Talkback: How to make a rock garden in a trough

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