1st try w/gritty mix Which plants for large gritty mix? Crushed brick?

5 years ago

First, I would like to thank everyone for all the great posts. I would like to pay it forward sharing my results and have couple questions. This is the first time I've tried to plant sedums and I have two projects a sunny slope and a modular green roof.

I want to grow out stock in order fully plant the slope, that is now covered with dead English ivy. (Triclopyr) I also only wanted to commit so much effort into the green roof, in order to not have mass die off. So, I've started trays (shallow container) with different combinations of substrate composition and depths. I topped this gritty mix with some large pine bark to help control the heat soaked up by the granite.

I've jumped all in finding supplies.

Agway pine bark (One bag screened with #3 mesh)
Turface
Gran-I-Grit
#3 Stainless steel mesh (3 holes per inch) close to 3/8
#14 Stainless steel mesh (both off ebay)
Crushed brick (near the middle with the quarter)

My results.

And now I've got a lot of extra large particle pine bark fines. (Agway) I also have a source for similar size particles of crushed brick. I'm considering getting Gran-I-Grit Turkey (5/16"-7/16") and mixing up a large particle gritty mix. Any suggestions on what plants would do well in such a mix? I realize at some point it might get to porous and not retain much water.

This is all somewhat an experiment. So, suggestions are welcomed.

Thanks again for all the help,

Hosta Collector

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Comments (4)

mblan13
5 years ago
last modified: 5 years ago
Not sure anything would grow in that aerated mix. It would hold next to no water.

I generally use the 1/4 to 1/2 in 5-1-1, and 1/2+ to top dress pots, chuck it in the compost or on the mulched beds in the yard.
gardengal48 (PNW Z8/9)
5 years ago
Living roof soil mixes are very highly engineered to be both lightweight, fast draining and yet sufficiently water retentive. You can't just put anything up there and expect it to work well. Simply because of the weight, I would avoid the gritty mix.........
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Here you go Ruby! The pictures I promised you of my gardenias in the gritty mix. Notice the coloring and buds. They love the gritty mix! This one was tiny since the start of using the gritty mix This one was a cutting I started just this summer. This one was also a cutting. I bought it as a 2inch high high plant in a 2 inch pot!lol. It grew a lot over the summer. It is a special one and a rare one. It opens Yellow flowers and is very sweet. I won't take a chance of loosing this one to a peaty mix. Gritty all the way. This is my frost proof one. I am determined not to loose this one too. This one was saved from MG! It almost died when I first heard of the gritty mix and I desperately transplanted it into the gritty mix with the kind help of Al and Josh and look at it now. Here is a group shot of many other plants in the gritty mix. ALL were bare rooted and many have very sensitive roots. They all did fine:-) You plants will do fine if you listen to the friends here. By the way,Josh has made some more very important points. I wish you success. Mike
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tropicofcancer (6b SW-PA)
5 years ago
Can you post a link to the mesh on ebay? I have looked but did not find.

On a slope you may have to think about how to prevent the mix from sliding down. I believe some sort of mesh is used to prevent that. If the slope is gentle and the plants are established then it may not be a problem. Roofs are certainly more complex.

Sedums can grow on very little soil. I have shallow pots with less than an inch of regular gritty mix with sedums and semps. They do pretty well on their own throughout the year.

Here is one:
Both are experimental handmade pots (hypertufa). The little pot on top of the pot has one semp. The soil area is inch wide and 1/2 inch deep. Both were started last season.
Hosta Collector
Original Author
5 years ago
Thanks for the replies.

I'm assuming you're asking about the 3 holes per inch. I did do quite a bit of searching to find this size. I was only finding expensive whole rolls. Try searching for:

US Stock 3# 304 Stainless Steel Filter Coarse Dense Gauze Woven Mesh 13" x 40"

Good price but it did come folded. Not such a big deal with the larger mesh, i.e., it unfolded easily. But, the #14 was slightly deformed when unfolded.

After reading more about green roofs and finding this site
about the gritty mix, I'm leaning toward a mix with more Turface, less pine bark, and substituting
half that granite with pumice to help lower the weight and decrease the
potential of heat soak. I'm hampered by material availability (only buying
small quantities for testing) and I'm trying to keep costs low. These substrate mixes can be highly engineered. From what I've come across a typical mix is 80% inorganic (expanded shale, expanded clay, expanded slate etc...) and 20% organic (pine bark). Hiring a consultant and getting some proprietary mix is not an option. I'm also not planning on doing the whole roof just parts here and there to keep any added load low. This isn't about Leed
certification or urban storm runoff. (goals of larger green roof projects) I
just want less days where my AC turns on. And to say I've got a blue elves on my roof. It might turn out to be only a place to grow out the sedum while I get rid of all the ivy and give the Triclopyr time to breakdown. I have lot of shade and only the roof and this single slope that gets any real amount of sun.

This is all somewhat an experiment. So, suggestions are
welcomed.

Thanks for any help,

Hosta Collector

Seeing some growth a few weeks in and after some sever storms. Time will tell.

This one had many cuttings taken from it. Nice to see it growing back. These Blue Elf sedums have been hard to come by.

1st try w/gritty mix Which plants for large gritty mix? Crushed brick?

Comments (4)

mblan13

gardengal48 (PNW Z8/9)

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1st try w/gritty mix Which plants for large gritty mix? Crushed brick?

Comments (4)

mblan13

gardengal48 (PNW Z8/9)

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tropicofcancer (6b SW-PA)

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