The very worst advice we ever saw given about gardening was given in a popular magazine in an article on Rock Gardens. It said that all you wanted for a rockery in a town or suburban garden was a cartload of stones or bricks dumped down in a corner. We really wondered when we read it whether the writer thought that plants could feed on bricks. Soon after reading this nightmare of an article we came across Mrs. Swanwick’s clever book, ‘The Small Town Garden,’ and we will tell you what she says about the proper way to start a rockery. ‘If people who make a rockery would consider that it is to be made of earth, supported with stones or rocks, they would be much nearer the right method than those who think of a rockery as a pile of stones with a little soil dribbled in among them. If we bear these requirements in mind, it becomes clear that the stones or rocks must be set so as to leave no hollows empty of soil between them, nor niches kept dry by overhanging rocks, and the slope of the earth must be such that the rain will not wash it away, and expose the roots of the plants.’

It may be that a flat, sunny border cannot be spared for you, but that if you choose you may annex a grass-grown bank or slope of a hill going up to a stone wall or to shrubs. We will tell you how we once saw a place of this kind made into a charming rock garden with some blocks of limestone and a few days’ labour. The bank in this case led from an upper lawn to a lower one, and had a south aspect. The turf was all removed, the soil was thoroughly broken and mixed with sand, and then slabs of limestone were mixed into it, each one with a slight upward tilt, so as to hold the earth and catch the rain. The great point to remember about rock gardening is that every stone or rock should be wedged into the soil a little slantwise, so that the hidden end slants down and the end you see slants up. You soon find out an elementary truth of this kind for yourself if you try to grow things in a badly-made wall or rockery. We once watched someone struggle with a loosely built granite wall that tilted a little towards him, and which had no soil in its crevices. He tried stuffing in earth, but as the slant was wrong it fell out as it dried. No rain reached the roots of his plants because the top stones sheltered the lower ones, so nothing that needed moisture would live. Perhaps in the course of years he might have coaxed some of the house-leeks to find a lodging there; but as he wanted a wall garden clothed in spring with hanging sheets of flowering plants, the only way was to pull the wall down and build it properly. Then it had earth packed into every crevice, and the stones so arranged that the rain could reach every plant set amongst them. Some plants, it is true, will live on next to nothing, but there are very few that will do without rain and will survive when their roots have reached a hollow place amongst stones.

We think that while you are a child you will probably not have much chance either of making rock gardens or of building walls; but you may have a bit of wall or garden that easily lends itself to rock plants, and would not do well for anything else. In some parts of England you may have a garden that is rock with a sprinkling of soil on it, and the difficulty will be to find or make places for vegetables and deep-rooted shrubs and flowers. In a garden of this kind the children are quite likely to have a patch where the rocks are showing through the soil, and where it is difficult to find pockets of earth deep enough even for Daffodils or Tulips. But there are many beautiful shallow-rooted plants you can grow in such places as these, for they will not be like the silly heap of loose stones or bricks described in the magazine article. For instance, if you put a bit of the Arenaria Balearica in such a rocky corner as this, it will find its way here and there, clothing every stone with a mossy carpet, and in spring putting out thousands of tiny white starry flowers. Then there is a charming Dwarf Veronica (Veronica repens), that seems content with very little soil, increases at a great rate, and has that pretty way of clothing the stones and taking their shapes. Another of our favourite common Alpines is the Campanula CÆspitosa, a small Campanula that sends up its quivering white or blue bells the whole summer through. It is so hardy and rambling, and increases so fast, that the fastidious rock gardener warns you not to let anything precious grow near it.

You will have to find out for yourself which rock plants are so greedy and pushing that you get tired of their company; for this must depend on your soil and climate. In Cornwall the little Arenaria Balearica spreads so quickly that you soon tear it up by the yard, while in the North of England it seems to increase slowly. In a cold district you may be glad of things that would overrun you in a warm one. Near a town people grow whatever will best endure the soot and close air. When you are older you will have to find out which plants want lime and which granite, which peat and which sand; but we will only tell you of plants now that will grow in any ordinary good garden soil mixed with a little leaf-mould and some small stones, and we will only give you the names of plants that can be got at any good nursery garden. If you can do so, get your plants in little pots, and put them into your rockery or your wall on a showery spring day. But take care that every plant has a good deep pocket of fresh soil to feed it.

Plants for a Rock Garden.

Alyssum Saxatile.—This grows into a dwarf shrub in time, and is a mass of small, brilliant, yellow flowers in spring. It is very sweet, and the bees love it. It looks well near Aubrietias, or near Lithospermum Prostratum. Suitable either for a rock garden or for a loose stone wall in which you can have a deep pocket of earth for its roots.

Antirrhinums (Snapdragons).—We think the good dwarf ones are charming on rockeries. We once had some pink ones grown from Sutton’s seed that were as pretty as little Rose-bushes. On walls some of the taller ones often look well, and when they are self-sown they seem to flourish in chinks where there cannot be much food for them. If you have a wall you should sow a little seed, and be careful not to mistake the seedlings for weeds.

Anthericum Liliastrum (St. Bruno’s Lily).—A charming plant, growing from one to two feet high, and flowering in May or June. It likes a sandy loam. If you want to increase it, you can divide it in the autumn.

Arabis.—If you are a London child, you will have seen this with London Pride in every London rock garden. It is the commonest of rock plants, and its white flowers make a pleasant show near Aubrietias and Alyssum in spring.

Arenaria Balearica.—This is the little creeping mossy plant we have told you of already. Put a bit on some soil near any stones you want covered.

Aubrietias.—You must know these if you have ever looked at a garden in spring. They are in various shades of mauve and purple, and make great sheets of colour on walls and rockeries. It is sometimes called Purple Rock-Cress. You can divide them in autumn, or you can grow them from seed sown in May or June.

Campanulas.—There are many varieties of blue and white Harebells that do well on walls and rockeries. Pumila, Pulla, and CÆspitosa are three well-known dwarf ones. Isophylla is a good hanging one, but not quite hardy. Persicifolia is an easily-grown tall one. They are increased by division.

Helianthemums, or Sun Roses.—These must not be confused with the Cistus, or Rock Roses, which are charming, but not so hardy as the Helianthemums. If you grow them from seed sown in May or June, you should in the following year have a number of dwarf shrubs bearing single flowers in a variety of shades, ranging from white and yellow to bright crimson.

Iberis Sempervirens is often called Perennial Candytuft. We have known people buy it by its Latin name, and be much disappointed to find it was the well-known white flower they had seen in all their friends’ gardens. It is not proud, and will grow almost anywhere.

Iris Pumila and Iris Stylosa.—We mention two out of the many beautiful Irises suitable for a rockery. Try to get the variety of Pumila called Coerulea, a lovely sky-blue. Stylosa is the scented Iris that flowers in winter. It likes sun and shelter, and dry, hard ground. It must be manured.

Lithospermum Prostratum.—If we were only allowed one rock plant out of all there are, we would choose this one. It flowers nearly all the year round in some parts of England, and its blue is as vivid as the blue of a Gentian. If you can plant it so that its roots can tuck themselves under a big rock as they grow, so much the better. We have transplanted a big plant of it successfully, but we did it in fear and trembling, as it is said to hate disturbance. You had better not try to divide it. It can only be increased by cuttings, and they are not at all easy to strike.

Phlox Setacea.—This is one of several varieties of dwarf Phloxes that are useful for edgings and rockeries. They must have sun and well-drained soil, or they damp off.

Speedwell: Veronica Repens.—There are many varieties and sizes of Veronica. Some make big garden shrubs. The one we recommend here is a tiny trailing plant, with small pale blue flowers. It increases at a great rate, and is easily divided. Slugs like it, but do not make headway against it in many gardens. It makes a pretty dwarf edging amongst stones, as it creeps amongst them, and partly covers them.

The Sedums, Saxifrages, and House-leeks, or Sempervivums, are all suitable for rockeries. Some kinds of Sedums, or Stonecrops, grow wild in our hedges. You should get Sedum Spectabile, the Japanese Stonecrop, which bears large heads of pink flowers in August. There are many widely differing varieties of Saxifrage, or Rockfoil; for instance, Muscoides, the Mossy Saxifrage, makes a plump, low cushion of green moss on your rockery; Sarmentosa is the well-known weed, Mother of Thousands; Umbrosa is London Pride. Some have large leaves and pink flowers; some send up pyramids of white flowers from tufts of silvery leaves. You must grow one or two at a time, and get to know them by degrees. Sempervivums are those little green rosettes you see spreading in clumps on old roofs and walls. One of the most fascinating is Sempervivum Arachnoideum, the Cobweb House-leek. It covers itself with a curious white down that looks like a spider’s web. They like a dry sandy part of the rock garden, and full exposure to the sun.

Besides these plants, you should put a few bulbs in your rockery. Some of the very small Daffodils, Narcissus Minimus or Bulbocodium look charming coming up through a mossy carpet of Arenaria Balearica, for instance. You could also have some Snowdrops, some Siberian Squills, some autumn Crocuses, some Fritillaries, and some Dog’s Tooth Violets (Erythronium Dens Canis). We much prefer the English names for flowers, but it is often necessary to give both, so that you should recognize it in the catalogues. We heard of someone who sent to the other end of England for a plant advertised as Tussilago Fragrans, or the Winter Heliotrope, and she was much disappointed to receive a bit of the common Coltsfoot, that was an obnoxious weed in her own garden. Someone else sent for Hieracium Aurantiacum, which certainly sounds a first-class name; but she did not want a bit of the orange Hawkweed, as it had established itself more firmly than she wished in her rock garden already, and had to be kept in bounds with a spade.

We have not given you separate lists for a sunny and a shady rock garden, because we shall tell you a little in another chapter about plants that like shade. You must have some Primroses, Polyanthuses, and Auriculas on your rockery, and though they like the sun in spring, the more delicate kinds need some shelter from the hot summer sun. Try to get Primula rosea, the hardy rose-coloured Himalayan Primrose, and Primula Cashmeriana, a Primrose that sends up heads of mauve flowers on a fat stalk. Both need much moisture. Then, the Japanese Primroses are very handsome, and seed themselves when once established; and Sieboldi, with its many varieties, is easily increased, either by seed sown in spring or by division of the roots.

Now we have chosen just a few flowers for your rock garden, and with every word we write others come and look at us reproachfully, saying, ‘Why are we left out?’ We see neat little tufts of Thrift, or Sea-pink, and hanging sheets of white-flowered Cerastium, Anemones of sorts, Alpine Violas, Forget-me-nots, Hepaticas, Gentians, the finer Columbines, and shrubs of various kinds and sizes. But we have only had one aim in writing this chapter, and that was to lead you just one step towards the rock garden you must make for yourself when you are older. Then you must get yourself ‘Wall and Water Gardens,’ by Gertrude Jekyll, and ‘My Rock Garden,’ by Reginald Farrar, two books that will teach you all that books can about this most fascinating side of garden craft. But from the first one we should like to quote a short passage that tells you how a wise gardener supplements what he learns from books by his own qualities of patience and observation.

‘Nothing is a better lesson in the knowledge of plants,’ says Miss Jekyll, ‘than to sit down in front of them, and handle them, and look them over just as carefully as possible; and in no way can such study be more pleasantly or conveniently carried on than by taking a light seat to the rock wall and giving plenty of time to each kind of little plant, examining it closely, and asking oneself and it, Why this? and Why that? especially if the first glance show two tufts, one with a better appearance than the other; not to stir from the place until one has found out why and how it is done, and all about it. Of course a friend who has already gone through it all can help on the lesson more quickly, but I doubt whether it is not best to do it all for oneself.’

That is excellent gardening advice, and you can apply it to whatever you are trying to do, whether it is a rock wall or a patch of Mustard and Cress.

We must end this chapter with a short list of things we hope you will never allow in your rock garden, and as they are all to be seen here and there, you need not say that the advice is unnecessary. Coloured glass balls, for instance! We assure you that, especially in Germany, there are many people who think coloured glass balls beautiful objects in a garden. Others like bits of quartz, and in cottage gardens you may see sea-shells and broken glass. Then, persons who ought to know better will make a grimy erection with clinkers or broken bricks, and a home for Slugs and Woodlice with a rotting tree-stump. You must do none of these things. If you live where you can easily get stone, have a rock garden in some form, even if it is only an edging of stones to your herbaceous border, and grow some of the plants we have told you of amongst them. If you live where your walls are of brick, you may still get some plants established on them. For instance, where weeds have established themselves, you can remove them, stuff in a little good soil, and sow a few seeds of Snapdragon or Wallflower. Old brick walls make beautiful wall-gardens, and when the builder is not looking you can help on the process in a new one with a chisel, a little fine moist soil, and a few roots or seeds.