MrStinkyanswered grow question 3 years ago Massice post coming - hopefully it helps:
I call this 'The Stinky Method' 🤣
I was sick of not finding accurate watering information, so I'm putting together a side project for myself to figure out average waterings in soil, all the below from my current grow:
11L GroNest fabric pots
Autos
Temps 20oC dark - 26oC light on
Humidity - hard to get mine lower than 60% so I followed VPD charts.
Get a small hand sprayer for early weeks and a big sprayer for later on - prevents you watering too fast and lets you soak the whole top of the pot.
Watering in week 1 tip: Get a 05.L plastic cup that is be enough to just cover the plants over like a helmet so you dont spray the leaves - I burned my first plant doing that. Do this every day until the plant no longer fits under the cup.
Each watering in seedling week should be dry in 24hrs and keep your humidity like 70-90%
Week 1 - 100ml per day, increased 20ml per day, sprayed across the surface of the soil and 5-10ml at the bottom of the stem in a gentle trickle every day.
The trickle at the base to give the plants tiny root some water straight away. The spray all across the top to soak into the top few cm of the soil to let the spreader roots rush across the top of the pot to chase the water, you have smartpots so it makes sense to encourage lateral growth ASAP
Week 2 - 250ml per day increasing 10-20ml per day (plant should be too big to fit under cup this week so just spray carefully) and a couple of squirts at the bottom of the stem
Week 3 - 350ml per day
Week 3 mid week - 1 x 1L watering of the whole pot (I am organics) - let half of it dry (weight pot before and after) and then a 250ml watering on top once half of the 1L is gone.
Week 4 - up to 500ml per day and rising - about 100ml directly at base if stem every watering now - (you could even start a 1L every few days now and forget the top waterings.)
Week4 mid week - 1x 1L water / 2 days dry (almost saturated)
Week 5 - 750ml per day and rising steadily with a 1L - 1.5L watering once a week so the bottom of the pot is still getting wet and the lowest roots keep working and dont dry out.
Continue increasing until they reach max water intake per 24hrs
Slow your watering when they are no longer drinking a 2 day watering in 4 days as you are approaching harvest.
With the 1L+ feeds, do it slowly on a young plant in 2 x 500ml sessions about 1 hour apart to allow the top of the medium to absorb water, and then the 2nd watering for the water to flow to the lower substrate.
When soil gets too dry it becomes hydrophobic and the water will just follow the path of least resistance and drain out of the pot but keepnit wet and you are drowning the roots.
Do not use pure RO / demineralised water without calmag as you cant pH it and it strips nutrients, if you are using that kinda water, always add calmag to about 150-250ppm
The reason for the 1L+ feeds is Im on dry organics and 1-2L almost gives me run off, I can just feel moisture under the pots (fabric, 11L Gronest) so I'm not watering to runoff, but helping the roots lower down in the pot chase a nice big drink. It am hoping it also allows me to build into a constant wet / dry cycle, eventually I hope the pot should synchronize and need a full watering every day or two.
*Update* - it did work. The biggest was drinking 1.5L every 2 days and the whole pot was going wet / dry every 2 days at peak water intake.
I try to imagine watering the plant like spring rain showers man, and a bigger plant will definitely suck up more rainwater than a smaller plant but a rain shower isnt a waterfall.
It helps to know the weight if your pots wet and dry for sure, put them on scales if you need to - I did / do, thats how I know how much my girls are drinking on a daily basis 😅
I also 'roughly' follow VPD charts to allow for maximum transpiration, my temps are also sweet at 20oC-26/27oC
The liquid amounts were kinda based on fractions of the pot too, my 1L feeds are like 10% of the pot, increase or decrease your waterings in proportion based on the size of the pot in the early days, I dont water to runoff of more than say 40ml cause I'm not synthetic nutrients and want to keep my microbes in the pot.
Disclaimer: the above post is PURE 100% 2nd-grow bro-science, but it's definitely F worked man and I've had no signs of over watering yet - if you can see the difference between my first and second diary you might be shocked...I am!
I know that is a lot of reading, and that watering is not an exact science, but, bro-science or not, I think that is the most comprehensive watering guide that I have seen and I will be following it closely for future grows.