Drainage is probably the most important point to remember. Make sure the trough you use has adequate holes in the bottom.
If using a sink then there will be only one hole. Make a sump at the base of the trough by putting a layer of gravel [at least an inch deep, more if you have room] to allow any excess water to sit and gradually seep away without causing damage to the plants roots. It is important to put a layer between the gravel and the compost. I use old towels or tea towels for this purpose but recommend using garden white fleece which is strong and porous enough to create a good barrier. I have troughs that have been planted for over 10 years and since taking them apart the barrier was still working.
With shallow troughs mound up above rim of container to increase depth in substrate.
Accessories within the trough
You can use rocks [as lumps or as slices i.e. Slate or York stone] to create a small rock garden or you can use pieces of wood such as a tree stump. There are no hard and fast rules. I use both depending on the planting I am doing. If its alpines then I use rocks but if it is woodland plants then I use wood.
Planting with Suitable Alpines
The most important thing about choosing your alpines is to make sure that you use compatible varieties, where one plant will not swamp other plants and the growth rates are similar.
Make sure that all the plants you choose like the same soils. It is no good putting alkaline lovers with acid lovers even if they look good together. You will just waste your time and money.
When planting your trough you will need all year round colour. There is no reason why you cannot use dwarf bulbs but make sure that you use varieties where the leaves do not become overwhelming after the bulbs have finished flowering. Cyclamen coum and hederifolium are ideal for troughs and give you spring and autumn colour.
Choose the majority of your plants as evergreen varieties, so there is interest all year round and look for different foliage types to vary the planting. Sempervivums are useful, as they tend to change their colours with the seasons.
Did You Know?
Many Alpines are compact and make perfect mounds and beautiful shapes.