Trouble I don’t understand. Need advice.

This is my third try and I am at the end of my wits.
First time it took 3 weeks for the plants to start showing the sides of stalk rot.
I purchased another set from the same grower.
This time it took 4 days. Plants went from being healthy to rolled inward, ill and starting to show signs of the same rot (the area where stalk touch the cube would start showing roting areas)
I purchased third set from a different person. I planted them Monday night. Last night they were beautiful. I did some preventive action by drip a few drops of hydrogen peroxide right where the stalk touch the cube.
This morning they show first sign of illness.
See pic.
I grow in grodan cubes. Used Flora nova half straight with CalMag at 5.5 ph to soak cubes.
Oh and I washed the room with bleach, replaced fans, changed water filters (I use RO). What can it be? What can I use? Please help.
P.S. my ac broke before all those problems started happening. I fixed it and also washed the filter with some sort of industry liquid that comes in cans.
Since I use runoff water I water about a month for it to run through and then started collecting and using it.

My first thought would be a temp/light/humdity issue. As in too much light too soon, temps too low or high causing stem rot, humidity too low causing stress on not established cuttings, or too high humidity causing the rot. So maybe a little more info on those metrics will help shed some light.

Yes. Sorry.
Temp ranges between 77-79
Humidity 53
I have 4 400 hps lights about 6 feet away

Last thing I forgot to mentioned.
To do preventive maintenance I mixed 32 percent hydrogen with ro water (1 part HP 10 parts water). Didn’t check PH and dripped about 2 ml on lower stalk where it touches the cube.
This morning they are sick.

What's the rationale behind using HP? What am I missing? You might want to use a different media, to see if it is the strain or something you are doing.

HP is said to kill the bacteria that causes root/stalk rot. So instead of waiting for it, I decided to use a few drops preventatively.

Tough one. Throwing ideas out here, what about air circulation? Looking at the cubes, I see the liner pulled up a quarter inch or so above the rock wool creating a little 'pond' of still air around the base of the plant. Made me think about avocados. Avocado trees are SO sensitive to lack of 'air drainage' around their base that they are traditionally planted on hillsides. Maybe by providing more air circulation around the bases of your plants to increase O2? Could work as well or better than the peroxide.

Not enough air movement around the crown (where stalk meets media) of the plant combined with too wet rockwool.

Get a fan blowing across the crown immediately. Let those cubes dry out some before watering.

AloeRuss said:

HP is said to kill the bacteria that causes root/stalk rot. So instead of waiting for it, I decided to use a few drops preventatively.

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Your solution might be a little strong. I use HP to strike my seeds as well as the original watering in the peat plug (Bacterial disinfection). I use the 3% solution at a ratio of 1:9 1 part HP and 9 parts H2O. 25ml HP to 225ml H2O Hope this helps

Rockwool needs to drain. Set the cubes so they have channels for draining under the middle of them, or place the blocks at the top of net-pots full of clay pebbles.


Did you see foaming on the stem when you used the water/h202? If so, it most likely damaged the plant and created a similar condition to what you're wanting to avoid. Mixing your home-diluted 3.5% with a gallon of water would have been sufficient. 3.5% is very damaging to plant tissue.

Mr. Greengenes said:

Tough one. Throwing ideas out here, what about air circulation? Looking at the cubes, I see the liner pulled up a quarter inch or so above the rock wool creating a little 'pond' of still air around the base of the plant. Made me think about avocados. Avocado trees are SO sensitive to lack of 'air drainage' around their base that they are traditionally planted on hillsides. Maybe by providing more air circulation around the bases of your plants to increase O2? Could work as well or better than the peroxide.

Click to expand...

Dang~! You got good eyes

I didn’t see any foaming at all on any of the plants I treated. Made me think that solution is not strong enough, so no foam at all.
I have 5 fans blowing from the top all over the room, so I have that coverage in place.
I was concidering flashing with plain water

Grodan holds a lot of water. Most folks cannot get a callus to form and the one or two roots that come out are what the plant survives with. Biggest problem is over watering and weak Moms. Moms need to be super vigorous and full of calcium and hopefully cytokinin and auxins, both from seaweed sources.

The stems in that photo show the plant is begging for water. Obviously you have her under a hood.

Sacrifice the worst one and put a sharp knife or straight razor to the cut, trying to cut away to the middle of the stem length wise. A callus should have formed on the cut and there should be no discoloration from the bottom of the cut up through the whole stem. If you have it, that is problem number 1.

Tear that paper off the grodan, that will help it dry out quicker. Always add a couple of drops of bleach to the water you put the cuts in prior to treating them with hormone, etc.

Try to just hit the foliage with a mist, do not add water to the cube after presoaking. Water at the bottom of the tray is ok, but not so much that the cubes are sitting in it. Hopefully your trays lend themselves to that. Important that the water has a pH below 7 or so, preferably using phosphoric acid. If your water is above a pH of 7, it will be more and more difficult to get a clone to root well, much less callus.

Foliar on calcium as often as you can. An amino acid calcium form such as Albion, Baicor, etc.. are the best.

Very awesome info. Thank you.
When they came in on Monday they all were nice and vigorous. I can tell they were cut from a good mother plant.
What you saying is I should remove the sleeves off the cubes and mist the foliage.
What is the mist solution should be?
One thing to mention. On my second try, the plants froze and rolled inwards with signs of stem rot. I was able to check roots on lots of them prior to throwing them away. The roots were white but undeveloped. Most of them didn’t even go into the larger cube.
Thank you.