The Alpine House for Growing Alpines
The Alpine House
This romantic sounding name is given to the completely cold greenhouse (no artificial heat whatsoever) utilized for the culture of hardy low-growing rock plants including shrubs. It gives them protection to a certain degree from the extremes of weather and certainly from the ravaging effects of cold winds, enabling them to flower earlier and with more precision than if they were out of doors. It is a form of activity that can occupy an enthusiastic gardener over the winter and early spring months, and of course is a necessity for the rock-gardening enthusiast keen on exhibiting.
Many gardeners automatically think of all rock plants as being extremely hardy and able to withstand very low temperatures because they are indigenous to high alpine valleys on inaccessible rock shelves where, obviously, the average air temperatures are low. They forget, however, that for a major portion of their life many of these alpine plants are protected by a thick insulating blanket of snow which provides an even-temperatured congenial environment. Grown artificially below the snow-line in the variable autumn and winter conditions of a temperate climate, rock plants often quickly deteriorate.
Broadly speaking, any type of greenhouse will suffice, provided it is situated in a sunny position and — perhaps more important — provided it is well ventilated with both side and ridge vents to keep temperatures down.
Benches covered with inert gravel or pebbles arc desirable and tiering is useful to give effect and better space utilization. Plants are potted up in the summer, using clay pots for preference, and an appropriate compost — broadly speaking one of John Innes No 1 standard with either lime or no lime according to species. Goodis essential, using broken crocks or pebbles in the base of the pot. Pots are plunged to the rim in a shady sheltered position and kept moist, and the plants arc lifted into the greenhouse in mid-autumn, where they must be kept cool and watered according to temperature, but generally sparingly. Small-flowered spring bulbs are potted in late summer or early autumn and plunged in ashes in a cool shady frame for five or six weeks before being brought into the greenhouse.
It is essential to give continuous air day and night on the top ventilators at least, except during very cold frosty weather, and water very sparingly according to growth. It helps to keep plants moist and at the same time looking attractive if the tops of the pots are dressed with a layer of inert chips of suitable colour, preferably grey, white or red.
Shrubs may be grown in much the same way, using larger pots, and there is obviously a vast range of species to choose from, size being the limiting factor. Full lists of species can be obtained from specialist nurseries. The following arc some of the more popular species grown:
Anemones A, aspennina, blanda, fulgens and stellata
MiniatureNarcissus bulbocodium (hoop petticoat), cyclamineus (cyclamen-flowered), minimus (with tiny ) and triandrus (angel’s tears)
Conifers, many dwarf varieties