Are you perhaps one of those unfortunate gardeners that struggle with a sloped garden? As with all things in life, we should look at every challenge as an opportunity to be creative. A sloped garden offer many such opportunities.
The most commonly used garden layout for a slope is a rock garden planted up with succulents, but there is so much more you can do. Creating a sloped garden is however not only about the plants you use, but how steep a slope you are dealing with, how good your drainage is, the suitability of your irrigation system and the type of soil you are dealing with.
For a steep slope you might have to use retaining walls or terraces. Some of our favourites to plant in retaining wall blocks include Agapanthus species such as Agapanthus praecox and Agapanthus ‘Alice Double’ and Tulbaghia species such as Tulbaghia cepaceae var. maritima and Tulbaghia violacea.
These two species very interesting in retaining block cavities because their flowers protrude at a 45° angle.
For a more low maintenance retaining wall garden you can plant succulents. We have a large collection of Crassula species that would work well for this purpose as well as species such as more showy succulents such as Bulbine frutescens and Malephora crocea.
A terrace will enable you to plant plants with a lower drought tolerance. Because much more soil and water is available to a plant in such a terraced slope than a non-terraced slope. Terraced gardens look particularly good with a Mediterranean theme. To achieve this you can plant any of our Felicia species as a neat border and put some shaped shrubs and plants with interesting foliage in terracotta pots of different sizes.
For more gradual slopes you have a bit more options. We suggest you use a combination of trees, shrubs and groundcovers. Apart from looking attractive, the different height levels will stager the rainfall, lessening the impact on the ground and therefore lessening erosion.
The topsoil of slopes are easily washed away by rainfall and irrigation. For this reason it is better to choose plants that do not require a lot of nutrients and water. Plants used on such a slope should also have a robust and well-branched root system to stabilise the soil. We suggest Tecoma ‘Rocky Horror’ and Carissa macrocarpa for shrubs and Gazania splendens and Lobelia anceps for groundcovers.
The success of your sloped garden does not only depend on the plants your use, but also how you design and maintain your garden.
Mulching and installing drainage furrows will help prevent the soil from being washed away and install a drip irrigation system to reduce the amount of water runoff. If a drip irrigation system does not suit your budget you should just irrigate very slowly so that topsoil is not disturbed too much.
Creating a border of plants around your garden beds will also protect your topsoil and you could form berms and swales to slow down and manage fast-flowing storm-water. You should also avoid soil compaction by establishing permanent walkways with stepping stones or paving.