SUCCESSFUL ALPINE GARDENING AND THE FORMULA FOR DON'S SECRET SOIL MIX
BY DON HERZOG, MINIATURE PLANT KINGDOM
IF VIRTUALLY SCALE size miniature plants would bring your layout to life, you should read this article. The generic name for those beautiful and realistic looking little plants with tiny leaves and flowers is "alpines" because many grow in high mountains. They tend to do well in dry, rocky places with practically no soil but excellent drainage.
Our interest is in the "scree" types. They grow as tiny buns, cushions, and creepers with minute leaves and flowers. They are very slow growing and cultivating them creates no changes.
A "scree" is the area at the end of a glacier where the rock has broken down into chips and sand. Scree plants are usually under snow from around October to May and receive no water until the snow melts. Thunderstorms irrigate them through the late summer and fall. So most alpines do best in an open, sunny, well-drained position where they receive adequate moisture during the growing season.
NOW THE SECRET FORMULA
To provide the best growing conditions in places without excellent drainage (such as clay soil or loam), you should import a soil such as decomposed granite. The best place to put the soil is in a raised bed at least six inches deep. Then, into the bed, and over the decomposed granite, you should place DON'S SECRET SOIL MIX. I have developed it for use on my own layout over a non-draining base and it has given superb results.
2 1/2 parts 1/4 minus fir bark
2 1/2 parts perlite
2 1/2 parts peatmoss
2 1/2 parts lava rock
1 1/2 parts river sand
Add fertilizer according to local needs.
If you are unable to find a particular ingredient, substitute whatever comes closest; the idea is to provide excellent drainage.
FINAL THOUGHTS
Some alpines do tolerate soil but most do not. It seems ironic but the best soil in the world for growing giant vegetables may be deadly for alpines. If necessary, alpines will grow in nothing but fir bark, rock, or sand.
In areas where the soil is very heavy you also may have to provide a drain to remove excess water. Do that by digging a trench in the ground, setting in a drain pipe at a slight angle, and covering it with crushed stone or gravel two or three inches beneath the decomposed granite.
During the remainder of this series I will be referring to Alan Bloom's book, Alpines For Your Garden. It is the best book I have read about alpines for outdoor railroads. It has excellent color photos, describes more than 150 plant families, and is easy to read.
Next time I'll tell how to choose the best plants for outdoor railroads from each alpine family, where to place them, and how care for them.
