Chapter 2. The Alpine House

There are some choice alpines that cannot be cultivated to the best advantage in the open in our uncertain climate. To say that they are choice does not necessarily mean that they are delicate, but that the blooms of many are apt to be spoilt by inclement weather; it is to these subjects that the Alpine House affords protection while they are in bloom; it will also prolong their season of flowering. Most of the inmates can be brought on during the summer in pans sunk to their rims in ashes or sand in the open, or in sunny frames, until about to flower, when they should be transferred to the house, to be removed again to the open after flowering. After the beginning of October all the plants should be housed in a frostproof frame and must be removed to the cold house as the blooms become visible.

While the plants are in the frame ample air must be provided, but frost must be excluded. The choicest saxifrages, however, are usually kept in the house the whole year through, as their neat and compact foliage is pleasing and interesting even after the flowers are over, and does not get ragged and untidy.

Culture Of Alpines In Pans

The culture of alpines under glass is comparatively no new hobby with the amateur, but one whose popularity is increasing rapidly. The plants, except the bulbs, which should be planted again each autumn, require but little attention and only need repotting every second or third year; this is best carried out in July or the early part of August. Although the house is as a rule unheated artificially, the plants will furnish a mass of interesting and brilliant bloom, while the neat, and in many cases unusual, foliage of such subjects as the Shortias, Achilleas, Sedums and Saxifrages will provide unbounded interest in the off season. Great variety of bloom may be had, since a large number of specimens can be kept in quite a small space.

The alpine house does not necessarily require artificial heating, although a row of hot-water pipes round the sides is an advantage. In such a case care should be taken to keep them away from the plants, as scorching is instant death to alpines. They are only required during the dark, damp, foggy days (especially in cities) of winter.

The alpine house is best of the low span-roof type, so situated that it runs north and south; both sides then get their fair share of the sun.

Campanula Cochlearifolia Nasturtium "Golden Globe"

Ventilation And Shading

If, as suggested, a span-roof type of house is used, it will be found most convenient to have a centre path and stagings, that will raise the plants up near the glass, down both sides; the plants will then be easily accessible.

The stagings should be covered with a half-inch layer of shingle or fine ashes.

Ventilation

Ample provision must be made for ventilation, for the plants require a fresh, cool atmosphere, and plenty of air, but no cold draughts. Upon the proper ventilation much of the success of the alpine house depends. It is very easy to kill, or at least gravely to injure, a house full of plants by injudicious opening or closing of the ventilators. Only in summer when the temperature is too high, should top and side ventilators be opened simultaneously.

Generally only ventilators on the side opposite to that from which the wind is blowing should be opened.

The amount of air admitted depends of course, on the nature of the plants; young, growing plants and seedlings require a warm and moist atmosphere, while plants in bloom require the air to be drier. Where there is ample top ventilation there is less need of side ventilation as well; indeed, many experts now discontinue the use of side ventilators altogether; this I consider a mistake. It is important that the temperature of the house should be watched, especially in the morning when the sun will often come out suddenly with surprising power, and unless the ventilation is regulated in time, the heat will become intense. In order to avoid the risk of scorching, the ventilators should be opened early in mild weather, beginning with a small aperture, which is gradually increased as the sun becomes more powerful, reversing the process towards evening as the temperature falls.

Violent changes of temperature are as harmful to plants as to people. Frost and Fog must also be carefully excluded.

I find it an advantage where possible to build a small rock garden on each outer wall of the Alpine House to within one foot of the stage and so help to keep the gradual temperature during one's absence inside the house.

Shading

Some means of shading the house should be devised. No definite dates or hours when shading should be commenced can be given, as everything depends upon the weather prevailing. The alpine house, however, usually needs shading from about the end of April, and should be shaded each day as soon as the direct rays of the sun fall on the house. The blinds may be removed as soon as the fiercest rays are passed. Moderate sun will not hurt the great majority of alpines; it is only the fiercest rays of midsummer that must be warded off. Protection from only the direct rays of the sun should be provided. Where constant attention can be given, an arrangement of roller blinds is, of course, the best, as the amount of light can be better regulated, and the blinds may be left up on dull and sunless days. Where, however, as is often the case, the alpine house must of necessity be left to look after itself for a good part of the day, the simplest, and the most satisfactory, method is to paint the glass over with a mixture of whiting and milk, or purchase one of the numerous green shading mixtures now on the market, care being taken to cover all small air bubbles, etc., so common in the cheaper glass, for these act as lenses and intensify the sun's rays.

The solutions are easily washed off when cloudy weather sets in. Shading is rarely necessary after the end of September.

Compost And Potting

Most alpines thrive in a gritty, well-drained soil. Two-thirds fibrous loam and leaf-mould with one-third coarse, gritty sand makes an excellent compost for most of them.

Many of the finer saxifrages like a little splintered limestone or some old lime rubble, similar to that used in carnation culture, in their soil. Individual tastes must be studied.

Pot-up in pans from six to nine inches in diameter and about five inches deep; and since ample drainage is required, place two and a half to three inches of broken crocks in the bottom of the pans for plants like the Androsaces and the Saxifrages.

For subjects of a more vigorous nature and for bulbs, one inch of crocks will suffice.

Watering

Alpines require ample water during their growing period and while in bloom; but care must be taken to see that the drainage is adequate, for a stale, stagnant soil is the alpine's greatest enemy. Plants will need most water in the spring and summer. Water at least once a day, sometimes twice, at this season.

Dormant plants and those freshly potted are best kept rather dry until growth begins.

A watering once a week, or even less frequently, will suffice for most plants in winter time; but the soil must be prevented from becoming dust-dry.

In the summer the watering should be done when the sun's heat is at its lowest, early in the morning or in the early evening, but in spring, late autumn, and in winter it is essential to water in the morning, so that excessive moisture may have drained off before the evening, otherwise there is great liability to "damping-off." The more tender alpines should be stood in a shallow tray with one to two inches of water in the bottom, so that the water may percolate up by way of the drainage without damping the foliage; this is especially necessary in the case of those plants with dense, downy, or waxy foliage which nestles close to the soil. Plants should never be allowed to become so dry as to droop, for this may cause irreparable damage; but if this has occurred, the whole plant, pan, and all, should be stood in water deep enough to cover the pan. When thoroughly soaked, it should not at once be replaced on the staging, but should be put in the shade for an hour or two to recover.

Many plants, and especially those that have not recently been repotted, will be the better for a watering with mild liquid manure every ten days while the buds are forming. This must be discontinued as soon as the flowers are out.

Cleanliness In The House

Cleanliness inside the house is most essential. Aphides, thrips, red spiders, mealy bugs, scale insects, and woodlice are the chief pests met with here. The manner of countering them is shown in the chapter on Diseases and Pests, where fumigation and sterilization are described. Keeping every corner of the house and the stem and foliage of every plant as clean and free from rubbish as possible will do a great deal to keep down insect and fungus attacks.

Propagation

The plants are mostly increased by division of the roots, which is best done almost immediately flowering is over. The newly-potted plants should be kept in a close frame, shaded from the sun, until the roots are established; usually in about fourteen days.

For treatment of bulbs, see Bulbs in Pots, See also chapter on Propagation.

The Alpine House
*A11 Dwarf Alpines should be grown in shallow pans, not pots.

NOTE. The various types of Saxifraga (Rockfoil) require a book to themselves as they are innumerable and all are ideal subjects for cultivation in the Alpine House.

For bulbs suitable for culture in the Alpine House. See also list of Dwarf Shrubs.

NOTE. The plants shown in the list for the Miniature Rock Garden may also be grown in the Alpine House, but to save space have not been repeated in the above list.

The Alpine House The Miniature Rock Garden

Of recent years this type of indoor-gardening has become a source of great interest to amateurs. It consists of a rock garden in miniature constructed in some suitable receptacle, usually a large earthenware pan. This, however, is not essential; in fact, the little plants are much more effective when displayed in an old pig trough or stone sink. These may be picked up at any country sale for a few shillings; those found in many parts of Westmorland and Yorkshire are particularly beautiful, being hewn out of solid limestone or sandstone. Sinks are especially adaptable, as they already have the outlet; the troughs would have to be bored to provide for the necessary drainage of the soil.

Construction. The stone used in the construction of the small rockery usually consists of rugged pieces of limestone or sandstone, although these are not essential. Cork-bark or old clinker burrs dipped in cement wash of the right colour make most realistic weather-worn stones, and very often give a much more picturesque effect. A most important point to be considered is suitable drainage, and this may be secured by putting two inches or more of broken crocks, cinders, etc., over the bottom of the trough: the thickness of the layer depending largely upon the depth of the container. Cover this coarse drainage with a sprinkling of finer material to prevent the soil from sifting down and clogging the drainage. Over this spread a layer of half-rotted leaves; these will tend to retain a certain amount of moisture, and will also assist in keeping the soil from mixing with the drainage. Fill the remainder of the trough with soil to within half an inch of the rim so that, when watering, the water will not wash the soil over the side.

The compost should be of a gritty nature, something on the following lines: one-third part loam, one-sixth part leaf-mould, one-third part quarter-inch chips and sand, and one-sixth part peat.

This may be varied to suit the particular requirements of the plants grown. Two to three inches of soil will provide ample rooting medium for the plants.

On this bed of soil the garden should be built, excavating for valleys and pools and building up with stones to form miniature hills. It will be found much easier to insert the plants as the work goes on, than to plant when the garden has been built.

Great care must be taken to pack the soil firmly round the roots of the plants.

On pages 51 and 52 is a list of plants suitable to the Miniature Rock Garden. A few dwarf shrubs should also be included, the selection made depending, naturally, upon the size of the garden to be planted.

Plants For The Miniature Rock Garden

NOTE. For Fuller Cultural Details, see Chapter 12, Alphabetical List of Plants for the Rock Garden, etc.

NOTE. For bulbs, see Bulb List; for shrubs, see Shrub List.

[R. A. Malby Adonis Apennina

Achillea Ageratifolia

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