Miniature rock gardens can be made in stone sinks or troughs. This is a very popular type of rock gardening, and by no means limited to those gardeners who have insufficient space to accommodate the ordinary rock garden. In fact, stone sinks and troughs form an accompaniment to many rock gardens, and are also useful in various other parts of the garden.
They have a big advantage in that plants can be raised so that they are easily attended to and easily seen, and many elderly gardeners take a special interest in them. Sinks and troughs also form a good disguise for such unsightly features in the new garden as manhole lids and open drains; and they are naturally welcomed by gardeners who must confine their horticultural efforts to some small yard, or to a roof.
The soil used for the garden must be of open porous nature, but also rich enough to support plant life. It must be recognized that sink gardens generally need artificialat some seasons, as it is impossible to use sufficient humus in the under soil to hold moisture during drought.
The sink can be filled loosely with soil, and the rocks then set in place, as effectively as possible, and in such a manner that soil can be filled into the pockets. Fine soil of good consistency is then sifted over the garden, and allowed to fill the pockets and silt down among the rocks. This is best left a day or two to settle, and then the garden is planted with all kinds of dwarf plants.
If possible, one or more dwarf conifers should be used, but these should certainly not be set at the pinnacle of the highest “ hill.” Rampant growers, even those of dwarf type, should generally be avoided. If they are inclined to spread through the soil they will very quickly choke the other plants in the rock garden.
Rock garden specialists generally offer special collections of plants suitable for the sink garden. If these are purchased, care should be taken to give to each the kind of site in which it will thrive. The use of top-dressings of fine stone chippings is almost essential for success, while sand should also be kept handy for the same purpose. Many of the finest alpine plants find a happy home in a sink garden; and sinks of not too large a size can if desired be wintered in the alpine or cold, and moved to the open air of the garden for the summer months.