Rockwool Soak. Need Help.

Discussion in 'Nutrients' started by uninc4life2010, Mar 27, 2011.


    uninc4life2010 Member


    I an new to growing, and I was going to start some femenized Jack Herer and Cheese From Greenhouse seeds in 2" Rockwool cubes. I will later be planting in Pure coco, so I decided to go with the CANNA line of Nutes. COCO A+B, Pk 13 14 and Rhizotonic.
    Anyways, I was a little unsure of the proper rockwool soak, but here was what I was planning on using. I was planning on mixing 1ml/gal each of Canna Coco A+B and 1 ml/gal of Rhizotonic in a 1-2 gal mixture. Then pH to 5.5, let cubes soak overnight, then plant the germinated seeds in the rockwool cubes, place in vented humidity dome under florescent lighting, and watch the magic happen.

    Ok, I know that COCO A+B is coco specific, but I don't think that it will make a huge difference using it in a diluted amount in rockwool. I also know that rhizotonic is only for plants that already have roots, but my reasoning is that it will be beneficial after a week or so once the plant has developed some roots.

    I just want to know if this will be safe and effective for new seedlings. If not, would it just be better to pH to 5.5 soak the cubes over night, and leave out the roots completely?

    Any input would be greatly appreciated!

    High74 Active Member

    The trick with rockwool is you never completely soak the whole cube just the 75 % down. Never soak the whole cube. And never let the nutes reach the top of the cube

    The next thing when working with rockwool is when first getting the roots going its best to shake off excess water.

    Keep in mind you want a 50% to 50 % water to air ratio.

    uninc4life2010 Member

    Thanks for the response, but that doesn't really answer any of my questions. Also, people submerge their cubes for a full 24 hours, so the part about not soaking the whole cube seems a little strange. The good ratio of air should already exist even if the cube is totally doused, since the material is already so fiberous and airy. Atleast thats what I have been told.

    High74 Active Member

    do what you do, but im telling you I have been using grodan roclwool for over ten years and the best way is to not soak the whole cube and to never let the top 25 % of the cube get wet. Good luck with it bro

    d7b Active Member

    I'll answer you some of the questions as although I am a sprouting demon in soil, I am a newbie at rockwool cube propagation .

    Well, not entirely. I used to always just washed them for ten seconds under the tap, jam in the seed in any direction (no soaking or moist cloth method) and put them in a tray with dome on my heat mat. I never touched the set up at all as I have the dome sealed and it never ran out of moister until the first set of leaves came out. Very simple and effective.

    This time around however, I am doing it slightly differently.

    Not that I think it matters that much, I will PH balance my cubes and soak them to 5..5 -.5.6 or as close as possible. Most people on the web agree 24 hours is overkill, but instead of my 20 second flush in PH 7.5 tap water jobby, I am currently soaking them in a litre of 5.6PH water with roughly .3ML of %35 Hydrogen peroxide (which i normally use in my water when sprouting in that method).

    Apparently, although functional, I have been reading that pre sprouting seeds outside of their main medium (soaking / moist paper towel method) isn't ideal for growth so I am going to avoid this method this time around. PH'ed Rockwool cubes straight in the dark warm environment. I know it works as well as in soil, but soaking seeds in H202 (35%) seriously makes my seeds pop over night. Its brilliant and fast.

    I have never pre soaked any nutrients in rockwool or soil and personally think its a bad idea. It might provide a minimal advantage after the seed sprouts, but you have eyes dont you? As soon as you see the shoot consider feeding the sprout at that stage, rather than when it is feeding off its own essential minerals.

    Even in my old style of barely washed chinese ghetto sprouting they were happy and healthy so I would stick with under doing it.

    I have also studied into the fact that high humidity is also not essential for sprouting seedlings and a decent amount of air exchange is beneficial for the seeds success as well. Certainly has never effected my seeds, but I will open all my holes in the humidity dome this time around to see if I notice a difference. When sprouting in soil under the CFLs, I never have a dome ever. I think my current RH% of 40% in my room will be fine (Hey...3 X 4 week old seedlings and a rooted clone are looking sweet with that same humidity as well). I will still cover them to maybe boost the RH to about 60%, simply to reduce the amount of misting I have to do (Im a lazy man).

    I am a COCO grower as well! The best shit ever. I used CANNA VEGA and FLORES last cycle with cannazym last time and it was amazing (The chillis and the tomatoes loved it as well!) . Brilliant result even though half my plants were soil and the other half coco drawing from the same reservoir! However, as you, I bought COCO A & B and Rhizotonic for this cycle as well and am keen to see how much of a difference it actually makes for the medium it's designed for. If it makes a big difference it will reinforce why coco is so popular...

    I will not be feeding with coco / rhizo combo in my mister spray bottle until I see at least one set of real leaves. Usually 1 week and a half in I will feed ( 300PPM or 0.4 EC roughly.) , and that is at earliest. I have my cubes in little black cups and just wait till I see the tap root and a few more out the bottom and spray the bottom of the cube as a previous post suggested, not the whole thing. I also mist the inside of the humidifier with normal water, but very lightly.

    in short: PH your cubes and squish em out, dont nute them. Keep it simple
    Tim Brittain

    Tim Brittain Member

    I can' beliee the total bollox on here no wonder there is so much shit weed about lol
    cat of curiosity

    cat of curiosity Well-Known Member

    i can't believe you bumped a 7 year old thread and feel you're superior... to anyone...

    but that's just me...
    Tim Brittain

    Tim Brittain Member

    Tim Brittain

    Tim Brittain Member

    Sorry twat

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