The use of rocks as decorative and symbolic features in a garden goes back to ancient Chinese- and Japanese gardens (also called “zen gardens”). Today, these spaces are known as “rock gardens” or “rockeries”, and although they can flaunt some striking beauty, there are a few things to keep in mind...
What plants best suit a rock garden?
The type of plants you add to your rock garden will largely depend on where you want your rock garden to be placed. If it’s on a shady slope under some trees, a serene green haven can be created by planting various fine-leaved and larger leaved ferns, plus a selection of Plectranthus (available in numerous varieties, from low-growing trailing plants to small herbaceous perennials).
Placing a selection of bromeliads in contrasting colours can look striking in-between the crevices of rocks, while some of the smaller azaleas will thrive in these conditions. Peace-in-the-home (also known as “Soleirolia soleirolii” or “mind-your-own-business”) will quickly cover up the soil and trail delicately over the rocks. For nice splashes of colours, go with some fuchsias and impatiens (or "busy Lizzies").
A rock garden in full sun requires plants that complement one another. Fine-textured or small-leaved plants with large flowers are ideal for a rocky landscape. Gazanias, felicia, osteospermum and the beautiful grey-leaved arctotis are great choices and offset stunningly with the rocks.
Don’t forget the immense collection of succulents to pick from, with vygies and their bright flowers being among the most impressive.
Shrubs can also be planted at the base of the slope while low-growing, spreading conifers can ensure some texture.
The most important thing to keep in mind with rock gardens is to introduce appealing colour, texture and form, and to have the end result look as natural as possible.
How do I build a rock garden?
It might be a good idea to get a professional gardener to assist you with your rock garden project.
1. It’s ideal for a rock garden to include some kind of slope or hill for a natural look, yet not crucial. Shady rock gardens can also work, as they could emulate indigenous flora naturally found alongside rivers and streams.
2. Should you choose to incorporate a slope, the rocks should not form the structure of the rockery, but rather the look. Plant the rocks from the bottom up and, without making it too uniform, dig the holes in a semi circle at the base of the hill. The rocks should be buried about halfway.
3. The next rock level must be planted different heights. Allow for gaps in-between for plants. Always try and use the same kind of rock and keep the weathered side facing outwards.
4. The soil you use must be well drained, so add sand where necessary and ensure it’s well composted. The gaps between the rocks need to be at least 30cm deep to allow the roots of the rocks to sink in nice and deep.
5. Regarding your choice of plants, cascading ones should be planted at the bottom of the rockery, allowing them to cascade gently over the rocks and into the garden. Each gap between the rocks will actually become its own little garden, so opt for plants that don’t crowd one another.
6. Plants can be planted throughout the year, except in the cold winter months.
7. After planting everything and ensuring they are firmly in place, top dress the plants with some compost and treat them to decent watering (careful not to wash away any of the soil).
8. Weeds is one of the drawbacks of any rock garden, which is why it’s vital to weed regularly to keep the roots from getting too firmly established. As most rock gardens are on slopes and the rocks also hold the heat from the sun, the rockery needs to be watered often, especially during hot and windy weather.
9. Think of the gaps between the rocks as individual pots, meaning they need to be fed every spring with compost and bone meal.
Why is soil important in a rock garden?
Due to the way they are structured, rock gardens naturally need good drainage. That’s why it’s vital to fill the pockets behind the rocks with a decent soil mixture to ensure the plants have sufficient nutrients.
A good soil mix for the rockery would be one part garden soil, one part coarse sand and one part good compost or well-rotted manure.
Maintaining a rock garden
A rock garden might not require as much maintenance as a regular garden, but it still needs attention. Keep the following in mind:
· Closely inspect the garden at least once a week, ensuring nothing has moved or slipped.
· Take care of weed as soon as you see them sprouting up.
· Don’t water your rock garden continuously as you would a regular garden.
· Cover the delicate flowers in colder months.
· Remove any dead plant as soon as it’s died.
How to make moss grow on rocks
Moss adds a nice finishing touch to a rock garden, and it’s quite easy to encourage some moss growth:
· Pick a shady and humid spot in the garden for the moss.
· You can transfer existing moss to this new location, or use a mix of buttermilk and yogurt with fresh or dried moss and smear it on the rocks where you want new moss to grow.
· Be sure to regularly maintain your rock garden / moss space by keeping weeds out.