The term "alpine" is usually employed interchangeably for rock plant and frequently the plants are the same, but rock plants grow at any elevation among rocks (or in sand), while alpines are on mountain tops above the timber line and up to perpetual ice. They were first labelled on the Alps of Europe, but now from any mountain peak on any continent. They are minute plants, usually tufted, and cannot compete with the vigor of plants of larger growth.

True alpines would thus be far more difficult to grow in garden soils and at sea levels, and for the average rock garden where most of us live, it may be avoiding disappointment to omit them. Yet after Arabis, Iberis, and Phlox have overrun the rock garden, we feel like tempting fate and attempting alpines. You need to exercise all kinds of crafts in the construction of an alpine rock garden. The soil areas must be narrow and perfectly drained below and on the surface.

Gravel and rock chips may be inserted freely in the soil mixture, and you must provide a rooting depth of at least three feet. The soil in the crevices must be of very poorest quality and reach far back into the bank. This is the first and greatest requirement. Surface drainage is the next real worry, so be cautious with any garden water features. If water stands for any hours about the crowns of alpines, off they go, to return no more. The pockets must be raised above the adjacent soil or given a steep slope.

There is no possibility that the surface drainage will be too nearly perfect, and usually the dead plants will proclaim that you did not even get near to the desired perfection. The next provision must be to compensate for the lowering of the altitude of their home. Few of us have gardens at an altitude of two or three miles, where the air is cool and moist. On flat plains, in the dust and heat of cities, do we expect these mountain plants to thrive?

As well expect a polar bear to feel at home on a city sidewalk in August. Much can be done to alleviate their suffering. Near the sea or bodies of water, or wherever the winds come moisture-laden, the air moisture will help somewhat, but in hot, dry summers the alpine garden should be wet with the sprinkler at evening if there are not heavy night dews. The morning shade should be retained as long as possible, to keep the benefit of night dew for the greatest number of hours.

Alpines must have full skylight and free air circulation, not in shade of trees or buildings; yet rarely should they feel the full force of midday sun. Thus, the greatest possible use must be made of the low angle of slope to the north, with plenty of upstanding rocks to cut the rays of the sun. A bank facing directly to the north is ideal as an alpine possibility, but best of all is a deep cut like the sides of a sunken drive running some- what east-west, with a cool breeze drawing through from woodland or lake.

Such natural ravines are frequently found and they may be constructed at some expense. If alpines can be kept out of baking sun and in a cool air, most of them may be coaxed to live. This is especially true of all the smaller Saxifrages. One more detail, the most essential, is surface drainage close about the crown. An alpine is impatient with wetness among the foliage and should have a pack of stone chips holding the crown from the soil below.

It seems foolish to feed the plants every year with chips of rock the size of grains of corn, but this does the trick, and winterkilling and frost-heaving are unknown when the chip blanket is present. As for winter protection, the north slope and chip blanket will take care of the mild winters, and in the cold winters with plenty of snow, the alpines begin to be interested in their new home.