What is the best way to water seedlings?

I weigh my seedlings so I know exactly how much they're drinking and when they need watering. I start in 4" pots and fully saturate the soil when they go in. This way I know what the 'full' weight is. I'm using FFHF soil, and I know the 'empty' weight is about 1/2 the full weight. So, if it's 300g full I estimate 150g for empty.

Every day I weigh the pot. The difference between yesterday's weight and today's weight is roughly how much the seedling drank (minus evaporation - see diff below). When they are under 50% full (see %Wet below), I'll give them 30-40ml around the outside of the pot. When they are < 25%, I'll water fully. As soon as they can drain the entire pot in 48 hours I uppot.

Here's an example of my seedling tracker, showing how I track the weight and when I water.
Gaby Tracker.png


Using this system I can usually top above the 4th node by day# 20 and get quite a bit of LST done before the auto starts flowering. I'm averaging well over 8oz/auto, check out my Vivosun Auto Oasis thread for more info. Here is a sample google sheets if you want to play around.
 
seaofgreen18 said:
If you notice in the top pic the seedling on the left has a darker brown stem @ the rooter got to be careful of stem rot the one in the dry rooter is more clean looking that's what you want the darker stem usually says to much water and issues could be coming! ✌️
Click to expand...

A lot of my seedlings had dark stems as well, I was wondering about that. Problem is the seedlings are growing out in the bush and get hammered by the rain so over watering is unavoidable, and the starter soil has water retention properties. All good now though, it's been sunny last few days.
 
LKABudMan said:
I weigh my seedlings so I know exactly how much they're drinking and when they need watering. I start in 4" pots and fully saturate the soil when they go in. This way I know what the 'full' weight is. I'm using FFHF soil, and I know the 'empty' weight is about 1/2 the full weight. So, if it's 300g full I estimate 150g for empty.

Every day I weigh the pot. The difference between yesterday's weight and today's weight is roughly how much the seedling drank (minus evaporation - see diff below). When they are under 50% full (see %Wet below), I'll give them 30-40ml around the outside of the pot. When they are < 25%, I'll water fully. As soon as they can drain the entire pot in 48 hours I uppot.

Here's an example of my seedling tracker, showing how I track the weight and when I water.
Gaby Tracker.png


Using this system I can usually top above the 4th node by day# 20 and get quite a bit of LST done before the auto starts flowering. I'm averaging well over 8oz/auto, check out my Vivosun Auto Oasis thread for more info. Here is a sample google sheets if you want to play around.
Click to expand...
8oz autos is impressive, you look like you train em pretty hard. Thanks for the sample sheet, I will have a little play around.
 
I use the pot weight technique LKABudMan described when they are babies (4" square pots) and early veg (6" round pots). I found a 10kg digital scale on eBay for $10 that works great for the purpose. After that they go into 4-gallon SIPs to finish so weighing no longer needed. The real mystery to me is how the chinese scale manufacturer makes a profit. Professional Ohaus scales cost hella more.
 
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