Talkback: How to make a rock garden in a troughJump to latest post
1 to 14 of 14 replies
1 to 14 of 14 replies
Did Carol say sigloam as her trough filler? 'Can't find that name on Google
Unless you can get guranteed sterile loam with no weed seeds or soil pests, you are better using a commercial John Innes No 3 , half and half with 5mm crushed granite grit, unless you want to grow lime loving plants then you could use 5mm limestone grit.
Wondered if this article I wrote was of any use.
We found a number of these old Belfast type sinks around the garden. This is how I turned them into alpine growing areas.
The sink was scrubbed with bleach to remove any dirt and grease before being painted with a neutral shade of exterior paint. Once the sink has been filled with soil it is very heavy so position it in its final spot before going any further.
The plug hole was covered with a piece of zinc foil. This helps to stop worms from getting in and also prevents the filling material from being washed out and blocking the drainage hole.
To keep the foil in place I put some pieces of stone over it to weight it down.
Next I put a layer of 12 mm gravel over the bottom of the sink to about a depth of 5 cms or so.
A layer of smaller grit and sharp sand was added over the top of the gravel. This was 5cm crushed granite
Now the sink was filled with a mixture of John Innes No. 3 and more of the 5mm gravel, in the ratio of 3 to 1 by volume.
For this sink I used a selection of rocks picked up in the garden, but in other sinks I have used slate, or sandstone slabs or even broken paving stones.
The rocks are placed to create crevices and other planting areas and to give a great depth of soil in places.
More soil is added to fill up the crevices and to steady the rocks.
Finally a layer of gravel was put on top. In this case I used 12 mm gravel to match the gravel used on the area where the sink was to be positioned. It could have been covered with 5 mm grit, or if I had intended planting lime loving plants I could have used a crushed limestone.
A selection of alpine plants positioned where I though they looked best
Planted up and the gravel cleaned up. Job
Can you put a photo on, Elizabeth? You can upload a photo using the tree icon second on the right on the toolbar. It doesn't work from phones.
I have a lovely old granite trough at the bottom of the garden too heavy to bring it up top. Everytime I see a thread on these I want to do it. Perhaps Bekkies OH could lift it
Modern thinking is that one should not put a layer of drainage material in the bottom of a trough like I have done in the past. It just adds a layer of wet material for the roots of plants to go into and rot.
HI, i have recently planted a range of troughs with alpines and followed the process that Berghill describes so well above. Just 2 suggestions. I was advised to use JI no.1 as it has less food in it. Alpines do not need it and you may not want them getting leggy. Second if you place some of your rocks very close together you can squeeze the plant into place and emulate their natural environment. If you look at where they grow above the tree line on mountains they seem to thrive in nothing at all!
Anyway go for it. it is surprisingly easy to do.
More thoughts. Position the trough before you fill it. They weigh a ton and it's there for good. Also the main risk is from winter wet conditions. So you may wish to think how to do this. In the wild they are often kept relatively dry by low rainfall levels and a layer of snow.
Me again. I stood my trough on bricks which are just hidden. The trough appears to float, which is a nice ironic garden touch.Improves drainage too.
If you can get to Wisley the alpine area has a number of troughs planted up in different ways. I particularly like the one with vertical slates/roof tiles, with the plants placed between. You might like to line up parallel slate pieces to look like vertical rock strata breaking through the soil.
There are some pictures of my troughs on the Hello Forkers thread, posted by Gardengirl a few weeks ago.