Jump to content
  • Sign Up

Oh No, fungus on the rockwool

Recommended Posts

Hey folks, my plants are going well... although i have noticed a little browning starting to take place at the roots, aswell as some kind of green (possibly fungus) forming on the rockwool. My plants are always in cooler conditions, have good airflow as i put them outside in the sun throughout the day, and under the lights at night time.


PH is 5.5

im using seasol, canna coco A & B at the moment, 2 x 10ml hand feeds per day


i think i chose to large a size of rockwool and i would have less chance of root rot etc if the rockwool wasnt in the picture.

Is it to late to remove the rockwool? how delicate are the roots at his stage of growth? and would it be possible to gently pull appart the rockwool, remove it, and have my plants direct in the clay pebbles and canna coco mix or should i wait for the roots to get thicker/stronger?


will the brown roots go away on their own?






here you can see the root tips getting thinner and turning brown





Link to comment
Share on other sites

Hey Blond,

Don't be stressing, its normal. The top of my rockwool goes green too until the plant gets big enough to block the light from the top of the cube then it dies.

If you are still concerned about it you can cover the top of the rockwool with a piece of panda plastic. Just slit the panda to the middle of the sheet then cut a small round hole at the end of the slit for the plant stem and BINGO one grow medium shroud. Algae needs 2 things light and moisture. Ya can't lose the moisture, your plant will ide. So block the light from the algae and it will die


Hope it helps



EDIT: +1 V(below) Knarfman is correct roots hate light. With my setup everything is black, pots = black, tubing = Black, tubs (and lids) = Black. I have seen another blokes setup. He used a clear white tub on wheels as his nutrient heart. The whole contents turned green and slimy. He covered the whole thing in gaffa tape, including the lid to stop the light getting to the fluid, it worked but not as well as having all black.

Edited by merl1n
Link to comment
Share on other sites

Totally agree don't stress. Mine get a bit of algae growing on them if I don't have enough clay pebbles covering them so if I see it I just wack a few more clay pebbles over the area to bloke the light and the algae dies off. bit of a shame really cause the green algae makes it look a  bit like a Bonsai. 


As for the roots...... ROOTS love the dark.  I notice that your pots are clear try wrapping something around the pots to keep the light out.

Edited by Knarfman
Link to comment
Share on other sites

oh crap, i didnt know the roots should be kept in the dark, thank-you so much for letting me know, it certainly expains alot. I also feel better knowing it doesnt mean the death of my plants :) i think i would struggle to paint the tubs black now without poisoning the plants so ill use a black garbage bag to cover them up for now. Thanks so much for the responses !!

Link to comment
Share on other sites

but out of curiosity would it be to damaging to attempt to remove the rockwool? i wont be using it for my next grow, as i find it holds to much fluid, and is preventing me from giving my plants their nutrients as i have to wait for it to dry out every 2 days.... but i noticed the medium which is just canna coco and clay pebbles allows "more flow" and drainage, so the medium is dry and ready for another feed within a day (under the rockwool) but ontop of the rockwool it never needs watering. has anyone else seen someone remove a plant from rockwool? if so how did they do it? just break away bits at a time?

Link to comment
Share on other sites

Unless you are friends with Captain Kirk and he lets you use the Transporter to beam your plants out I'm afraid your stuck with the Rockwool at this stage of your plants life.


From your pictures, looking at the roots coming out, if they were mine they would be in a bigger pot sitting nicely amongst the clay pellets. But that just may be me, this is only my third grow hydro as I have always grown outdoors before so maybe one of the more experienced members might give an opinion.



Link to comment
Share on other sites

Personally I use Rockwool as my starter medium. I use 4inch x 4inch x 4inch cubes. Once the plant is showing roots out through the bottom of the cube, I plant the whole cube and plant into my grow medium, which in my case is primarily perlite with a 4inch layer of clayballs in the bottom of the 50ltr pot. This allows for adequate drainage so the roots are not always soaking wet. Them being constantly wet can encourage root rot, which can kill your plant. Your plant has two types of roots, fluid roots and air roots. Too much fluid and your air roots will suffocate, to much air and you fluid roots will starve. Its a balancing act of sorts.
Both the perlite and clayballs MUST be washed before use. The dust from both acts like a grinding paste when it gets wet and is awfully harsh on water pumps. Also the  perlite compresses causing more dust which can smother your roots, this is why I use clayballs as a lower layer, they do not compress and they give the roots a space in which they can get air.

By attempting to now remove the plant from the rockwool you will do more harm than good. You need to allow the rockwool to dry out, almost completely and get it out of that clear plastic container IMHO



Link to comment
Share on other sites

blonde some rockwool u can easily pull apart but the more expensive rockwool is nice and compressed so it may be difficult to pull apart just leave it and plant the rockrool block 10mm below the top of your coco and u wont have any problems if the coco dries out before the rockwool the coco will just suck the moisture from the rockwool and vise versa this is why they make rockwool cubes for hydroponics and jiffy pellets for coco but i find i get 100% clone success cloning in rockwool 40x40mm cubes than planting those clones into coco works great


as for pulling apart your rockwool u can pull thin layers off the sides untill u hit the roots than stop but it'll just be a waste of time plant that sucker in the coco and watch it grow,



Link to comment
Share on other sites

I took a chance and peeled the bulk of the rockwool away from the root section. On one of the plants i do believe i damaged some of the roots, but for the others i was extra careful.


Now that the "over watered" symptoms have cleared since removing majority of the rockwool, i now seem to be facing the opposite issue – under watering lol, but im unsure if its due to the shock of removing excess rockwool and having the plants planted directly into clay pebbles and canna coco. I see there has been lots of root growth since removing the rockwool, but in terms of my plants health, they arent looking to good... but hey, what did i expect? i disturbed the roots, so i was aware that plant death was a risk, but i wanted more control over the nutrients and feeding, and as im using LED lights, CFL and sunlight, because of the heat being minimal it wasnt evaporating much water from the rockwool cubes, plus the area where the rockwool joined with the canna coco and clay pebbles was getting slimy, and i was unable to flush them, so im kind of glad i removed the rockwool, but now im facing other probs. Since transplanting I assumed I was facing nutrient burn as the tips turned brown towards the lower plant, so I have been watering with just water for one day. Last night I fed them nutrients

  • 1ml A & B per 500ml water

  • + 0.5ml seasol,

  • PP 129,000

  • PH 5.4

switched from LED to CFL again last night, I see new growth has taken place, but still the illness is fairly clear.

Iv tried diagnosing each plant according to articles but iv become confused as each plant has a different symptom.... is it possible each plant is suffering from a different deficiency or problem?


Ill start with my New York City diesel -

I initially spotted the yellowing and curling of the embryo leaves, with slight yellowing of the lower canopy tips. Now I see theres dark spots forming on the leaf tips only.





White Rhino

theres only very slight yellowing, but most notable is the disappearance of serrated edges of leaves. They also appear to be slightly dry, and warping in directions.






doesnt have the dark spots, doesnt have the warped leaf growth but has yellow, and curled under lower leaves with ash grey/brown dead tips - also appears as though leaves are dry



Has peeling stem, at 1st i couldnt see under the peeling, but now its come lose a little and i see the stem appears to be green under the peeling, but the embryo leaves are partly dead, and the larger leaves have a "droop" which appear similar to overwatered plants. Plus the leaves are "cupping" - im not sure what its called, but the leaf edges are turning up. Also new teeny tiny growth is extra dark green and is distorted.


Purple Power

I see slight purple of the stem but as the name is purple power im not to worried at this point, however, im unsure if its viewable in the photo but the top leaves appear to have tiny brown spots randomly on the leaf.


So it appears i have quiet a wide range of issues lol

i posted pics of each plant but exceeded the number of photos allowed.


so far iv learn (but may not be correct, so any input is appreciated)

** nutrient burn affects the tips only, slowly working its way up with a yellowing colour

** brown tiny spots all over the leaf = calcium deficiency

** Slightly Larger brown like patches or spots = magnese deficiency

** Darker twisted new leaf growth = copper deficiency

** Purplish patches = Phosphorus deficiency

** Leaves curling up in cupping = heat stress

** yellowing = iron deficiencies

** Drooping = Overwatering or Underwatering

** yellowing between leaf vein – magnesium, or magnese defficient

** lower leaves turning yellow and dropping off = nutrient burn or nitrogen deficiencies

** leaf tips turning downwards = Nitrogen toxity




nothing mentioned for leaves losing serrated edges?

Im unsure how my plants would have any heat stress as they are never put in overly warm conditions. The warmest they have been in is outside in sunlight, which is warmer than the grow tent, so the leaves curling upwards also has me stumped.


im guessing ill start with some Cal mag?

in regards to Boron, is that available on its own?

Link to comment
Share on other sites

Hey Blond,

OK let's start with some simple things. The little plant you have is a baby. Babies need to be nurtured, not beaten into submission. GENTLE!!!

Babies need more rest(recuperation time) than grownups, allow her to recuperate. Most changes you make take at least a couple of weeks to show. By changing everything all at once the shock is huge, so no wonder she's lookin a bit yellow.

Rather than boosting this and then boosting that, use a FULLY balanced food source. Me personally, I use a one part nute Made by Flairform here in Oz. Its balanced and being one part there is no mixing. I have used the same one part for the last 10+yrs, it is simple and it works. Why complicate things more. I use the KISS theory, KEEP IT SIMPLE STUPID. The less things there are for me to stuff up, the better. Water, nute, pH up, pH down, that's all I use. Why? Cos it works. And I can't cock it up and if I do, I can easily work back to work out what I did wrong. "DOH. Don't do that again" And learn.

Bl0nd, go have a cone and R E L A X. You can over love a plant and kill it with kindness.


I use a balanced one part nute mix. Some people think stronger nute mix will make the plant stronger. It doesn't. A stronger mix will burn. I have found for my setup 'Most' recommended dosage charts are too strong, Ive reduced my mixes by over 500ppm for a grown up plant and at the age that your plant is I reduce it again. Once its doing nicely, going some nice deep green shoots, then I 'up' the ppm but still probably 200ppm less than recommended dosage by the manufacturers.

Balance your pH. This is very important. Certain nutes get 'locked out' if the pH is too high or too low. There is a chart in Cannaversity that shows this. Go have a look.


My advice. Go buy some one part nute, make a mix, adjust your pH and.................RELAX!!!!! lol



  • Upvote 3
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using the community in any way you agree to our Terms of Use and We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.