rockwool root rot

[BOBBY_G]

im stumped here. been using rockwool for over 20 years and have never seen this, its so well draining ive never seen lack of aeration

i got 6 clones from a local dispensary like 2-3 mos ago and they are not growing at all. they were skinny bottom clones (all they had of the strains i wanted) in 1" cubes so no big deal, ive nursed tons of stressed plants back from the edge over the years. they had some weak roots so i gave them the normal 1/2 strength nutes and moderate light and waited and waited and waited. finally got some fresh root growth on them so i popped them into some 4" cubes and kept up with the light feeding

thing is weeks and weeks later, one of the strains (ACDC) finally poked thru the bottom of the 4" cube with roots, the other (GG4) has yet to do so. GG4 is super tiny runty but green, the ACDCs were doing ok but have turned pale recently. in the same time right next to these under the same exact lights ive already gone thru 2 cycles of clones of my usual strain and the first are ready to flip already. vigorous A+ growth on those

the affected cubes smell mildewey i didnt think it was possible to overwater rockwool. ill try to dry it out but what can i do to treat the rootzone in these.

sure hoping i didnt bring root gnats or some other painful pest into my otherwise pristene garden.

I just mixed up 15 ml/gal of (10 year old) 35% peroxide (not sure if its even effective anymore). flushed the cubes and set them on top of other cubes and some cardboard in an attempt to dry them out a bit, then put a root heating mat underneath them to further encourage drying

any suggestions welcome

thanks

 

[bobtokes]

tried any rootzone nutes like rhyzotonic on them, i always put stubborn clones under a 600watter, kill or cure lol

 

[BOBBY_G]

yeah i went the opposite direction, dialing back the light for a bit till they perk up. the GGs are healthy looking but just slow and runty.

 

[todd86]

im stumped here. been using rockwool for over 20 years and have never seen this, its so well draining ive never seen lack of aeration

i got 6 clones from a local dispensary like 2-3 mos ago and they are not growing at all. they were skinny bottom clones (all they had of the strains i wanted) in 1" cubes so no big deal, ive nursed tons of stressed plants back from the edge over the years. they had some weak roots so i gave them the normal 1/2 strength nutes and moderate light and waited and waited and waited. finally got some fresh root growth on them so i popped them into some 4" cubes and kept up with the light feeding

thing is weeks and weeks later, one of the strains (ACDC) finally poked thru the bottom of the 4" cube with roots, the other (GG4) has yet to do so. GG4 is super tiny runty but green, the ACDCs were doing ok but have turned pale recently. in the same time right next to these under the same exact lights ive already gone thru 2 cycles of clones of my usual strain and the first are ready to flip already. vigorous A+ growth on those

the affected cubes smell mildewey i didnt think it was possible to overwater rockwool. ill try to dry it out but what can i do to treat the rootzone in these.

sure hoping i didnt bring root gnats or some other painful pest into my otherwise pristene garden.

I just mixed up 15 ml/gal of (10 year old) 35% peroxide (not sure if its even effective anymore). flushed the cubes and set them on top of other cubes and some cardboard in an attempt to dry them out a bit, then put a root heating mat underneath them to further encourage drying

any suggestions welcome

thanks

It certainly is very easy to over water in rockwool, infact rock wool is notoriously bad for this and only really suitable for NFT systems.

also check your PH run off, did you presoak them in PH 5.0 - 5.5 water before using,
rock wool is very alkaline due to the material they make it from, pre soaking in PH adjusted water is recommended if the factory hasn't already done it.

 

[BOBBY_G]

thanks for checking in

yes same as any other cube ive used in the last 20 years. something is up with the plants. as ive said ive cloned thru 3 cycles of my regular strain in that time with zero issues. ive never had to "force dry" rockwool, as even when its saturated (unless its submerged) it still holds a lot of air. im just trying to get them big enough to take my own cuts and start from scratch

 

[todd86]

thanks for checking in

yes same as any other cube ive used in the last 20 years. something is up with the plants. as ive said ive cloned thru 3 cycles of my regular strain in that time with zero issues. ive never had to "force dry" rockwool, as even when its saturated (unless its submerged) it still holds a lot of air. im just trying to get them big enough to take my own cuts and start from scratch

Plant the rock wool cube in potting mix is my advice.

 

[TubePot]

did you presoak them in PH 5.0 - 5.5 water before using,

Grodon recommends. no lower than 5.5.

 

[todd86]

Grodon recommends. no lower than 5.5.

Rock wool has a PH of around 8 Grodon probably pre-treats their cubes, even so there is no harm in using a PH of 5 as within 24 hours your PH will be about 6 due the the buffers in the rock wool if not higher.

Dont believe me, try it yourself with a Grodon cube, also a PH of 5 is not low enough to damage root physically , and with cuttings with no roots yet a lower PH actually speeds up rooting ever so slightly.

But yeah stick to 5.5 and you will be with in Grodons recommendations.

 

[TubePot]

What's funny is that when I used slabs in the 90's I soaked @ 6.0 and 1000 ppm for a min or two and in the tray they went. No internet to look up info.

Now that I look back so many mistakes were made and I was still getting great results, I can see now how better it could have been with just a few things.

There is so much info on the net today that it's hard to make a mistake.

 

[BOBBY_G]

its pretty hard to mess up ph with rockwool. there are no roots in 90% of the media when you transplant, and it quickly adjusts after just a few flushes with nute solution


FWIW girls are perking up. either the h202 or the root enzyme additive (slm150? or somesuch)

GG4 will be ready for cuts soon. acdc slower but im hopeful