Scree beds | Raised Alpine Beds
Although a rock garden can be difficult to get right, and need considerable maintenance, these drawbacks do not put people off. Often built on awkward slopes, and in shady corners, rockeries are usually the worst choice for these locations because it is difficult to make them look natural.
A sunny situation is essential. Most rock plants like sunshine; those which like shade do not like the drippy overhang of trees.
To look natural, a rock garden must have significant rock outcrops. It should look ‘rocky’. Some of the rocks should be almost completely buried to give the impression of deep-seated natural rock. If a rock garden does not look natural, it fails. Ideally, only rock from the locality should be used. Certainly, only one sort of rock should be used; lumps of concrete, never!
In nature, a scree is the sloping heap of shattered rock that is found at the base of inland cliffs and rocky hillsides. In the garden, a scree bed, or gravel bed, is a form of rock garden - an area of flat or gently sloping ground covered with a layer of broken stone or gravel.
The colour and texture of the stone is attractive and it sets off alpine plants beautifully. Stone has the additional advantage of suppressing weeds and reducing maintenance. Gravel is often wrongly applied as the solution to a weed problem under trees and shrubs. Falling leaves quickly provide rooting material for weed seeds that blow in.
Choose an open sunny position. Scree beds should have at least 5 centimetres of stone to provide an effective weed barrier. Sand or fine gravel should generally not be used because dust and organic material that blows in is washed down to form a rooting layer for weeds. If fine gravel is used, it will need to be regularly raked over to keep it smooth.
The soil beneath a scree bed must be free-draining and open because alpine plants like open soil. Coarse sand, grit or gravel should be added to heavy soil.
A few large stones, perhaps grouped, should be placed on the bed for contrast with the broken rock. Settle them down into the layer of stone. Plants should be spaced well apart and used in groups rather than dotted about. Carpeting and clump-forming alpines are ideal. Scree gardens associate well with paved areas.
Raised Alpine Beds
Alpine beds are very free-draining, raised beds constructed specially for alpine plants. Generally, only alpine enthusiasts go to such trouble, but raised beds are an attractive feature in any garden.
The sides are usually walls about fifty centimetres high. Ideally, these would be of stone or brick; concrete blocks are unattractive. Likewise straight lines, gentle curves are nicer. Leave little planting nooks between the stones for alpines that like to peep out. Because they are made of hard material, alpine beds are best associated with a paved area. Close to lawns and mixed borders, they look artificial.
Drainage is all-important; as much as twenty five centimetres of broken rock in the base and the overlying soil should have gravel and grit added. The surface layer of five centimetres of coarse grit encourages healthy growth and shows off the plants well. A sunny location is vital.