Case Study - An established garden adapting to climate change. Part 2: The planting design process

This second blog follows on from the first blog which set the scene for the reasons behind this garden design project. This blog explains the design process we go through to reach the planting designs proposals. Read the first blog in this series.

Firstly we thought about the overall layout and structure of the garden and what is already there; were there opportunities to tweak the basic structure so that it worked towards the brief?

More lawn and less planting beds? As planting beds are quite high maintenance due to having to manage the plants, weeds, and watering, what about if there were existing areas of planting that could be turned back into lawns? A lawn still needs mowing but is marginally better than dealing with bare soil, weeds, and plants.

Re-Wilding areas... just let the lawn go wild! Lawn grass and the ‘weeds’ that grow in a lawn (clover, daisies, buttercups, dandi-lions etc) are actually wild flowers that if left to grow become rather nice wild meadows. There is an element of unkempt untidyness about them so you have to learn to embrace them and change your thinking about them. Insects and wildlife love the environment and habitat it creates. Unlike a green stripy lawn it doesnt need cutting every couple of weeks, but when you do, you do need a place to compost all the cuttings.

The concept of a ‘Gravel garden’ is not new. Mediterranean countries with their hot climate and sandy, dusty soil are one big gravel garden. The main thing with a gravel garden is that the soil is a mixture of a lot of gravel within the subsoil and the large pieces of gravel within the soil mean that the soil structure has gaps through which water will flow straight through and not stay in the soil for plant roots to acess. Plants in gravel gardens do not need moisture to survive and actually prefer the dry conditions. As this country becomes more hot and less rainy in the summers, gravel gardens will become the solution.

Making a Gravel Garden: Cover sections of the garden with layer of gravel and stone, mix into soil 4 inches deep, mix of larger gravel (20 to 30mm and small (5 to 10mm). The extra drainage will also help to reduce flooding if it does rain alot. There will be less time weeding as the layers of stone and gravel on-top will act as a weed suppressant. Ideal plants in these gravel areas will those that thrive in these drought conditions. Plants to include; Sedum, Acis autumnnalis, Euphorbia, E. ‘Blue Haze’, Armeria, Artemisia 'Powis Castle’, Phlomis, Echinops, Acanthus, Verbena, Achilea, Verbascum, Santolina, grasses (Stipa, pheasant grass), Germander.

Another idea for the layout of the garden was to have a more permanent structure. The plants are predominately perennials and these need a lot of maintenance throughout the year. They disappear in the winter and only come back in spring and summer. Our proposal was to remove a lot of the herbaceous perennials entirely and add more evergreen plants and shrubs that don't get too big or need pruning but create permanence within the beds.

Taking this idea further is to have more formal evergreen planting, with the majority of the planting being topiary mounds and clipped hedges. Maintenance is fairly minimal and pruning would only need doing once or twice a year but would give a lovely presence all through the year and even in winter when the hedges, domes and spheres get covered in frost and snow. Some examples of evergreen shrubs are Yew domes, Hebe rakiensis, Hebe green gem, H. Green Mound, Ilex crenata/box, Pinus mugo (dwarf conifer). Pittosporum ‘Golf Ball’, Nandina domestic ‘Limelight’.

Another themed area idea would be to have a ‘Stumpery'. There is a long border at the bottom of the garden which is under some trees, shady and close to a stream. Adding old logs and tree roots into the soil would settle in and become like a woodland floor. It will do its own thing and be great for wildlife. Planting would include Ferns, Hostas, Hakenochloa (forest grass), Tiarella, Epimedium, Pachysandra, Rogersia, Helebores.

Changing the types of plants and moving away from the cottage garden style:
A style of planting that my parents have never ‘gone for’ is the Architectural style of planting. However, these would be a great addition to the gravel/Mediterranean sections as alot of what we think of as architectural plants are from these hot countries. Plants such as phormiums, yucca, agave, Dianella tasmanica, Mahonia ‘Soft Caress’, Fatsia japonica, and hard-leaved ferns. Again these plants are mostly evergreen, can cope without water and don’t need much maintenance. They just do their own thing. Some of these plants are ‘succulents’ meaning they have thick fleshy leaves that hold onto water in reserve for when they really need it.

Other ideas for minimising the need for maintenance and reducing water usage:

Avoid plants self-seeding. Brown seedheads can look lovely in winter and are a great source of food for birds, but to limit the sprouting of more plants where you don’t want them, our advice was o try and cut off the faded flowers and seedbeds before they get a chance to drop them onto the soil where they will germinate and add to the weeding!

Mulching. Another way of cutting down on the weeding and keep the moisture in is by mulching beds with bark chippings or other sorts of compost.

Change watering habits. For newly planted or establishing plants, our advice is to try and just do spot-watering of those plants that look like they need it…. ones that are visibly wilting! Adding water to plants that don’t need it is a waste. You may get shorter plants as a result but they will be stronger specimens. And a bonus here is that shorter perennials for example will not need staking or holding back. Don’t let plants become reliant on water by constantly watering. Make them seek out the moisture so they become ‘root resilient’. This means that in extreme heat, the top growth might be burnt in dry weather but below ground they are dormant and ready to go when conditions improve.

The image below shows the ideas for mum and dads garden as described above.