A few months back I received a call from the crew of RTÉ's Room to Improve. They had a problem garden at the back of a home they were working on in Kildare and wondered if I'd have a solution for a site with an extreme slope.
We often have no idea what we can do to tame slopes and make them usable and even beautiful. I jumped at the chance of working with Dermot Bannon and took a look at what the site had to offer. It was one of those situations where I got lucky. I immediately had an idea that I felt may solve the issue.
It involved removing the existing series of central steps which led up the garden and replacing them with a sloping pathway in a zig-zag arrangement.
Once the slope had been reshaped it would allow for a more gentle climb up to the top where the views of the landscape were magnificent. On either side of the corniche-style path we would plant hundreds of flowering perennials, grasses and ferns with a number of columnar magnolias to give some vertical interest and topiary box balls to add some evergreen structure within the planting through the winter months.
It turned out that the idea was right for the space, Dermot liked it and most importantly the clients Nese and David liked it. The nursery supplied wonderful plants and the garden team worked hard to bring the vision to life. Planting on a slope is a challenge. If the bank of soil is stable it's best not to disturb the ground around it too much. I favour digging individual holes and, when necessary, adding compost or organic matter to these planting pockets rather than loosening the whole slope so as to avoid the soil slipping down the garden or being washed down by rainwater.
The advantage of the slope is that it shows off the plants very well. In Kildare, the garden was almost like a vertical wall of planting outside the kitchen window. Our mix of colour included lavender, hemerocallis, nepeta, verbena, geranium and Alchemilla. If densely planted, a well-chosen mix of plants should soon knit together, leaving little room for weeds to spring up.
Open and sunny sites like our Kildare one are easiest to plant and a great effect can be achieved by even using a single species such as a bank of lavender. This would require an annual clip when flowers are spent but the reward would be a glorious swathe of lavender-blue flowers in the summer.
In a more shaded spot, Vinca, hypericum and pachysandra could do a great job of knitting the soil together as they creep along. There are some lovely bloomers, too, such as Vinca minor Bowles or Hypericum Hidcote which will act as a great weed suppressant.
Flower carpet roses are very vigorous and are prolific bloomers and you can choose from pinks, reds and yellows. These have been bred to do the job of carpeting an area and are disease-resistant. They will require an annual trim and feed but that's about it.
If you prefer a naturalistic look, I'd probably plant a mixture of ornamental grasses, which provide a long season of interest and can look very attractive in winter as well. These only need a cutting back in spring though will require division to keep fresh as the years progress. A good mix would be some tall Stipa gigantea, Imperata cylindrica 'Rubra' with its ruby-red tips, Calamgrostris Karl Foerster, Molinia, and Hakonechloa.
A little attention is needed to establish young plants. Careful watering is required to establish a carpet of colour and over the first few seasons some weeding will be necessary.