Growing in Rockwool--advice?

I'm trying to grow a couple of plants in Rockwool, and they were doing okay, then they took a turn for the worst and became very wilted and yellow.

I gave them more nuts, and they didn't look much better.

I was just wondering what experiences people have had with Rockwool, and what they learned works the best, etc.

(The 'Dos' and the 'Donts'--that kind of things

I really appreciate any advice!

Bump it up

Could be pH related being as its rockwool. My advice would be to find an easier medium to work with.

What makes the Rockwool so hard? I like the fact they're in easy to handle cubes--that's why I'm trying to make it work

Is it that feeding them is so difficult? (Like the ph?)

Growing in rockwool requires at least 2 feedings a day with accuracy used in aeroponics. For a newbie grower its way too frustrating. Plus, it has no benefit over coco that I know of. (well, coco has some K that breaks down so its not ENTIRELY inhert like rockwool, but i don't count it as a con)

The rockwool cubes only work for a week or two, then you need to plant in a pot of rockwool or use a ebb and flow table. in any case the roots need a place to go.

Do you have to feed them twice a day, even if the cube us moist to the touch?

That would definitely explain why they look so wilted...

Yes, you do.

this goes along with the OP's question. I just started a seed in rockwool after i realized i was out of soil. What or when exactly can or do i transplant it. Rockwool seems very hard to propagate in IMO. I Ph my water but ... should i be feeding this seedling at any point?? I was just using the rockwool as the starting medium.

I have almost a decade and a half of experience using rockwool. I think it is quite easy to use, although I do not start seeds in it. I do not water until the rockwool is getting light which might be days apart. The only problems I've ever had was when I watered it too much and root rot sets in. This is just my experience, your mileage may vary....

to the above post and the quoted i have started many seedlings in rockwool sometimes without even phing the water but that is because i know the water where i live is fairly good because i have tested it before but things change as we all know. Best way that worked for me was the standard rough up the seed a bit and i soaked them in phed water and poped em in. They usually come out in 3-4 days if they were meant to come out at all. I've never taken a seed out of rockwool that has sat in it for a month and not come out with it being cracked and a tap root shot like i have in the many other methods i have tried. But then again you cant go wrong with nature either for germing seeds. Pop em in soil works great too. i usually start feeding after i have taken the original 1x1 and transplanted it then just light feedings.


I love rockwool if your smart and think a little bit its not that hard to use at all. As hum said your mileage may vary but for me it works great.

ataxia said:

this goes along with the OP's question. I just started a seed in rockwool after i realized i was out of soil. What or when exactly can or do i transplant it. Rockwool seems very hard to propagate in IMO. I Ph my water but ... should i be feeding this seedling at any point?? I was just using the rockwool as the starting medium.

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Kaptain Kron said:

to the above post and the quoted i have started many seedlings in rockwool sometimes without even phing the water but that is because i know the water where i live is fairly good because i have tested it before but things change as we all know. Best way that worked for me was the standard rough up the seed a bit and i soaked them in phed water and poped em in. They usually come out in 3-4 days if they were meant to come out at all. I've never taken a seed out of rockwool that has sat in it for a month and not come out with it being cracked and a tap root shot like i have in the many other methods i have tried. But then again you cant go wrong with nature either for germing seeds. Pop em in soil works great too. i usually start feeding after i have taken the original 1x1 and transplanted it then just light feedings.


I love rockwool if your smart and think a little bit its not that hard to use at all. As hum said your mileage may vary but for me it works great.

Click to expand...

thanks for the reply ... I know rockwool is an inert medium so i wasn't sure about how long the seedling will stay in the rockwool without the nutes. I germed them in paper towel first then transplanted it into the rockwool. It's sprouted. the taproot as reached the bottom and it's off and running. I am curious though ... How long before i throw it into soil. I know i could do this at anytime but I'm used to starting in soil and letting the nutrients in the soil do their thing until it's time to feed. Rockwool contains no nutrients. that's what made me post the question about how long before feeding.
I'm sure it's easy as pie ... it's just a whole new thing for me. I have no idea what to expect.
Thanks again Kaptain

McFonz said:

Growing in rockwool requires at least 2 feedings a day with accuracy used in aeroponics. For a newbie grower its way too frustrating. Plus, it has no benefit over coco that I know of. (well, coco has some K that breaks down so its not ENTIRELY inhert like rockwool, but i don't count it as a con)

The rockwool cubes only work for a week or two, then you need to plant in a pot of rockwool or use a ebb and flow table. in any case the roots need a place to go.

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fuck me ... i could've just read this post before asking the question. Thanks again

i dont feed mine that much not until they are on the table then when they are about oh 8 to 12 inches i will put them on 2 times a day but if your going into soil which i have done check the thread in my sig for my desk grow right now. I prefer not to handle the seed at all after i rough em up and just drop em straight into a soaked cube i had best luck that way when they come out fully and have shot out they cotelydons and the first single leaf set i put em into soil or coco or whatever i happen to be using at the time. I had seeds die on me that i let come out in the paper towel and then i put em in the rockwool. So i just decided hands off let nature takes somewhat of its natural course at least at the start.

ataxia said:

thanks for the reply ... I know rockwool is an inert medium so i wasn't sure about how long the seedling will stay in the rockwool without the nutes.

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The seed has "built in" nutes. The first couple weeks, it uses its own supply then you need to start feeding it.

rockwool is good and all, but I always end up putting everything into hydroton anyway....so I switched to rapid rooter plugs and they rock. They are 100% organic and the root growth is awesome for the little seedlings.

McFonz said:

Growing in rockwool requires at least 2 feedings a day with accuracy used in aeroponics. For a newbie grower its way too frustrating. Plus, it has no benefit over coco that I know of. (well, coco has some K that breaks down so its not ENTIRELY inhert like rockwool, but i don't count it as a con)

The rockwool cubes only work for a week or two, then you need to plant in a pot of rockwool or use a ebb and flow table. in any case the roots need a place to go.

Click to expand...

I grow in 4" rockwool cubes on a flood and drain and if I were to follow this advice especially in the first 3-4 weeks, I would kill my roots and have wilting plants like the OP.

Hum215 said:

I have almost a decade and a half of experience using rockwool. I think it is quite easy to use, although I do not start seeds in it. I do not water until the rockwool is getting light which might be days apart. The only problems I've ever had was when I watered it too much and root rot sets in. This is just my experience, your mileage may vary....

Click to expand...

Exactly! My mileage is the same. It is too easy to overwater rockwool cubes. Let them get drier (lighter) but not completely, before waterings. I never had an UNDERwatering problem, even when I did get them drier at times.

what size cube are you using? what's your ph? please tell me so I can help(pics would help too) I use rock wool with great results

I too have had bad luck with rockwool. It's very hard to flush (if needed) and once placed in soil it acts as a sponge at the root ball. I had problems with nute burn and overfeeding because the nutes would pool in the rockwool like a sponge as oppossed to draining to the bottom and out with just soil. I have found that peet pucks work the best for me and just break appart in the soil shortly after transplant. I also had a problem with seedlings tap root going through the top and dying.

My 2 cents. Good luck bro!

DJ TEEREKS said:

I too have had bad luck with rockwool. It's very hard to flush (if needed) and once placed in soil it acts as a sponge at the root ball. I had problems with nute burn and overfeeding because the nutes would pool in the rockwool like a sponge as oppossed to draining to the bottom and out with just soil. I have found that peet pucks work the best for me and just break appart in the soil shortly after transplant. I also had a problem with seedlings tap root going through the top and dying.

My 2 cents. Good luck bro!

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rock wool is easier to flush than soil and as for seedling root dying you placed the plant too soon in the soil. You are suppose to see roots at the bottom before planting in soil. As for feeding you should wait until the cube feel light before watering until you see roots then you can start feeding them more.

Realstyles--what kind of watering system are you using? What is your nute schedule, and what kind of nutes and how much?

They look beautiful--I can't believe they're growing that nicely out of rockwool!