jun 20, 2007 9:17 pm

Great! or not...now we're gonna fight over who gets up early to water the plants...

thanks for the info.

parodias · Post by **parodias** » Wed Jun 20, 2007 9:23 pm

Buck Hemenway wrote:I can say that in general, early morning watering is best for most plants. The surface of the soil is fairly dry when night comes and there is much less chance for various fungi and other rot producing stuff to form in the always more humid night period.

I disagree .. C&S are CAM metabolism plants and they have their highest metabolic activities overnight when it is cool(er) and that includes water exchange and uptake (see "The Cactus Primer" Arthur Gibson & Park Nobel)(http://www.hup.harvard.edu/catalog/GIBCAC.html)

iann · Post by **iann** » Wed Jun 20, 2007 10:49 pm

C&S are CAM metabolism plants and they have their highest metabolic activities overnight

I see this idea a lot and it isn't really true. The idea that CAM plants only take up water through their roots at night because that is when they "metabolise" simply isn't true. Night is when the stomata are open, and transpiration potentially pulls lots of water straight through the plant. However, CAM plants behave this way precisely because it is more humid at night and so transpiration is minimised. Furthermore, they can do their night-time stuff even in completely dry soil, and they can take up water through their roots even during the day. A succulent that ignored available water for 50% of the time would be a dead succulent!

Still, if you water at dawn and 90% of it evaporates before dusk then you are maybe restricting the chances of the plant to get what it needs, or at the very least just wasting a lot of water. I water in the morning in cool humid conditions so that the body of the plant and top dressing have the best chance to dry out quickly, fungi and rotting are a big problem in my climate. When the weather is hot I prefer to water late in the day so that the plant gets at least one good night before all the water evaporates (and there is little risk of staying too wet in these conditions).

The question of whether to water in sunny or cloudy conditions is a very good one. Cacti in habitat nearly always get their water when it is cloudy. Other types of plants in my garden appear to react much better to water in cloudy conditions, even low pressure conditions, than they do to water during settled sunny weather. The issue deserves more study but for me it is a non-starter: cacti get watered when the weather is expected to be warm and sunny, the risks of having a wet cactus in cool damp weather for many days or even weeks is just too great in my climate.

Buck Hemenway · Post by **Buck Hemenway** » Wed Jun 20, 2007 11:10 pm

As usual, Ian is the voce of reason. The problem with questions like these are that one questioner is in the NE US where the climate is similar to the UK and the other is in southern California where the temp is 101 deg F today. Even in hot Socal, the risk of fungus is real if watering is done late in the day. Ian's take on cloudy vs sunny weather makes perfect sense, unless you have no cloudy weather. Here the overnight temps will be as much as 40 deg F lower that the daytime highs, so early morning is as good as it gets.

masscactus · Post by **masscactus** » Thu Jun 21, 2007 2:20 am

Question answered, debated, bonus advice given and some botany for good measure. Thanks!

But now...I am worrying about everything!

parodias · Post by **parodias** » Thu Jun 21, 2007 7:57 am

iann wrote:
C&S are CAM metabolism plants and they have their highest metabolic activities overnight
I see this idea a lot and it isn't really true. The idea that CAM plants only take up water through their roots at night because that is when they "metabolise" simply isn't true. Night is when the stomata are open, and transpiration potentially pulls lots of water straight through the plant. However, CAM plants behave this way precisely because it is more humid at night and so transpiration is minimised. Furthermore, they can do their night-time stuff even in completely dry soil, and they can take up water through their roots even during the day. A succulent that ignored available water for 50% of the time would be a dead succulent!
.

I think you should really read that book by Gibson & Nobel .. to me your concepts of CAM metabolism and the chemistry thereof seem at least "incomplete"

.. besides the point was not "if" there was any uptake but "when" water uptake was the most efficiently processed ..

parodias · Post by **parodias** » Thu Jun 21, 2007 8:13 am

Buck Hemenway wrote:As usual, Ian is the voce of reason. The problem with questions like these are that one questioner is in the NE US where the climate is similar to the UK and the other is in southern California where the temp is 101 deg F today. Even in hot Socal, the risk of fungus is real if watering is done late in the day. Ian's take on cloudy vs sunny weather makes perfect sense, unless you have no cloudy weather. Here the overnight temps will be as much as 40 deg F lower that the daytime highs, so early morning is as good as it gets.

YMMV .. I water any time of the day as long as there is some "light" so to speak .. I just do not believe these "fungus" tales

I've been flamed on forums for sustaining that "misting" plants in Spring and Fall to awaken plants and on Summer days at noon for cooling and late evenings for providing moisture are a procedure invented by the devil and that plants would all die by massive fungal attack .. Well if you look at my pictures they're all but massively attacked .. oh & BTW air moisture figures here a bit on the high side, we are happy if it stays at 60%RH mostly it is a lot higher so it may be ideal for fungal and bacterial development ... but with adequate ventilation there just is no such attack .. and I'm only a "stone-throw" away from the UK climate and in the same "climatological air layers (f)tunnel"

Oh & BTW if your temps are really that high & different (day/night) then your eco system is the perfect example for efficient watering in the evenings, it is the type example for CAM metabolism at its best

.. read Gibson & Nobel ! you will see, they happen to understand succulents physiology way beyond average amateurs' interest !

masscactus · Post by **masscactus** » Thu Jun 21, 2007 1:00 pm

OH - one more concerning watering!

Is the soaking preferred as opposed to the top down method?

gduggins · Post by **gduggins** » Thu Jul 19, 2007 8:29 pm

For what its worth...It's very humid (most of the year) where I live...usually above 60% all the time. I grow everything in pots, clay and plastic, actually whatever I can find used. As for watering, it all depends on each individual plant. If you spend as much time with your plans as I think most enthusiasts or maniacs as my wife describes me do, you learn the "feel" or personality of all your plants and you also know how heavy the pot feels when it's REALLY dry and again when it's wet. I learned to water by feel, but prefer to water everything in the morning early or with at least two hours of srong daylight left.

If I water in the evening I make sure no water gets on the plant itself but only the soil. It's not so scientific as most but I haven't lost a pot to rot or fungus in quite a while. I'm sure some of my plants are not growing as rapidly or robustly as they could be, but they're growing. It's been my expreience that when you think the pot is good and dried out, it is usually just the top inch or so that is actually dry and the center of the pot is still very moist so I wait until the pot feels really light before the plant gets a good soaking.
I'm talking cacti not other succulents. I handle non cacti succulents in a similar way...but wait for slight leaf wilt before watering anything that is rot prone.