The Journey to Wilding the Garden January 2024
The year begins with more monumental rainstorms, 55mph winds and floods. Although the wider estate is rather more water than land as the Adur claims the ground well beyond its banks, the garden is relatively unscathed. Like the estate, fluctuations in water levels are accepted and welcomed as a natural process, adding to the dynamism of the ecosystem. The sand and crushed-concrete bowl that holds the ephemeral pond in the Rewilded Garden fills again, and the half-submerged winter leaves of Siberian flag iris ‘Shirley Pope’ and ‘Silver Edge’ wave above the waterline, seemingly unperturbed.
The ephemeral pond seen through winter stems of Chinese silver grass (Miscanthus sinensis ‘Ferner Osten’)
The rain keeps us indoors for a time, planning for the year ahead. We’ll be running new workshops for visitors this season, on landscape and planting design, how we manage the garden, and ‘Vegetable Production – a rewilding approach,’ linking the edibles in the Walled Garden with the more intensive food production of the Market Garden.
We’ve also had time to catch up on the latest podcasts of Knepp’s brilliant ecologist, Penny Green. ‘The Ponds’ and ‘The Microclimate’ episodes are particularly relatable to gardens, where the principles of rewilding in the wider landscape can translate into better practices for wildlife and diversity in the garden.
In ‘The Ponds’ episode, we learn about twelve ponds of differing sizes created in the Southern Block at Knepp by the Newt Conservation Partnership to provide habitat for the protected great crested newt and other wetland species. One of the interesting points Rosie Moss, the project leader, makes about any body of water, large or small, concerns vegetation succession. From the moment an indentation first forms in the ground and water pools there, through to an established pond surrounded by mature vegetation, each state of change provides for a wholly different set of species and lifecycle stages. Within a garden, even the smallest water-tight container dug into the ground and allowed to fill with rainwater can increase diversity. In urban areas, ponds not only provide refuge during extreme weather events but can help prevent flooding and cool air temperatures in urban heat islands.
‘The Microclimate’ episode features a ground-breaking study at Knepp that is part of a wider investigation into microclimates created by the complex vegetation structures found in every rewilding project in the UK. Assistant Professor Rebecca Senior and PhD student Cameron Goodhead from Durham University have installed a series of data–loggers at intervals through Knepp’s Southern Block and are using drone footage and LIDAR (laser technology that measures the distance to objects) to create a 3D microclimate map. Climate change predictions are generally based on data harvested from weather stations, which only give a generalised regional picture and are usually positioned in open, flat spaces. Since Rebecca and Cameron’s data-loggers measure air temperature at various heights (up to 1.5m) as well as soil temperature and humidity, topography, vegetation mass, and the presence or lack of foliage, this study is much more detailed and relatable to living organisms. Much of the daily life of an insect, plant or small mammal – they tell us – is conducted close to ground level, and the range of plant heights and density can have an important impact on localised microclimates.
The principles that have been applied to the Rewilded Garden design – plant diversity, complex vegetation structure and topography – imitates the landscape that Rebecca and Cameron are mapping. Increased vegetation complexity leads to increased diversity of microclimates. As the global temperature warms, an insect finding itself in the middle of an open expanse will unlikely be able to adapt to a 1°C increase in temperature, let alone a possible 2.5°C rise, at the speed of change we’re experiencing. The randomness of the vegetation structure in rewilding projects produces variations in temperature, humidity and habitat, helping an insect shift its range and adapt to climate change. Species heading north or migrating have places to rest, and there is scope for more species to move through corridors and survive. We look forward to the results of this fascinating study and, in the meantime, these considerations will be helping to drive our decision-making in plant choices and management in the garden.
At the close of the month, a frost-white, perfect disc of a moon is cradled in the bare arms of an oak as it sets on a clear morning. The Assiniboine, a semi-nomadic First Nations people of the Northern Great Plains of America, called it the Centre Moon, roughly marking the midway point of the winter months. Its position directly opposite the sun allows the moon’s face to be fully illuminated, giving it a startling clarity – a reminder that spring is now not too distant but that plants, as well as ourselves, need this time of rest. While the orchard is dormant it is a perfect time to join forces with the Knepp volunteers to undertake the winter pruning of the apple and pear trees.
Knepp volunteers winter-pruning the apple trees in the orchard
This annual prune helps preserve the health and vitality of the trees, as well as encouraging flowers and fruit (we supply the fruit for bottled juice in the Wilding Shop). The first step is to take out any limbs and branches that fall under the three D’s – dead, diseased or damaged – and then clear the centre so that light and air can circulate freely. The trick is to pace the pruning. Removing any more than a third can stress the tree and stimulate too much vegetative production. For this reason, we leave the cut stems on the ground so we can check the volume being pruned out. This also creates habitat mounds for insects, small mammals and amphibians in the summer months. Each tree is an individual; each responds to pruning, the seasons and its environment differently. Building up a relationship with a tree over a period of years is by far the best way to manage its care. In the orchard of Woolsthorpe Manor in Lincolnshire, once the home of the great 17th century scientist Isaac Newton, Oxford University identified an apple tree over 400 years old. It’s a pleasant thought to think of these trees in our care going on to give habitat, joy and nourishment long after we are gone.
Left; Upright myrtle spurge (Euphorbia rigida) with netted iris (Iris reticulata ‘Harmony’) Right; Petticoat daffodils (Narcissus bulbocodium)
Although the garden is in sleep mode, the bleached browns and greens muted and toned-down, there are some corners that have burst into colourful life seemingly overnight. The bright yellow splash of petticoat daffodils (Narcissus bulbocodium) and the deep royal blue of netted iris (Iris reticulata ‘Harmony’) can’t help but stop us in our tracks to marvel at their resilience. In a moment when the clouds parted and a small patch of forget-me-not blue sky appeared, we felt our spirits lighten. Josh wondered if there was a word for this feeling brought about by natural changes. Having spent some time in Japan, he recalled there was: Kachoufugetsu meaning ‘the beauty of nature’ – or, literally,‘flower, bird, wind, moon.’ Such simple things we take for granted, a landscape without flowers or a sky without birds unimaginable. Yet almost 15,000 native species of plants and animals are now threatened with extinction in the UK. Our precious green spaces are worth all our efforts to preserve.
Moy Fierheller Deputy Head Gardener January 2024
Photos courtesy of Karen Finley, Moy Fierheller
