Place a layer of broken crocks in the base of the trough. This will help drainage and ensure that the roots are never sitting in water.
Fill the trough with compost to within 12.5cm (5in) of the rim. As the container will be quite heavy when filled do this close to where the pot will permanently stand.
Mix a few handfuls of horticultural grit into the top of the compost. This will further improve the drainage of the pot and stop the plant roots and base of stems from rotting.

Place your selection of plants in the trough, ensuring that trailing types will hang over the edges. Choose a position off-centre for the conifer for a more natural effect.
Plant the alpines in the compost, starting in one corner and working towards the opposite edge. Make sure that any gaps between each of the plants and the trough edges are firmly filled.
To finish the trough, sprinkle a thin layer of horticultural grit around each plant. This will stop slugs from attacking plants and prevents competitive moss and algae growing.
Remove fallen leaves from the container's surface in autumn. If these are left on and start to rot, the plants underneath can be damaged.
Protect from excessive winter wet by moving the pot into a sheltered site or covering when necessary with glass sheeting.
Feed the trough each spring.
In hot or windy weather, keep the plants well watered to ensure they do not dry out.
Watch out for slug damage and sprinkle slug pellets or extra grit around susceptible plants as necessary.