What are the pros and cons watering plants just before the lights go out?



A customer has a question and I hope we can get some opinions on it, thanks.

What are the pros and cons watering plants just before the lights go out


Its not recommended to water just before light out indoors more to prevent mold and root rot best to water two hours before lights out
While the plant is uptaking moisture from soil


@Countryboyjvd1971, my system is nearly fully automated. When low soil moisture level is detected, should I wait until lights ON to initiate watering, wait until the lights have been on for a while before watering? In other words, is there an optimal time during the day/night schedule to water?:writing_hand:
@neckNflu @Niala @Myfriendis410 @ReMoLu @bob31 @Rugar89


Its best to water just after light on if possible
But in the real world most of us will do what we need to lol i try not to water or feed at end of light cycle but occasionally will need to
If your automated then i would set it to water just as lights come on


Thanks @Countryboyjvd1971, it will be quite easy to program the system to initiate watering when the lights come on when low moisture has been detected at some point in the “day” or “night”.

It never occurred to me that watering should be done at a certain point in the day.
My watering system consists of a 10 gallon cistern which comes to room temperature between watering and the water is pH corrected just before it is time for water to flow (by pump) to the plants. Nutes are not automated, can’t afford all of the extra sensors and other equipment to automate that part.

My automation is not an effort to did-engage from the process, rather an effort to insure consistency, especially when I go out of town from time to time. :cowboy_hat_face:


That’s interesting @merlin44 you in pots ?
Id linke to check out the set up
That’s awesome your water auto phs :+1:
Tag me into your thread brother it would be easier then me looking for it lol


@Countryboyjvd1971, to me clear, I have determined how much pH Down is required to achieve desired pH (6.3 for now until soil gets into spec). I time an IV drip to deliver that much pH Down to the cistern an hour before watering starts. The system has not been put to the test because my grow in just 12 days since sprouting and I am watering manually while monitoring the automatic system to insure proper function. :writing_hand:


10-4 please tag me in buddy


Me too if you don’t mind. I’d like to check your system out.


The only issue I have with that is the cistern needs to discharge it’s entire contents when watering otherwise ph will be off. FYI


Indeed, I also will need to monitor and make adjustments as needed. Small price to pay for the overall convenience and peace of mind. Great observation! @Myfriendis410

What would be the consequences of adjusting the pH of the water one to three days before use? Will the pH be stable while sitting in the open topped cistern for that period of time?
@Countryboyjvd1971 @dbrn32 @Rugar89 @Niala @neckNflu @bob31


Ive actually wondered about that myself but have noticed that in the past when i had water say in a five gallon bucket in grow room that it would always slide away from where i phd it to earlier
So i stopped doing it and just ph when needed
You can go with a smaller res maybe depending on how plants you need to water and feed
Im foing to do a experiment when i get home ill
Ph five gallons a let it sit for a few day maybe three and retest see what happens ?


@Countryboyjvd1971, excellent. Please tag me in with your results. It may impact my design and to a greater extent the programming. :writing_hand::cowboy_hat_face:


Will do @merlin44
I actually have well water i have a ro fiter that i use
Last time i didnt have the ro filter
I had a three stage filter setup only
I have high ppm in my well water i wonder it that would also make a difference
So ill fill up to five gallon buckets
On just triple filtered and one using ro water
Maybe one of the the minerals in my well water cuased the ph to fluctuate? I will post my findings in a few days


I’m interested in how your system is able to detect that it needs to water…?
Is this set up for just one plant…?
When growing more then one plant they always seem to want to be watered at different times , just curious how your getting around that…?

:v: :sunglasses:


Try this experiment: ph a 5 gallon bucket and leave it stand. Repeat every day for the next several days and eventually you will have a stable ph at the value you want. It takes about 5 days with tap water. So it’s possible to produce a stable water supply but you’d need a good sized reservoir: actually 2.


Hey @peachfuzz, I am using a capacitive type moisture sensor. Initially will use two of them and either average to two values or use the dryer of the two, don’t know yet. Ultimately will have a sensor in each pot. May need to put solenoid valves on each plant’s water line, will wait and see how much and often the plants need water. That is the reason for running it manually, with the automation in place, so I can characterized the grow system and it’s requirements. Much to figure out, and may end up being a waste of time, although I hope not.


Excellent suggestion, @Myfriendis410. I will do that when the system is back together. Thanks.
My water is comes from a small, private water system. Light chlorination. The problem was that I have a water softener which adds sodium to the water as part of the softening process. I tapped into my water line before the softener and plumbed that line down to my grow room. The water pH is 7.2 - 7.5.


Ok i will do you think the ro water will be different from just tap ? @Myfriendis410
Good question @peachfuzz
@Hogmaster you should take a look at this set up


I’m sure that ph sensor is available, not sure cost is reasonable enough to justify though. If you can get a sensor would be piece of cake to automatically adjust.

I’m not familiar at all with programming them. But on ab you could do it handful of way. Just have xic from ph sensor in series with whatever sensor you have calling for water. Then create sub routine for ph adjustment logic. That should look something like a less than function activates a one shot on rise to ph up valve. A more than function sends one shot on rise to ph down valve. Then insert timer on function and air stone to circulate solution for however much time you figure to stabilize. If ph sensor is still not in range, repeat til it’s reading is in range. Then as long as other conditions are true, apply your correct solution to plants.