Rock wool

Kikaida · December 18, 2015

Has anyone used this for germination then transfer to soil? Thinking about buying small 1"x1" sheets. Heard mention that they absorb water like crazy and that as your plant grows, the stem will typically be wet which could be a bad thing.

Worth1 · December 18, 2015

Ive heard of it before but never done it.
As far as the wet stem is concerned the best thing to do is always use a 1 or 2 parts hydrogen peroxide to 8 or nine parts water in your spray bottle.
This will kill the micro organisms that cause damping off of the stems.
Just eye balling the mixture is fine.
What I am using now is the hydrogen peroxide solution with 1/8 teaspoon of MG in a pint spray bottle.

Worth

Kikaida · December 18, 2015

Cool, thanks Worth!

Cole_Robbie · December 18, 2015

Don't breathe the dust. It is also a mild skin irritant.

The trick is to maintain the right moisture level in the rockwool. Soaked is not best. Something like about half the water the cube can hold is optimal.

RayR · December 18, 2015

You have to soak rock wool in a PH adjusted solution before you use it since it is very alkaline as it comes from the factory. It's a rather expensive way to start seeds but it's popular with some folks using hydroponics as a seed starting and cloning media.

kurt · December 19, 2015

Here in South Florida I tried it in cloning,works great,but tended to show green algae,mold after a while.As usual at seasons end all my spent mediums go into yard and a mini mulch pile.The rock wool does not biodegrade as per literature.In Europe it is becoming a environmental hazard.The stuff keeps popping up in yard over the years. Here is a article with some insight.

http://www.epicgardening.com/rockwool-harmful/

Ricky Shaw · December 19, 2015

With plus 90% germination rates easily attainable using the same media as for growing, why spend a penny more on anything else?

kurt · December 19, 2015

With a circulating fertigation system(i.e.ebb/flow/pump)as I have seen in some greenhouse operations and private hydro grow systems dirt,soils,peats,coirs will hinder the piping,filtering and hygiene of those operations.From what I gather the intent of rockwool,grow stones,lava ships etc. are primarily used in the hydro grow systems.

Ricky Shaw · December 19, 2015

Yes, it would certainly hinder in a hydro grow. Maybe it was another thread, I'd thought for some reason the OP was using fabric pots.

Kikaida · December 19, 2015

Just got some Black Gold seedling mix...Maybe another time.
-
Thanks for the replies!

HiPoha · December 21, 2015

I have used rock wool cubes for starting tomato seeds in my hydroponic tray and had good success. Seeds sprouted and grew fairly fast and healthy. Transplant to soil was good. But I have a problem with white flies out in the garden which causes my tomato plants to fail. Been out of tomatoes for over a year now. Maybe I'll try planting again next month.

December 18, 2015	#1
Kikaida Tomatovillian™ Join Date: Apr 2015 Location: Valencia, CA Posts: 258	Rock wool Has anyone used this for germination then transfer to soil? Thinking about buying small 1"x1" sheets. Heard mention that they absorb water like crazy and that as your plant grows, the stem will typically be wet which could be a bad thing. __________________ Fun FIRST, safety second...

December 18, 2015	#3
Kikaida Tomatovillian™ Join Date: Apr 2015 Location: Valencia, CA Posts: 258	Cool, thanks Worth! __________________ Fun FIRST, safety second...

December 19, 2015	#6
kurt Tomatovillian™ Join Date: Oct 2011 Location: Homestead,Everglades City Fl. Posts: 2,501	Here in South Florida I tried it in cloning,works great,but tended to show green algae,mold after a while.As usual at seasons end all my spent mediums go into yard and a mini mulch pile.The rock wool does not biodegrade as per literature.In Europe it is becoming a environmental hazard.The stuff keeps popping up in yard over the years. Here is a article with some insight. http://www.epicgardening.com/rockwool-harmful/ __________________ KURT

December 19, 2015	#8
kurt Tomatovillian™ Join Date: Oct 2011 Location: Homestead,Everglades City Fl. Posts: 2,501	With a circulating fertigation system(i.e.ebb/flow/pump)as I have seen in some greenhouse operations and private hydro grow systems dirt,soils,peats,coirs will hinder the piping,filtering and hygiene of those operations.From what I gather the intent of rockwool,grow stones,lava ships etc. are primarily used in the hydro grow systems. __________________ KURT Last edited by kurt; December 19, 2015 at 10:47 AM.

December 19, 2015	#10
Kikaida Tomatovillian™ Join Date: Apr 2015 Location: Valencia, CA Posts: 258	Just got some Black Gold seedling mix...Maybe another time. - Thanks for the replies! __________________ Fun FIRST, safety second...

December 18, 2015	#2
Worth1 Tomatovillian™ Join Date: Feb 2006 Location: Den of Drunken Fools Posts: 38,539	Ive heard of it before but never done it. As far as the wet stem is concerned the best thing to do is always use a 1 or 2 parts hydrogen peroxide to 8 or nine parts water in your spray bottle. This will kill the micro organisms that cause damping off of the stems. Just eye balling the mixture is fine. What I am using now is the hydrogen peroxide solution with 1/8 teaspoon of MG in a pint spray bottle. Worth

December 18, 2015	#4
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	Don't breathe the dust. It is also a mild skin irritant. The trick is to maintain the right moisture level in the rockwool. Soaked is not best. Something like about half the water the cube can hold is optimal.

December 18, 2015	#5
RayR Tomatovillian™ Join Date: Jun 2010 Location: Cheektowaga, NY Posts: 2,466	You have to soak rock wool in a PH adjusted solution before you use it since it is very alkaline as it comes from the factory. It's a rather expensive way to start seeds but it's popular with some folks using hydroponics as a seed starting and cloning media.

December 19, 2015	#7
Ricky Shaw Tomatovillian™ Join Date: Aug 2015 Location: Zone 6a Denver North Metro Posts: 1,910	With plus 90% germination rates easily attainable using the same media as for growing, why spend a penny more on anything else?

December 21, 2015	#11
HiPoha Tomatovillian™ Join Date: Jun 2012 Location: Hawaii Posts: 130	I have used rock wool cubes for starting tomato seeds in my hydroponic tray and had good success. Seeds sprouted and grew fairly fast and healthy. Transplant to soil was good. But I have a problem with white flies out in the garden which causes my tomato plants to fail. Been out of tomatoes for over a year now. Maybe I'll try planting again next month.