Watering at night or early morning -- does it matter?

[Steve Johnson]

Although I can't back this assertion up, I have a feeling that the question of watering at night vs. early morning may be talked about a lot, and yet may also be relatively unimportant. Does it matter? If so, are there any distinct advantages to watering at night vs. early morning depending on periods of the growing season? My gut feeling is that watering in the morning may be better when overnights are on the cool side, then watering at night in Summer when nights tend to be warmer. If this is even worth responding to, I'd be interested in getting takes from different people based on their climate and preferred potting mix.

To get the ball rolling here -- my overnights are in the mid to upper 50s, and I'll be watering a bunch of cacti early tomorrow morning.

Thanks!

[peterb]

The time of day we water our plants is of utterly, absolutely, completely and totally no consequence whatsoever. (Except perhaps if water droplets act as magnifying lenses and burn the epidermis of plants, a phenomenon that some growers swear has happened to them, but that I have never had happen and have read is impossible due to the focal length of the "lens" created by a beaded drop of water).

But otherwise, yeah, it really, absolutely does not matter one bit, at all.

peterb

[Steve Johnson]

The time of day we water our plants is of utterly, absolutely, completely and totally no consequence whatsoever. (Except perhaps if water droplets act as magnifying lenses and burn the epidermis of plants, a phenomenon that some growers swear has happened to them, but that I have never had happen and have read is impossible due to the focal length of the "lens" created by a beaded drop of water).

But otherwise, yeah, it really, absolutely does not matter one bit, at all.

peterb

Ah, good -- that's what I was hoping to hear! Suppose it was a silly question, but I'm a night owl by nature, and having to get up early in the morning just to water my cacti isn't exactly the way I like to start my weekends. Unless someone else has a persuasive counter-argument, then this old night owl will be watering some plants before he goes to bed tonight.

Thanks, peterb!

[DaveW]

Ask yourself when does it rain in habitat? The answer is it could be day or night. Do you need to leave the water standing in the greenhouse to warm up to greenhouse temperature? People caught in showers in habitat often remark it can be boiling hot one minute but then they are doused in ice cold rain and shivering, but when it stops it warms up rapidly again, that's what our plants are used to.

Do drops of water on a plant act like lenses and burn? Surely not because as soon as the plant surface underneath started to heat up the water itself would conduct the heat away and the drop cool the surface by evaporation. What has sometimes been suggested to happen is as some drops evaporate, if they contain salts or fertilisers, it leaves concentrated chemicals on the plants surface that burn. How true that is would be open to conjecture, but like Peter I have never experienced burn from water droplets.

Should you always water cacti from below as some books suggest, never from above? Well it never rains upwards in habitat and even plants need a wash now and then to remove the dust. I did know one chap in the UK years ago who used to show plants and he liked to water from below in order to keep all the shed areole hair on the top of the plant to keep it looking woolly on top. He was incensed when another collector just gave it a blow and removed all the loose hair! Of course if you don't grow in the still air of a greenhouse the wind and rain will naturally remove the loose stuff for you anyway.

Our plants are pretty tough, so no need to mollycoddle them too much. I do find it helpful to look at the pots first thing in the morning before the sun gets on them to tell if they need watering however since the water rises to the surface of the pot overnight and you can see if it is still damp. When the sun comes out the top surface often dries fairly quickly and they look as though they need water, though may still be wet below.

As always, whatever works for you!

[Ivan C]

Another thing to consider is mold or mildew. Whether it is in the morning or evening, if moisture stays too long it can promote unwanted bacteria to form. Generally, it is suggested to water in the early mornings so the soil has a chance to dry during the day.

[peterb]

If you are watering at a time when there is danger of mold or bacteria or other pathogens to form, then you are watering at the wrong time of year, not the wrong time of day.

peterb

[*Barracuda_52*]

Where i live and due to night temps fluctuating so much i tend to water by no later than mid day so the pots are drier by the time night sets in and i always water on sunny days as gloomy rainy days are cooler.

[Steve Johnson]

Another thing to consider is mold or mildew. Whether it is in the morning or evening, if moisture stays too long it can promote unwanted bacteria to form. Generally, it is suggested to water in the early mornings so the soil has a chance to dry during the day.

Totally agree with peterb. Besides, my pots are in pumice/DG with gravel top dressing, so there wouldn't be issues with mold or mildew anyway.

Many thanks to y'all for settling the question. And yes, Dave -- it's part of my cactus education to differentiate between the appropriate details going into good cultivation and needless mollycoddling.

[iann]

impossible due to the focal length of the "lens" created by a beaded drop of water

It is perfectly possible for a lens to focus the sun within itself, let alone at the surface it is resting on, and I have photographs showing it actually happening with water droplets. I won't post them this time because I've shown it so often you'll all get bored None of which proves anything one way or the other, except that there are a lot of stupid people on the internet

I water when it rains. Discuss

[DaveW]

Drops focusing on the surface though does not discount damage being prevented by heat being removed by convection within the water drop and evaporative cooling though Ian? An easy scientific way to prove it is to put water drops on ones skin and hold your hand up to the sun and see if you can get them to burn, beats all theory and old wives tales!

[iann]

Drops focusing on the surface though does not discount damage being prevented by heat being removed by convection within the water drop and evaporative cooling though Ian? An easy scientific way to prove it is to put water drops on ones skin and hold your hand up to the sun and see if you can get them to burn, beats all theory and old wives tales!

You have to stand very still at just the right angle for several hours. I tried and got cramp in my arm

[DaveW]

Water would have evaporated long before that Ian so the "lens effect" would have disappeared and in the UK the sun have gone in a long time before!

[iann]

Water would have evaporated long before that Ian so the "lens effect" would have disappeared and in the UK the sun have gone in a long time before!

Water evaporates? Not in Manchester!

[Peterthecactusguy]

BTW as an aside, I have had no issues watering in the afternoons when it's 110 and humid outside during monsoon season. For plants in ground the water might evaporate slightly before the plant soaks it all up, but for plants in pots I don't see it mattering much really. I mainly make sure for my potted plants that it's not directly sunny on them when I do water. I guess this is done out of habit to prevent evaporation, even tho, in this case it doesn't matter at all.

[Steve Johnson]

Thanks for a great discussion here, everyone! I normally don't quote myself, although I'll bring my part of the thread full-circle from the post that started this:

My gut feeling is that watering in the morning may be better when overnights are on the cool side, then watering at night in Summer when nights tend to be warmer.

I wanted to test that assertion in case I fell for a myth. Looks like I did, and rather ironic since I busted an earlier myth about the roots of plants needing to "breathe" through porous clay. Although non-xerophytic plants may be able to get away with it in plain terracotta, I believe that porous clay is simply wrong for cacti and succulents over the long term. I don't like plastic pots for several reasons, so I've been waterproofing my terracotta to reduce evaporation through the pots as much as possible. Such being the case, I can now understand the reason why it really doesn't matter if we water during the day or at night. Hopefully I can pass along this bit of myth-busting to others who might be able to use it.