Greenhouse Gardening – alpines

Using a greenhouse to grow alpines is profoundly different from most other types of greenhouse use, because all you are doing is protecting the alpines from the extremes of the British weather – which means that there is no heating required, simply a barrier to our all too frequent rain, which damages alpine leaves and flowers and can even rot the roots. This is because true alpines (as opposed to the more widely grown ‘rock garden’ plants) are classified as plants which grow between the permanent snow line and the limit of conifer tree growth, essentially around 6000 metres in height – that’s Matterhorn level! This means alpines are designed for survival in extreme conditions.

Naturally-growing alpines are protected for a large proportion of the year by snow which keeps them dry and at a constant, low temperature, but surprisingly, nowhere near as low as the air temperature above the snow. In spring these alpine plants receive copious amounts of moisture as the snow melts and they make rapid growth and flower ostentatiously in the short time available to them.

This means that to grow alpines in a greenhouse it needs to be unheated, with a well-drained soil and a potent amount of sunshine for the spring months. Many enthusiasts use special alpine shelving (often called pans) that have fine mesh bases and slope, to approximate the conditions the plants are designed for.

Most alpines grow in a soil that is not rich in nutrients and require excellent ventilation at both roof and bench level. Shading of an alpine house is necessary in hot months from spring to autumn.

Greenhouse gardening alpine photograph by leigh blackall, used under a creative commons attribution licence