The notes that follow are meant as a rough guide. As to design and type of troughs this is up to the individual and everything can be varied to suit your own taste.
There are many different types of troughs about. Many people own old granite or slate troughs that they have inherited from their families which look superb, but oh the back!
Old sinks are another option, which can either be left as they are or can be covered in a hyper-tufa mix to make them look like the old traditional troughs. If you have an old sink then be careful with the drainage. There is only one hole so you must make a sump. This is covered under drainage.
Then there are the modern lightweight troughs that I use for showing. These are so real looking that you easily mistake them for the real thing. These are ideal for moving around even when they are filled with compost. However these are no longer made and so if you see one for sale then snap it up as they are very much in demand.
If you want to make your own trough then the ingredients are as follows:
- by volume 1 part cement
- 2 parts coarse sand
- 1-2 parts moss peat (put through a 6mm Sieve]
Don’t increase the peat content, as this will weaken the structure. Remember to make drainage holes in the bottom and don’t get too ambitious and make it too big.
I have in the past suggested that people use John Innes No 1 mix as this has the lowest feed level, which is suitable for alpines. I have however found that this compost ends up like a brick so I now suggest mixing multi-purpose compost with it 50/50 to give a freer mix. Add a little grit to help drainage.
If making up a sempervivum trough, then use either cactus compost or a poorer grade compost and mix with plenty of grit. Sempervivums do not require much in the way of feed and the harder they are grown the better the colours.
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. They are strong and porous enough to create a good barrier. I have troughs that have been planted for over 5 years and taking them apart the barrier is still working.
With shallow troughs then use old crocks over the drainage holes to allow water to escape.
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 is 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 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.
Using a top dressing helps keep the moisture in the compost in summer and helps suppress weeds to some degree as well. There are many types you can use, all freely available from garden centres or DIY srores. Use gravel or grit that compliments the rocks that you have used and don’t use too large a grade otherwise it can look silly for the size of trough.
Note: Rinse the gravel through thoroughly as there is always a lot of sediment in the bag and this will leave a residue on the plants. After top dressing water well.
The Siting of your Trough
This is very important. If you intend to place your trough in a hot sunny south facing position then you must remember that your trough will heat up very quickly on hot days and the plants must be able to tolerate this.
Plants such as sempervivums, sedums and delospermas but using just these types would make it very boring.
I prefer troughs to be placed where they get the morning sun and the afternoon shade but I realise this isn’t always possible, but does allow you to enjoy a healthy planting mix throughout the year.
Remember also that if you put your trough on a pathway or next to the lawn then it may get knocked frequently.
Troughs look fine not only on their own but also as a group of 3 or more. This can give you a very pleasing effect.
When siting your trough it is a good idea to place them onto feet. This stops any problems with drainage as this allows any water to drain away quickly regardless of how wet they get. It also stops ants making your trough their home.
Looking after your Trough
Water your trough well when you first plant up your trough. Do this for a few days to allow things to settle and starting growing. Once established then you should only need to water about once a week or when necessary. You cannot abandon your trough after this. Like all pots left on patios/paths that you may have in your garden they dry out when it is warm so you must keep an eye on the trough and water when needed. When watering, do so either early in the morning or later in the evening when it is cooler, to stop evaporation. This will also allow the plants to take up more water and will stop scorch.
You should not need to feed your trough for the first 18 months to 2 years. After this you can use a liquid fertiliser, but dilute it down to a weaker feed than suggested on the bottle. Alpines do not need a lot of feed so it is better to do a weak feed more frequently.
Many Alpines are compact and make perfect mounds and beautiful shapes.