Rock Gardens

Rockeries can form the most delightful features of any garden and, contrary to general belief, can give colour throughout the year. They begin flowering with dwarf bulbs in January and finish in December with more dwarf bulbs and late autumn-flowering carpeting plants. Naturally, there are highlight periods of bloom, but a rockery’s overall contribution to the colour and variety of a garden cannot be over-emphasized, especially when used in combination with water. But it must also be stressed that to keep them looking attractive, the amount of maintenance required by rock gardens is high compared to other forms of gardening.

PREPARATION

As with a vegetable garden, preparation of the site is of paramount importance. The entire area should be dug and any perennial weeds dealt with. Remove persistent offenders by chemical means if necessary, for once the rocks are in place it is extremely difficult to eradicate weeds. If you are keen to make a rock garden but have no natural slope on which you can begin, then you will have to set to and dig, throwing up the soil to make mounds and hollows of suitable size and shapes. Rock is expensive and so must be used sparingly and sensibly. The great illusion is to make it look as if there is more rock than in fact exists. However, rocks should be set into the earth solidly to ensure stability, often to at least half their depth.

CONSTRUCTION

In my experience the most economical form of rock construction is the outcrop method, where the stone looks like little outcrops emerging from a gentle slope. This occurs in nature, as in the limestone hills of northern England for example. It helps to remember that all rock starts off as a solid lump, which is then split horizontally and vertically by natural weathering. So when you construct a rock garden avoid placing the rocks as if they are bonded, like a brick wall. Continue any strata lines right down through the design in one direction, either horizontally or vertically, to make the whole look more natural.

Building a rock garden can be strenuous work and to prevent injuring yourself, various items of equipment are quite useful: a sack truck for transporting rock; wooden planks to prevent wheels sticking into soft soil; and a crowbar to manoeuvre the rock into position at the last point of resting. Do remember that once in place a rock garden is a permanent feature. Get the setting of the stones correct the first time. They should be tilted backwards slightly to allow rainwater to trickle down to the roots of plants. Rocks should be rammed into place and firmed with a wooden rammer or the reverse end of a cold hammer or trowel. Check carefully that they are stable and properly balanced before stepping on them.

CHOOSING THE STONE

Choice of stone is very important; I share the dislike of many in seeing the wrong stone in the wrong area. For instance, in a limestone area I consider that limestone is the best material to use. But if your local natural stone is sandstone, then limestone can look out of place. Local stone will be cheaper to use as transport distance will be less. It is transport that increases the cost of rock. There is one local stone that is welcome in almost any rock garden. This is the soft porous rock called tufa. It has no strata lines and so is easy to use. There are also man-made ‘rock’ materials.

SOIL

If you wish you can construct little beds of rocks into which can be placed different soil mixtures. Then, for example, you can grow peat-loving plants in a slightly alkaline soil area by adjusting the soil accordingly.

If your soil is heavy, then a tremendous amount of drainage material in the form of chippings should be incorporated with the soil. The essential thing about the alpine plants mainly grown in rock gardens is that they all require good drainage.

When the rock garden is complete and planting undertaken, the whole area can be top dressed with chippings. These have a three-fold effect: they conserve moisture; look neat, tidy and natural; and they protect the collars of the plants from rot at soil level. Ideally, die chippings should be of the same material as the stone, but this again is an expensive undertaking. In most instances washed river gravel is just as acceptable.

When planting, remember one golden rule: in nature you never see an upright tree at the top of a mountain, so always place upright-growing plants at the base of a rockery. Conversely, plant only low-growing conifers or alpine species on the top of the rocks.

If it is not possible to create a rockery in your garden, you can still grow alpines very effectively in troughs and raised beds.

Excessive drainage, and you will need to decide whether or not to impede this drainage to retain the water. Likewise, if a stream flows through your property, good use can be made of it. But first check the source of the water supply; if it flows through an area that is polluted, it will not support much plant and fish life. Before deciding to include a water feature, you should consider whether it will be safe if children are to be regular users of the garden.

12. May 2013 by admin
Categories: Featured, Garden Management, Top Tips | Comments Off on Rock Gardens

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