For many of today’s gardeners, the inspiration to build planting areas amid stone and gravel comes from concerns over climate change and the increasingly common threat of drought; for others it is simply about creating the perfect environment to set off particular groups of plants. Whatever your reason – an attempt to recapture the feel of a Mediterranean garden or an alpine hillside in your own back yard, or a desire to be more eco-friendly – rock gardening can offer a surprising range of possibilities.
Choosing the Site
Although you can build a rock garden on any free-draining site, they do best in a sunny aspect, so a south or south-west facing slope is ideal. Whichever type of feature you are planning, the most successful are those which resemble the sorts of rocky outcrops found in nature – partly because they look right and partly because they seem to meet the needs of the plants better.
Building a Rockery
Once you have chosen your site and removed any turf, if there are perennial weeds they will need to be dug out or killed, as it will be almost impossible to control them once your rock garden is established. The next step is to build the base with 6 inches (15cm) of coarse rubble and then cover it with overturned turf or a perforated plastic sheet, which allows drainage, but stops soil from washing into the rubble layer. The rocks themselves need to be properly bedded down in a thick layer of topsoil to stop them from moving and then the gaps between them filled up with good topsoil or a suitable compost.
There are two main tricks to a successful rockery. Firstly, use large rocks; using ones that are too small ruins the effect and can simply make it look like that bit of your garden is just stony, rather than part of an attractive and deliberately landscaped feature. Secondly, create a variety of different planting pockets when you lay out your rocks. It helps to make the whole structure look more natural and although most rockery plants enjoy the sun, one or two do not – so they need to be provided with more sheltered spots to thrive.
Once you have planted your new rockery, top-dress it with a layer of grit or fine gravel to complete the overall look.
Forming a Scree
Scree forms naturally on the slopes of mountains, as the rock is gradually weathered. The small stones which break off from the “parent” rock fall down and gradually accumulate forming a loose layer of pebbles, providing a home – albeit a rather precarious one – for a variety of plants. Many of these are very specialised – including plants such as Anchusa cespitosa and Vitaliana primuliflora – but their unique charm and beauty makes them well worth the effort needed to recreate a bit of their natural habitat to grow them for yourself.
A scree really needs a slope – forming a deep bed of rock fragments of varying sizes with a very free-draining compost mixed in – and often really works best with one or two larger rocks added in to give it a feeling of height. Where space permits, integrating scree-beds with a traditional rockery can be used to make a very dramatic and natural looking feature.
With the all-too-familiar threat of summer hose-pipe bans, gravel gardens are becoming increasingly popular and imaginatively finished with drought resistant plants, they offer an interesting alternative to traditional lawns and borders. The ground beneath the gravel garden needs to be open and well drained – which may mean some work to improve the soil structure before planting – and it is important to make sure you have dealt with any weeds. However, the pay-back is that once established, gravel features are one of the least labour-intensive ways to garden.
Planting options include a wide range of Mediterranean plants for warm, sunny plots, while a number of native coastal plants such as thrift (Armeria) or sea lavender (Limonium) will do well in cooler or more exposed sites. Adding a few planted containers or a self-contained water feature can often be a very effective way to introduce a little extra contrast and interest.
A well thought-out rock garden complements any plot and can fit in particularly well in the compact grounds of many modern houses. The small, resilient plants which thrive in these stony environments have an appeal all of their own and can reward a modest amount of care with a surprisingly large splash of colour when they flower. Provided you plan carefully and build your rock garden well to begin with, they are hard to beat for low-maintenance impact.