As I am confined to a town garden at the moment, every square inch of ground is precious, so in order to get more plants into a confined space I grow a lot of them in troughs.
Alpines are my main interest and troughs are the ideal containers in which to grow them. All my troughs with one exception are homemade, and that one is an old glazed sink covered with hypertufa.
Making the trough
When I first started making troughs I used the cardboard box method and put wire mesh in the middle to strengthen the structure, but I found the operation a little messy. As I intended to make quite a number of troughs, a timber mould was made from marine ply, which is bolted together at the corners and only takes a few minutes to assemble. The inside part is made with polystyrene sheets that are easily removed without damaging the trough.
With this system no reinforcing wire in required, as the sides are almost two inches thick.
The mixture is made using two parts peat, one part sand, and one part cement, the mould is removed the following day while the mixture is still soft, which gives me an opportunity to mould the corners and sides into a realistic looking stone trough. It is then left out in all weather for about six weeks to dry, by which time it is safe enough to plant up.
A point worth remembering - make sure that you place the trough in its final resting place before you fill it. You would be surprised how many people make this simple mistake, and then have difficulty moving it later. The troughs weather nicely without any special treatment and look quite natural after eighteen months.
Filling the trough
After all the hard work this is the interesting bit. A piece of mesh is put over the drainage holes to keep the worms out, and then a layer of broken crockery pots is placed over the mesh. As I have mentioned before, all my potting soil is recycled and the troughs are an ideal way to use this soil. The troughs are filled to about three inches from the top with the recycled soil and finished with new gritty soil mixture.
The mixture is raised in the middle of the trough about six inches, or as much as I can manage to pile on, without it falling over the side. This is to avoid the flat earth appearance that one often sees when troughs have been planted for some time, and the contents have settled.
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