The Knepp Estate in West Sussex is now world famous for its rewilding experiment, with two farmers giving over their 3,500 acre farm to natural forces, with the resulting explosion in rare wildlife making its home in the scrub and long grasses of the once grazed fields.
Isabella Tree and Charlie Burrell have now turned their gaze to the house’s walled garden, which was preserved mainly as a croquet lawn. Learning from their observations from over 20 years of the rewilding project, they were keen to experiment, and see if one could ‘rewild’ a large domestic garden.
She enlisted the help of garden designers Tom Stuart-Smith and James Hitchmough. The goal of the project was to see how garden biodiversity could be maximised. The hope was that the garden would be led by natural processes, and also be lower input (maintenance and water), allowing plants to ‘move about’ and self-seed or die.
Charlie Harpur, Head Gardener, explains the process. “We used what resources we had available to create a spectrum of different soil conditions in the garden. At one end we had our existing sticky and rich Sussex-clay, but at the other we created harsher, more free draining soil mixes using tonnes of crushed concrete, brick and sand leftover from an estate building project. Much like we have observed the grazing animals in the rewilding project doing, we sculpted the landscape to make it more diverse, creating lumps and bumps”.
The philosophy behind the winding paths and creation of a more 3-D landscape was to create as many different habitats and niches – areas that don’t drain so well, areas that are baked in sun, some in shade, damp corners all with differing PH levels “Varying the range of habitats as much as we can creates maximises opportunities for biodiversity, and we can study which plants thrive in which locations and the wildlife they attract”
He acknowledges that selective weeding is still needed – a process he calls ‘grazing’ – which mimics the herbivores in the wider landscape. “Much like grazing, weeding is a selective process. Just like herbivorous animals know what they want to eat, we know what we want to keep or remove. Regular disturbance like this suppresses the dominant species and opens up spaces for other plant species to colonise.”
“Gardens,” Charlie explains as he leads us though a narrow overhanging path, “can be at the top the pile when it comes to biodiversity, because of the range of opportunity that they can offer”.
“We have tried to think outside of the box to take the principles of large-scale rewilding and apply them to a smaller, domestic space. Unleashing grazing animals into our gardens is not always practical! But in the unique realm of the garden, the gardener is the keystone species. Thinking this way helps us to see the garden in a different way. We are able to tailor the plant selection to the different habitats that we had created. For example, in the wet Sussex clay we went for Siberian Iris, Sanguisorba and Veronicastrum as they have evolved to cope with having wet feet for part of the year”.
“We even allow docks to grow as their deep tap roots renovate the soil and provide crucial food sources for larval insect species. It’s not hard to snip their seedheads off to stop them taking over”.
When they first took a survey of plants in the walled garden before they started on the new layout, they found 150 species. Two years later they have 1000 species which have made the garden their home. They are monitoring insect and bird species too to indicate changes in biodiversity overall.
“There are some principles that one needs to consider” he explains.
‘Messy Ecosystems, Orderly Frames’ – This is a title of a paper written by American academic Joan Nassauer and it refers to our human need for a degree of order, or care, to appreciate a landscape. “We do this in the garden by keeping the paths tidy and clear as a strong contrast to the perceived messiness of the beds. It shows considered curation of the garden”.
Not obsessing over soil richness – if the soil is too rich plants will put on a lot of growth and dominate others, so less plants, flowers, seeds and diversity.
Keeping track of biodiversity – this can be the most exciting aspect seeing new life come into the garden and make the ‘messiness’ valuable and desirable.
Allow change and flux – this principle allows plants to do their own thing, so its learning to trust nature and be surprised and curious of the changes that happen each year, rather than trying to keep a garden in a fixed state- good lesson for life!
Charlie’s advice for local gardeners – work with what you’ve got. Use whatever materials you have available, experiment by creating different habitats in your garden. Try piles of rubble, logs, don’t over-tidy, leave standing vegetation as habitat through the winter, and see the opportunities for wildlife in all plants (even the weeds!)
The Knepp Walled Garden is open for Garden Tours and Workshops, or self-guided visits, but booking is necessary. You’ll find the details on the Knepp website. They start in April this year and run until October.
Apart from being busy in the vegetable patch:
You can give Shrubs like Cornus And Salix a hard prune back- look on the RHS website to see how ruthless you can be!
If the water starts warming up you can start feeding the fish.
If you haven’t finished pruning your roses now is the last time to do them before they come into leaf.
Lastly, look up summer flowering bulbs and tuber plants such as Dahlias. They can be planted now, or in the next few weeks
Where to visit in March
High Beeches Gardens, Sussex
This is a 25 Acre garden which is a botanical treasure trove that includes historic magnolias.
Laid out by the Loder family, but inspired by Victorian horticulturist William Robinson’s wild garden style, is it really worth going to when all the plants are coming into leaf.
It is open every day except Wednesday, 1pm-5pm. 01444 400589.
And don’t forget the Tulip fair at Arundle Castle 1st April