An Indoor Alpine Display Bed.
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After making one side of the Alpine house into a Czech style crevice garden I decided to turn the staging on the other side of the greenhouse into a fairly standard display bed. I could find no suitable edging material that matched the hyper tufa on the other side, so I decided to carry on the theme and make my own ‘bricks’ with which to build the bed.
I used a fairly standard mix, but because I wanted the bricks to be a little stronger I decreased the amount of coir and increased the sand content, so the recipe was 3 parts coir to 2 parts sand to 2 parts cement.
I was also fortunate enough to have some trays that are 40cms by 28cms by 8 cms (internally). Each tray full made 5 bricks 28cms by 8cms by 8cms. I needed 72 bricks to make the outside walls and a further 36 to go inside.
I lined the mould with a piece of plastic to make the mixture easier to remove.
The mixture was carefully pressed into the corners of the mould.
Then the mould was filled and tamped down to make sure that there were no air pockets.
The mould was then placed in the shed and left for to dry. The length of time to leave to dry depends on the weather. I made this during February/March and the mixture took about 2 days to go hard enough for the next stage. In hot weather it would possibly take less time. The mixture needs to have dried enough to be able to hold together, but still be wet enough to mark.
I used a wallpaper scraper pushed into the soft mix to separate the bricks. The mixture was then left to dry further, before being turned out of the mould. It needs to be strong enough to hold together, but not fully hardened off.
Care is needed at this stage or the bricks break. If they do and the pieces are too small to use for building, then I crumbled the soft mix and added it to the next batch. The plastic was then removed and put aside for the next moulding.
The next stage is to carefully separate the bricks from each other. If they do not fall apart easily I used an old hand saw to cut them.
Now they are left again to dry out a little more. They need to be soft enough to work with. I use a wire brush to give the bricks a pleasing texture. Judging when to do this final work is a matter of experience, too soft and they break, too hard and the brushing makes little impression or is extremely hard work.
Finally they are left to dry thoroughly before work can begin on the next stage.
Construction
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The staging in the alpine house was already in place. This was made from paving stones placed on concrete lintels on brick pillars. The gaps between the slabs provide drainage for the bed and there is no need to leave gaps in the walls.
I used a standard mortar mix to lay the bricks. I could have used the hyper tufa mix, but I find mortar easier to build with.
To help with access I removed the glass from the side of the alpine house. The top pane will not be put back in any case.
Bricklaying skills are not really required as there was never any intention of the wall being absolutely level and in any case the bricks are all slightly different sizes. The joints were staggered however as in any wall building.
The front wall I made two bricks high to give a depth of about 16cms of planting material and the back wall three bricks high so that there is a small slope to the front. Once the mortar was set I put about 3cms of sharp sand in side. From past experience I have found that this sand layer acts as a water reservoir.
On top of the sand I then spread about the same depth of 5mm grit. This has two purposes, to stop the compost mixing too readily with the sand and again to act as a reservoir.
Next the internal walls were put in place. I did not use mortar on these except where they joined the end walls. The back wall is slightly lower than the outer wall and the front one lower still. This slope is only for display purposes.
The compost is my standard mix of soil based, composted bark with about a third added grit.
Finally the whole lot was left to settle before a 2cms layer of shingle was added. The shingle is the same material as used on the Crevice garden. I used this on both to give some continuity between the two sides.
And now for the exciting bit, planting!
