What am I doing wrong with Rockwool?

Hey RIU,

I've been growing more and more stressed over the last 2 weeks and need some help. I have grown quite successfully outdoors in the past, trying my first indoor setup now with hempy buckets, starting seeds in rockwool. I got 5 good feminized seeds from Nirvana. Heres whats been going down. The rockwool cubes I got from my local hydro shop say to dip in Ph adjusted solution for 10 seconds (specifically says no more, before anyone tells me I'm supposed to soak em). I did that. The first two seeds I tried I germinated w/ paper towels, the taproot popped out on both nice and healthy and I stuck em carefully in some cubes that i had hydrated. After no green popping out after a while i ripped the cube a little bit open to get a look and found they hadn't grown at all since i put them in. I realized I had put them in upside down and I guess they weren't able to fix themselves (as seeds usually should) and eventually they died. Round two, I used two more seeds, this time without germinating because I fucked it up last time and the successful grows I had in the past were from just straight up planting seeds (although in soil). One of them popped out green pretty quickly but then stopped growing completely. I couldnt figure out why. By today, the tiny little stem it had was browning and the plant was sagged over. I opened the cube to find the root was ungrown - taproot length. The other seed has germinated in its cube and has a tiny taproot, and I'm trying to decide whether to leave it in the cube or figure something else out. It almost seems like the roots are unable to penetrate the rockwool or something is keeping the them from growing once in contact with it. I've had 3 good seeds that I paid good money for go to waste already and one on the line, can anyone give me any idea as to what the hell I'm doing wrong here?

Thanks a lot in advance,

Japhy

Are you keeping the cubes moist? Not soaking wet but thoroughly damp?

I use rockwool that has been cubed into 1cm x 1cm cubes in a silo cup.

what are kind of water are you using RO, tap, distilled, etc? and whats your ph?

Fill them with 4-5x their weight in water. Thats properly moist. Call it an anal way, but I get roots out the bottom in less than 4 days if I make sure to saturate them properly. And dont take the plastic off the cube, this helps evaporation happen faster.

A 40mm grodan cube will weigh about 5g dry. Properly moist about 25g. Usually I stick the bottom of the cube in the nutrient solution for a quick second and then pull it out and thats enough, if not a tiny bit more(30g)

This helped me out the most starting in RW, now I have 100% success rate. Before I was like you, coming into a room to see my plants drooped over from lack of water cause the cubes dried out too quickly.

Get a humidome for them, they really need it for the first week to get enough humidity to root.

I give them about .1EC of nutrient solution as seedlings. People argue about this all the time saying the plant has stored energy, but i've never killed anything giving it that small of a dose.

dont use rockwool. problem solved. i stopped a long time ago and went back to using jiffy pucks, and i still pop them in aero when ready, jiffy and all.

Rockwool is great I didn't think you could fuck up germing in them lol. I drop some seeds in a shit glass of water over night. I dip the rockwool in Luke warm water then I poke a tiny hold barely 1/4 in deep drop the seed in, tear off a thin piece of rockwool and barely cover it and the next day they are sprouted up with leaves on them already... Try covering them with a plastic back and keep the humidity in..it helps a lot. Good luck

I'm using tap water. My tap water is hard (minerals in it, usually calcium and magnesium) if that might be a problem? and I Ph the water to around 6. firsttimeARE i do basically exactly what you say, dip the bottom in briefly and let it soak up water (except no nutrients, just Phed water) and then I've been putting a clear glass jar over them to keep it humid plus something small holding up one side of the jar a little for a tiny bit of air exchange. I was actually getting worried that they were TOO wet (rotwool) and was letting them sit uncovered for some periods of time and rehydrating with more Phed water as needed.

No, tap water is great for seeds lots of food. I have never used rockwool I always here about peoples problems with clones not rooting and killing seeds, but I just use promix and have no problems at all.

superstoner1 said:

dont use rockwool. problem solved. i stopped a long time ago and went back to using jiffy pucks, and i still pop them in aero when ready, jiffy and all.

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^^^^^^^listen to what this guy is saying^^^^^^^^

bowlfullofbliss said:

^^^^^^^listen to what this guy is saying^^^^^^^^

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Nothing wrong with rockwool, obviously the OP has some issues but I dont think the rockwool is the issue.

I would also suspect that there is an underlying problem; could be temperature, and whatever it is if not fixed will kill the others whether placed in jiffy cubes, rockwool or soil.

regards,

japhy said:

I got from my local hydro shop say to dip in Ph adjusted solution for 10 seconds (specifically says no more, before anyone tells me I'm supposed to soak em).

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No one else noticed this?

I mean, I know he tried to preemptively defend against it but...............

Dude, rockwool is inherently high in pH @ ~8.0 or even higher.

Whoever told you to only soak them for 10 minutes told you *wrong*.

24 hour soak in 5.5 pH or else this happens EXACTLY:

I opened the cube to find the root was ungrown - taproot length.

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That's literally what happens when they run into that wall of 8.0 pH rock fibers.

I agree a 24 soak is the best thing. I used germ'd seeds and when I put them into the rock wool I put a little moistened (non-fert) potting soil in the hole add the germ'd seed and cover with a little more potting soil. Never had a failure and get roots out the bottom in just a couple days. Right or wrong it works for me.

The answer is lack of water. And that will happen quicker with jiffy pots.

24 hr soak is hogwash. I've soaked for like 5 minutes in 5.5 PH water and the plants survived. Wrong PH isn't going to kill plants that aren't absorbing nutrients yet. Sure if you left a plant out of range to absorb nutrients it will die eventually. You would see classic N def. first though such as yellowing of the leaves and eventually necrosis of the leaves.

i soak my rockwool cubes for 10-15 minutes in phd water. keep em moist. i dont think ill go back to jiffy pellets as long as rockwool is around.