The success of an alpine garden depends on its visual impact; the most attractive ones look as if they’ve been there since time began. Its style should complement the surroundings: a traditional Japanese design might be jarring in a cottage garden, but would fit into a forested setting. Soil, stone and plants should be appropriate to the site.
Prepare the soil
Every rock garden needs high-quality, weed-free soil. A good mix comprises equal parts topsoil, leaf mould or peat moss, and sharp sand or washed gritty material such as gravel or granite, or limestone screenings.
Select the stone
Use local materials where possible and stick to various sizes of one type of stone. Native rock, available at garden centres and quarries, looks as if it belongs and is usually the least expensive option.
Create the structure
Rocks should look permanent and suggest that more are hidden. Sink each one deeply enough into the soil so it’s secure to walk on.
To build a two-by-two-metre rock garden on a gentle slope, strip the lawn and topsoil. Dig down about 45 centimetres in the middle of the area, allowing the sides to slope inward. Line the depression with a 15-centimetre layer of small rocks or broken bricks for drainage. Add stone chips or coarse sand, and then some good-sized rocks to support the exposed ones. Next, add the soil mix. Water the whole area and let it settle for a day or two before placing the stones.
Starting at the bottom of the slope and following the natural contour of the land, position the rocks flat with the most level side up. Make sure the striations—or grain of the rock—face in the same direction. Tip the stones back as you wedge them into the ground so rain runs into the soil instead of down the slope.