How to create a garden rockery

Where to build a rockery
The ideal place to build a rockery is on a slope in part or full sun. If your garden is flat a rockery can add visual relief but you have to be careful to blend it in so it doesn’t resemble - as celebrated rock gardener Reginald Farrer puts it - “a dog’s grave”. Railway sleepers are ideal for adding height and contours to a flat garden.

Rockeries work particularly well alongside ponds or water courses as well as next to walls. Siting a rockery beneath a tree isn’t recommended because your choice of plants will be restricted to shade-lovers only, also there’s a danger that falling leaves will kill off your alpines. If your garden is on the small side why not consider housing your rockery in a contemporary planter made of fibreglass, zinc or steel.

When to build a rockery
Building a rockery is hard, heavy work so high summer isn’t the ideal time to build. Choose an autumnal or wintry day when the ground is dry. If the ground is moist put down matting or boards to walk on.

Choosing rocks
Basalt, York stone, Welsh green stone, slate and Cotswold stone are popular choices but local stone is always recommended for two reasons: availability and transportation costs. Check eBay, Freecycle or nearby quarries for rocks available for collection in your local area. Failing that contact your local builders’ merchants or head online to a specialist aggregate supplier. For a natural rockery effect flat, rough-shaped rocks are ideal whereas the smooth, spherical types you find at the garden centre are better suited to more modern gardens. But before you order your rocks you first need to…

Start planning your rock garden
Take a piece of squared paper and draw – to scale – your projected space with a rough idea of how your rock formations will appear. Small stones will look out of place in a large scale rockery but remember that big rocks are expensive and tricky to move. A rock measuring approx. 45cm x 23cm x 23cm will weigh approx 43kg, ie 25 rocks per tonne. Heavy work indeed!

Ordering your rocks
This may sound obvious but check when ordering your rocks if it’s kerbside delivery or direct to your garden. Moving 3 tonnes of sandstone in a wheelbarrow is a backbreaking afternoon’s work.

Arranging your rocks
When building a rockery always start at the lowest point and work your way up the slope. Begin by laying an irregular shaped base line of the largest rocks leaving gaps in your 'wall' to allow planting space. Thoroughly embed each rock so it’s securely in place – at least half, and preferably two-thirds of the rock should be buried below ground level. Once you’re happy with the positioning of your first layer infill with planting compost, ideally a free draining soil made up of equal parts compost and sharp sand or grit.

Now start on the next level using smaller rocks, remembering to leave plenty of pockets for plants. At each stage stand back and take a good look at your work from different viewpoints.

Choosing your plants
Plants best suited to rockeries are those which grow slow and low and are happy in dry areas, ie alpines. Before you start planting first set out the plants in their pots to check the layout. Recommended plants include: