how much to water seedlings (newb)

[Ahzore bar]

@Guggsy that makes perfect sense.. I'll see if i can get the temps down a bit. Thanks

[Ahzore bar]

@brock1 i was worried being in the finals when they were so small there would be loads of excess water not being used in the pot? Or is being at field capacity pretty safe in terms of root rot etc

 

[brock1]

Just now, Ahzore bar said:

@brock1 i was worried being in the finals when they were so small there would be loads of excess water not being used in the pot? Or is being at field capacity pretty safe in terms of root rot etc

 

Field capacity is at the point after watering. Root rot isn't common with cannabis. You have a much higher risk of damping off bit this is mostly going to happen if your drip trays are sat in water. Your soil is like a sponge & will leach the water up from the drip tray. Once you empty the drip tray gravity take over & pulls the water downwards. Just like a wet sponge it will dry out at the top first while the bottom is still damp enough. What it also dose is draws oxygen down into the soil with each drying out. So your not going to be at field capacity for long even without the plants drinking the water. I water around every 3 day's from start to finish at field capacity. 

[Ahzore bar]

@brock1 awesome, thanks for the advice. Looks like the girls are getting a good drink tonight!

Edited July 29, 2023 by Ahzore bar

[Ahzore bar]

Right, so after taking @brock1 advice i decided to do an experiment.

I weighed both my pots. One comining in at 2.6kg and the other 2.7kg +- 20g. I then proceeded to bottom fill the 2.7kg plant to field capacity. After approximately 2hrs the plant stopped taking water in but the top 3 inches of the pot was still dry.. probably because of how dry the soil was initially and struggling with the capillary action (also fabric pots so not sure if this makes a difference). I then topped watered the plant to get the remaining soil moist. In total i gave the plant 4 litres of water. There was bit of run off(not great as nutes in soil being flushed away) and remaining water left in the catch tray from the bottom fill but its my first time and i needed to learn. Once settled i weighed the pot again and it was 2.6kg heavier. So in total the soil had taken its own weight in water. 2.6kg = 2.7kg - 100g for the pot. I would be happy to say that this is at field capacity. The soil is damp/moist not wet and if you grab a small handful and give it a good sqeeze a few drops of water come out.

So for anyone wondering how much water to give. If you can weigh the amount of soil in the pot then give the same amount of water. 1g = 1ml so 2.6kg = 2.6 litres.

To confirm this i then slowly watered my second plant using the info i had got from the first pot and sucess!. I gave the plant 2.5 litres of water and no run off just a damp mark on the catch tray below the pot.

The plus is i now also have my dry weights and field capacity weights so i can water appropriately when the plants are almost dry.

Fyi im using cann pro soil so i imagine this would be dependent on soil type and how dry intially it is. But thought it may be a good starting point with anyone else concerned about how much water the plant/ soil needs to retain and help figure out a watering schedule.

Also checked the plant this morning and looks as happy as a pig in sh!t

So thanks again @brock1the advice was invaluable

[5Lip]

Just now, Ahzore bar said:

In total i gave the plant 4 litres of water.

IMO that's a lot of water so I'd definitely leave them be for a while

[Ahzore bar]

@5Lip yeah i agree, all a learning curve. It took in 2.6 litres. Alot of that excess water was sat in the catch tray the pot was sitting in from bottom filling. But yeah i will just be watering based on weight now unless the plant gives any signals. 

[brock1]

4 hours ago, 5Lip said:

IMO that's a lot of water so I'd definitely leave them be for a while

That true but is a lot of water to much water. The importance of feeding to field capacity is to soak the ground and remove any air thats in it. As the soil drains and drys out it sucks down oxygen into the voids that were filled with water. This is one of the main ways co2 gets down to the roots. Its important you let the soil dry out as much as your water it correctly. Theirs a number of tricks used to see if the soil needs saturating again. 

 

Check the weight you will get to understand how much lighter a pot is when it needs watering. Then their the move the pot and check for condensation if it pretty dry underneath the pot its ready to be watered. Then you got people who poke the point at the top to see if the doll underneath is damp. Not my thing that 1 really. 

 

But my point is the oxygen from that water to root is as important as the oxygen from the air to the root.