For best growing conditions you should use a freely draining compost to plant your alpines. Add a layer of broken crocks in the bottom of clay pots or a layer of grit in the bottom of plastic pots to ensure that water will not stagnate in the bottom of the pot and suffocate the roots. Most alpines will grow well in a mixture of equal parts of loam-based potting compost and grit.
Alpines that are native in high, alpine habitats of scree and rock-face crevices and any cushion-forming plants need a less fertile and more freely draining mix in order to maintain their neat, natural habit. If you grow these types of alpines in a rich compost they will become quickly soft and lush. This way they will be more prone to pests attacks and diseases. For these plants you should use a mixture of up to three parts grit to one part loam-based compost.
Alpines that are native from woodlands or those that grow in humus-rich pockets in rocky habitats will prefer a well-drained compost that is rich in organic matter. For these alpine you should use a mixture of one part loam-based compost, one part grit and two parts leaf mould, peat substitute or peat.
Before planting any plant make sure you check on the individual needs of each plant before selecting the appropriate compost. Make sure that for lime-hating plants you chose ingredients that are all lime-free. To avoid any planting problems, specially on alpines that need a less rich compost, introduce them to their new medium while they are young. This way they will adapt easier to the new medium, especially if they have been potted on from a more fertile medium.
After planting up the pots you should top-dress them with a layer of grit or stone chippings. This will prevent the growth of mosses and liverworts, will keep the neck of the plants well drained and not at last, will enhance the plants appearance. Use a top-dressing that is appropriate to the pH requirements of each plant.
You may also be in position to repot some of your alpines when they have outgrown their pots. Transfer them carefully into a slightly larger pot, disturbing their roots as little as possible. Repot herbaceous and shrubby plants in spring and summer, when they are growing strongly, and bulbous plants when they are dormant. Plant them in their new pot at the same level as they were planted in their old pot. Firm in fresh compost and then add a new layer of top-dressing. Water well after potting by standing the pot at least 2.5-5 cm of water until the top of the compost becomes moist, then remove the pot to avoid the risk of root rot.