We have a new member from Seoul, Korea. He would like to know if anyone knows how to make a suitable rock wool substrate for sedum cultivation, to use in roof gardens.
Lee, this is a good place to post your questions for us. Hopefully we will be able to help you.

Jacki, I know you have some experience with this. Twit you are an awesome researcher also. Is there any one here that has knowledge on the topic?
Here are some sites I have found that talk about using rockwool.

Rockwool: This is a material manufactured from rock minerals, often used in insulation, or as a growing medium in greenhouse crops. The roots of the roof vegetation can penetrate it, and the friction between the rock wool and the bitumen roof makes it lay still in place. Rock wool can hold a lot of water, and release it to the plants over a longer period, but also drains off any excess water.
In very light weight solutions, rockwool is used as a substitute for the substrate, plants grow directly in it, and gravel is sprincled on top to stop the mats from blowing off. This solution doesn`t hold any long term nutrients for the plants, and so has to be fertilized.

http://www.greenroofs.com/Gree...
http://www.greenroof.se/?pid=3...

I've never used this for green roofs, so I'll be interested in knowing more about it.

I think green roofs are the future!

Oh me too - as well as other green building techniques - the picture above is Glory Be, the root cellar, build right into the hillside so it's earth sheltered and the front walls are cordwood. What a fun project!

I would love to have a house built into the side of a hill or partially into a hill. I think it would be super!

I agree - it would be so cozy!

A friend of mine built a berm house. No green roof though. A small wood stove set on low kept the entire house warm and cozy during the coldest winter weather (Eastern WA). It was a two bedroom, 2 bath house with a large office. Big open concept living room/dining room and kitchen. When you drove up to it it looked quite small. I think it was 1300 sq ft.

Oh that sounds wonderful! When you've spent the last ten years in a horrible 30 year old trailer, a nice, small, handcrafted, cozy cottage is so appealing. Soon!

Here are pictures of planted sedum on rock wool substrate .
1) picture of inserted cuttage of sedum into rock wool board .
2) picture of sprinkled cuttage of sedum on the wetted rock wool and rooted
within 15 days .
rock wool property
density :90kg/m3 , porosity :97% , easy cutting and holing , wettable

Very interesting looking leeyoungjoo- are these some that you planted? Did you find the information you needed to make it?

So, the flats that the rock wool is in, what are they like? They look shallow - what is the bottom like? Drain holes?

We have a factory close by that makes rock wool insulation for building houses, I'll see how that works in the springtime.

Thank you for posting the pictures leeyoungjoo. It is so interesting to see them growing in the rock wool. I am curious also as BlueFox is as to depth of the trays. I also like what I can see of the tables you have them sitting on. We would love to see more photos. I understand you also grow sempervivum in the rock wool?
How long have you been growing in this manner? Do they eventually need other organic matter added?

I'll definitely try this - the Roxul rock wool is thicker than the pics, so may work differently. I like the idea of planting Sempervivum in it, cut the rock wool to fit into flats, then just the friction would hold them in place with no need for the netting. Hmm, I think we're onto something! Can you imagine panels for a mosaic hung vertically?

Leeyoungjoo, I think you have turned some of us in a new direction on creatively using our sempervivum and sedum. : )

@blue fox yes, we can see the 7cm thick rock wool board is in the styro form box has drain holes and 2cm thick rock wool board in the plastic tray has drain holes.
We can slice the rock wool as we want to the thickness 2~15cm around.
@valleylynn I do not know the name of sedum yet. I am a beginner in sedum , only 20days before I try to propagate the sedum on the rock wool substrate, but in tomato or bell pepper horticulture I am 15 years expert .
@blue fox yes we can dig hole by ball pen or cutting by knife and insert the root of sempervivum
And can fasten it by the cutting wool In the rock wool and let it stand vertically ,
In vertical stand rock wool , water content on upper side is higher than bottom .
Please order to me any test , any examination in the rock wool , I will do it.

WOW...this is so interesting! So, can we use the same rock wool material that is used for insulation? I think this would hold plants in place better than soil. Maybe I'll do a collage on the side of my building....
Sounds like fun to me, I wish things grew faster or maybe I just need to buy more...

Isn't more better Linda?

I am wondering the same thing about the insulation. Can you answer that Leeyoungjoo? Is the rock wool the same as house insulation material?

The material itself is the same, but it comes in different configurations and thicknesses. I've seen it made into little plugs wrapped in plastic, for sticking Poinsettia cuttings, which once they're rooted get potted into larger pots. I'm planning a wall mosaic too - can't wait until spring!

I've been researching it on the internet. Sure wish they had photo of the rock wool fluff. Not sure what it is like.
I found that you can buy it in blocks and cut it to size.

I also read if you left the plastic on the blocks it promots algae & mold growth. They recommend taking the plastic off.

After reading about it, I'm not sure I want to use it. Many greenhouses have lots of waste from using it. We have enough things to bury that will not decompose.