8 September 2014
Naturalising crevice-loving ferns
The natural theatre at Allt-y-bela was constructed back in the
spring and is a combination of sculpted grass banks and dry stone
walling. The river which snakes through the grounds at the base of
the new amphitheatre was also enclosed with drystone walling to
protect the banks and create a natural stage behind the granary.
The stone work which looked so new just a few months ago is already
beginning to green up with mosses and lichens with a few plants and
ferns taking up residence.
In order to help the process along a little we have bought some ferns to plant in the crevices along the walls. It's very easy to get carried away when buying plants and to opt for larger specimens in order to add to the initial impact of the planting and this can be a good option. Often though it is better to choose smaller specimens and to let them grow into the spaces in your garden. Plants are usually grown in peat or composts based on light organic matter which is usually quite different from the local soil environment they will be exposed to when planted out into open ground. This can mean it actually takes much longer for larger plants to establish in the new environment. In this case we needed small plants in order to physically fit them into the gaps in the stonework. We opted for plants in 9cm pots and took time to check the size of the rootball to make sure they would be suitable.
We chose three different ferns to use in the walls, we wanted to have a certain amount of variety whilst attempting to create the impression that communities of ferns had naturally developed. We chose ferns that would be found in walls and hedgerows in this area. It is always worth noting plants that grow wild in your area and use the information when planning design elements of your garden that are intended to look natural.
We chose the Maidenhair spleenwort (Adiantum trichomanes), Harts Tongue fern (Asplenium scolopendrium) and The common Polypody (Polypody vulgare) which grows on the moss on trees and on walls in cornwall and should hopefully appreciate the damp welsh climate.
To plant them we got down into the stream bed and looked for suitable crevices; we have tried not to plant the ferns too low as the stream level fluctuates with rainfall and we don't want our new plants to be washed away after the first big storm! The planting is fairly straightforward; it's important to pack the rootball firmly into the base of the crevice while trying not to damage the roots. I tended to squash the rootball into the approximate shape before attempting to insert it into the walls. Once the fern is firmly in the wall it is then important that it has some suitable media to get its root into; in an older established wall soil will have filtered down into the cracks between the stones but here because the walls are new we packed a little soil into the cracks around the fern to help the process along, a splash of water then settled the soil into the stones.
The next really important element is to try to get the spacing right between the plants, the human mind seems to be hardwired to create patterns and in order to get the naturally colonised look we are aiming for it was vital to be mindful of this. I'm hoping that over the winter the stones will continue to take on their new green sheen and that the ferns will grow and thrive and in time start to colonise the other unplanted crevices. The whole effect will soften the impact of the stone work while adding another layer of detail to the garden.
Words: Steve Lannin, Gardener at Allt-y-bela
Photographs: Britt Willoughby Dyer