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Rockwool into NFT question

I've done 1 grow before after I was given a cutting in a 4 inch cube in NFT, it worked, but I had problems. I failed recently after getting another cutting, which I believe wasn't  quite ready for my NFT gt205 tank. 


I now have seeds and want to check my process is right, I'm just germinating them in 2 inch rockwool cubes in a propagator. I soaked them in a solution of PH'd water with some seedling Biosis instand microbe tea. (recommended by the hydro shop man)  I have this dark at the moment. 


When they pop and show a leaf I understand I then put them under the light? and keep them in the propagator?

When the roots show out of the 2 inch, I drop them into the 4" rockwool cube. I understand that when the roots start to show out of the 4" cube I drop them into my NFT tank.

My question is, when and how to I feed them before dropping into the NFT?


Is it just a weak Hydro solution misted over them? Water the cubes?

When do I take the lid off the propagator?



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I wait until they crack after soaking in water or sealed in a humid container, soon as I see the tap root coming out, I make the hole big enough in the cube and gently put her in.


I'll keep them in a prop or sealed until they throw their seed shells but my veg room is higher RH so it's not an issue in or out for me, you might need the prop lid but they will harden up soon enough out of it! Just keep an eye on temps and humidity, you can kill them pretty quickly ramming light up them under that lid! (depending what light)


I pre soak my smaller cubes in just water and that is enough to get them up and rooted, you could use root stim if you wanted to but I don't add anything to my smaller cubes.


It all depends on the size they are on how much you can feed, get yourself some formulex, small bottle will do you! 4" cubes..You can get away with 5ml per litre or down to 2.5ml per litre but might show issues or even stretch at 2.5ml depending on your room,strain and how long they will sit in there.

Pre soak the cubes in made up solution, if the seeds are big and healthy throwing out leaves in the small cubes, pre soak the bigger cubes at 5ml per litre. To save you some hassle, pre soak the cubes at the right PH or around 6.0. Should get them used to it quicker if you are going straight into the tank.


Prop lid is different in every room, your conditions won't be the same as mine but I like to get mine off as soon as possible, 1st true set of leaves for me or soon as they throw the shell.

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I make my own rockwool cubes of various sizes.


Not planted a seed for ages in rockwool and come to think of it, even when I grew hydro I germinated the seeds in a small pot with soil and once rooted well, into a rockwool cube it would go.


Seedlings have no issues going from soil starter pots to rockwool. It is easier, no ph adjusting or worries about what feed the seedling gets. Water them and relax.


Seedlings are the cannabis plant at their most vulnerable. For me personally, I always seemed to lose more seedlings started in rockwool than soil. More lanky also. (stretch)


For the prices people pay, you want the best start possible for a seedling. For me, soil has too many advantages.


Like babies on the tit, seedlings in the soil is a similar thing. It just seems natural.


Once they get to six inches or so and four sets of leaf at a decent size, they will take to rockwool with ease.


One other tip, always use rockwool slabs in NFT small scale. You can tie the rockwool down so that it always stays on top of the matting. I have grown plants just on the matting but if that mat of roots tips over its a disaster.


Good luck.

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Posted (edited)

Thanks mydisplayname2000 but I've already stuck my seeds in the rockwool. I may consider the small soil plug into rockwool next time. Seems a little simpler.


However...... they're in the 1" rockwool cubes, soaked in the biosys tea stuff I was recommended. I think this is a root stimulator. In a propagator with high humidity of around 90% and temps around 25c, but covered and dark.

When they pop out and show a leaf, I should put this propagator under my LED grow light in my grow space? Once roots start to show out the 1" cube I drop them into my 4" rockwool cube that has soaked in a PH'D solution with the formulex I just bought. I have soft tap water, with an EC lower than 0.1.  So use 5ML of Formulex? Then once roots out the 4" rockwool cube, stick it in the NFT tank?


Does that sound right? I have a small stealth grow space, so won't be able to grow more than 2 plants. But from the failed last grow from cutting, I noticed humidity quite low. Around 25 - 40%.

I'm growing Heavyweight Fast & Vast Auto Autoflowering Feminised 

Edited by minigrower

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Posted (edited)

always different situations and pruducts etc work for different places and people etc m8, after soaking mine upto 24hrs i then put them between a pile of paper towels keeping damp till they end up with a 1cm tail or any tail really and then i prefer to use root riots for their ease and softness to push out thru and pop the seed off as ive had many seed/leave heads stick inside the smaller rockwool cubes, once in root riots i put straight into 4inch rockwool cubes and from there i can get them to about 2-3 week veg stage then when my wilmas are emptied and ready i can basically plant the 4inch cube in my grow medium wen my last grow is down and at that stage i sometimes only need to veg my plants in the system for about a week or 2 at most b4 right onto flowering m8, 


i used nft trays years ago and 1 major thing u need to do is get them into a 4inch cube and vegged for ages till theres many roots at bottom of cubes which are starting to grow sideways along the base so wen u put it on nft tray on the ur layer of fibreglass the roots are kind of trained for growing sideways along the tray as opposed to down in a pot if that helps m8 + i believe at ur stage just now u want ur humidity about 60% 


ps just noticed u were using autos and the date and be done by now bud, hope all went good lol

Edited by Stevieboy1

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