Stefan Buczacki and Terry Walton answer all your gardening questions

Colin Peters, by email

Stefan says: This is an interesting question that touches on several points of misapprehension about alpine plants. I think most gardeners now realise that alpines don't necessarily come from the Alps but from mountainous areas in many parts of the world, in most of which snow occurs in some but not always every month of the year.

It's often overlooked that in the wild, alpine plants experience widely differing extremes of temperature, both diurnally, between the scorching midday sun and the penetrating wind and frost of the night, and also seasonally, the mountain peaks commonly being baked in the height of summer but buried beneath snow for months on end in winter.

Rainfall is very high but the air is in constant movement and the soil, or what passes for soil in many mountain environments, is invariably free draining. So I wouldn't rely on the plants being protected by a blanket of snow; place protective cloches over them instead.

Which brings me to the matter of snow cover. In their native habitats, the plants may be covered with snow for long periods but in our climate they're not and this is where trouble can arise because our winters tend to manifest as a few days or a week or two of snow which then thaws, meaning the plants are exposed to both sun and cold. The enemy of alpine plants in gardens is not winter cold but often the lack of it, together with the clinging damp that encourages mould and decay. An alpine plant is defined ecologically by its habitat, not by