The majority of alpines and rock garden plants have evolved to grow in a soil made up of gravel and rock fragments with a small amount of humus-rich detritus to retain moisture. To successfully grow these plants, it is therefore important to reproduce this freely-draining growing medium as closely as possible. Whilst ordinary garden soil may be modified by adding peat substitute and/or grit, moisture-sensitive species will require a faster draining medium, such as the scree mixture, which contains a higher proportion of grit.

Standard Mix

This medium is suitable for most rock garden plants; the grit or sand ensure good drainage, whilst the humus-rich materials provides moisture retention.

• 1 part sterilized garden soil
• 1 part coarse grit or sharp sand
• 1 part peat substitute (or peat)

Acid-Loving Plants

• 4 parts lime-free leaf mould, peat substitute (or peat ) or composted bark
• 1 part coarse sand

Special Mix

Some specialist alpines from high altitudes (e.g. Androsace species) require an extremely free-draining compost. Use the following mixture:

• 2 or 3 parts chippings or gravel
• 1 part loam or leaf mould (or peat substitute or peat)

Scree Mixture

• 1 part sterilized garden soil
• 1 part peat substitute (or peat)
• 3 parts coarse grit or stone chippings (not sand)

This mixture for moisture-sensitive species may be amended to suit your requirements; increase the proportion of stony material to make a freer-draining compost or reduce it in dry areas. Alternatively, those gardens in dry regions may use a more retentive mix:

• 2 parts loam
• 2 parts leaf mould
• 1 part sharp sand
• 4 parts stone chippings