If one has only the smallest garden, or even no garden at all, it is often possible to grow what are commonly called rock plants either in a small raised bed or an old converted sink trough constructed between two rows of bricks.
Most rock plants speak for themselves—the very name indicates that here is a plant which likes conditions similar to those it would find if growing amongst rock, though this does not necessarily mean enormous boulders or mountainous crags. The ideal situation naturally would occur in areas of the English Lake District, where such gardens are often made out of a sloping hillside with protruding bits of grey rock emerging through the green grass. Here there can be little difficulty in growing rock plants. Suitable conditions do occur in other parts of England as well as in many other countries, especially Italy and the Dordogne region in the South of France.
Excellent examples of fabricated rock gardens (in neither instance were the natural constituents of a rock garden originally there) can be seen at Wisley and at Edinburgh in the Royal Botanic Gardens. They are two of the finest rock gardens in England. These are, of course, extreme cases, but the same principle can be applied on a much smaller scale by those with just an ordinary small garden, or as I have already mentioned, those with no garden at all.
The first condition that rock plants demand is good. Many of them also like a sunny , though this is not quite so essential. Good can be obtained in small gardens where there may be no natural slope to utilise for this purpose, by raising an area of soil above the ordinary level. The soil, if it is raised up in this way, will probably need some support, and it can be provided by two or three layers of bricks built to surround the area. Large pieces of logs will also be adequate and look attractive, but they will have to be of some size to hold back the weight of soil. A certain number of stones or pieces of rock-like substance can, of course, be also included, but they are not really necessary — this particular side of rock gardening is often taken more seriously than something which I should say is far more important, namely, the quality and type of soil used.
Let us suppose that there is no garden at all, but that there is some space where an old sink could stand, lifted off the ground perhaps on four short pillars made from bricks. First of all one must ensure that the water can drain away. For this reason the plug hole must be cleared and a few bits of old flower-broken up and spread over it so that the water will get through to the soil and then down through its outlet. One of the most effective ways of making sure that this drainage system will keep flowing freely is to cover the broken flower-pot pieces with turf laid with the grass downwards. This will then remain an efficient drain for some years to come.
The soil should be replaced once all this part of the operation is done, with a quantity of what might be described as lightening’ material, that is substances which will help the drainage as well as give ,goodness to the plants. A universal mixture would be difficult to define, for all rock plants do not have the same requirements. This is not surprising if one remembers the different conditions, climates, etc. from which they come and in which they grow naturally. What is possible with a rock garden is to provide small areas described as ‘pockets’ and these can have different aspects and indeed, in special cases, different soils.
Without thinking too much in terms of rare alpines there are quantities of smallsuitable for planting which are invaluable for , especially when a table arrangement is required. Some suggestions follow for this type of planting: Moonshine — there are a good many smaller achilleas suitable for the rock garden, but this is an especially good one with clear yellow flowers and soft grey blue . It is long lasting when cut for arrangement and will eventually dry off and can be used in a dried group.
hepatica—one of the loveliest of all spring flowers and most suitable for a small table arrangement, where they can be well seen. They look especially charming in a small plate garden standing in moss, with perhaps primroses and windflowers. Campanula alba — the spires of some of the campanulas make an interesting contrast in shape amongst shorter stemmed flowers. I like to have the white campanula planted near to the achillea or next to a clump of Jerusalem sage ( Phlomis) or a deep blue iris. The same applies when I use them for cut flower . Campanula alba is also attractive on its own with a few chalk buds of garden ragwort.
— these come in a great variety and are most suitable for rock gardens. It is best to see them growing in a nursery garden and to make a selection there. The foliage is most valuable. Summer starwort ( alpinus) — introduces a note of mauve, which I have found useful for a small mixed group of late summer flowers. Gentiana acatilis—gentians are invaluable for cutting and like dianthus it is advisable to study a catalogue or to see them growing before making your selection.
St. John’s wort—grows into a sizeable shrub with masses of golden yellow flowers. Useful for cutting as a flower. In the autumn thebecome bright crimson or dark mahogany.
—it would be impossible to give a list of names of iris for a rock garden. Again it is advisable to see them growing or to study a catalogue, before making a choice. are invaluable for elating, they give that essential shape and height amongst cushion type flowers.
Catmint () — a soft blue-grey, coming in long, curving spikes which look enchanting when arranged with white pinks.
Phlox—the rock phlox give bright touches of colour and go on flowering over a long period of time. Pulmonaria—known also as ‘soldiers and sailors’, these are amongst the prettiest of early spring flowers, coming in mixed colours of pink and blue. The leaves, rather furry and well-marked, are useful forduring the summer months. —are most suitable for a rock garden and come in so many colours and types.
Saxifraga (London pride) — there are so many different types of this enormous family, but London pride is one of the oldest and best loved. Its small pink-and-white clusters of flowers on the thin redadd a charming light touch to arrangements and later on, when fully developed, will grow into longer stems.
Maidenhair plant (adiantifolium) a small edition of the larger border plant with very delicate foliage.
Thymus citriodorus argenteus—almost any of the thyme family are charming as rock plants and useful for cutting.
The periwinkles are incredibly useful, especially the variegated ones, for their curving stems which they produde throughout the year.