Ornamental Horticulture

4. ROCK GARDEN

ROCK GARDEN

A rock garden is the arrangement of rocks with plants growing in the crevices. Its bold ruggedness is a pleasant contrast to the softness of the flowers. The stones help the plants in retaining their moisture and keeping their roots cool. In plains, on the sunny side some of the cacti and succulents, Lantana, Setcreasea, Verbena etc., can be grown successfully. Ferns and some indoor plants also look natural on the rockery slopes in shade.

Site selection
A rock garden should be situated in an open part of the garden. It is often advised that a shaded corner of the garden should be devoted for making the rock garden. The rock garden should get all the sun possible or at least for half the day, preferably in the forenoon.
Construction of the rockery
The placement and selection of rocks is an important factor. Rocks should be of local origin, porous, and have a weathered look. Granite is unsuitable, whereas a weathered limestone is ideal. Lime stones from the quarry can be used as they weather quickly. Stones of uniform size having a diameter around 60 cm should be selected and a few stones should be as large as can be handled without much difficulty.

Rock plants do not grow exclusively on rocks, and, hence, a good soil is needed for every rock garden. In the hills, there is no problem in selecting the soil as the natural soil is the best soil there. The soils obtained from where the paths are laid will make the mounds and ranges. In the plains, a soil full of coarse sand, plenty of leaf-mould and well-rotten farm yard manure is quite suitable for most of the plants. In addition to leaf-mould, fine compost suitable for rock garden can be prepared from the cutting of the turf by the usual method of composting. Only the few centimeters (15-45 cm) of the top layers of the rockery will have this compost. The sub-soil should be well drained and have the property to absorb sufficient moisture. If it is not naturally so, this can be created by adding sand or gravel.

Management of the rockery
In places having a severe winter, delicate plants will need protection. When plants are small a glass sheet resting on the rocks may be placed over the plants. For larger plants four strong galvanized wires may be inserted in the ground and the glass placed over this. If the weather is very cold the sides should also be covered with glass or polythene sheets.

The rock garden should be weeded periodically and all dying or dead leaves and branches are removed. Rock plants are replanted every 4 to 5 years or they may be top dressed every year with a mixture of compost, garden soil, fine sand, and leaf-mould in equal proportions. Periodically the rock plants may be fed with liquid.