The return to the garden post-Christmas refreshes our perspective: after the ravages wrought by the extremes of harsh freezing temperatures and biblical rainfall the picture of the rewilded pool garden is predominantly a collage of blacks and browns. Suddenly the silver domes of yellow immortelle (Helichrysum orientale) dotted all through Tom Stuart Smith and James Hitchmough’s planting design stand out, lifting and illuminating the scene, spotlighting the undulating terrain of sand and crushed concrete. They contrast with the honey-beige stands of grasses, chestnut clusters of aster seed heads, and upright skeletal greys of the strangely corrugated purple berkheya. The simplicity found in the clear lines of a winter garden can be as pleasing to the eye as the green riots of summer.
We are in need of some positivity as news from the Met office estimates that 2022 was the hottest year on record. The world’s longest series of instrumental records of Central England temperatures began in 1659, so we have reached a 364-year high. Other notable extremes last year included the south of the country receiving only three quarters of its average annual rainfall; three named storms (Dudley, Eunice, and Franklin) all occurring in the same week in February, where a new record was set for highest wind gust speed of 122mph; and the first two weeks of December recording the lowest temperatures since 2010.
The Met Office’s National Climate Information Centre commented that “The warm year is in line with the genuine impacts we expect as a result of human-induced climate change. Although it doesn’t mean every year will be the warmest on record, climate change continues to increase the chances of increasingly warm years over the coming decades.” Inevitably, our gardens and the native species within them that have adapted to live in a cooler climate will be affected. Part of our surveying and monitoring of the rewilded garden, with its plant community mostly heralding from free-draining, stony habitats across the globe, is to see if a more climate-resilient design can still support an expanding, biodiverse mosaic of plants and wildlife.
It is the dormant time for woody plants, so it is also the time for us to spring into action with winter pruning. In the orchard, we prune the heritage variety apple trees for health and fruit yield – we harvest the crop in autumn to make Knepp apple juice. A rare blue sky arrived with a party of garden volunteers. We worked our way through twenty-four trees, cutting out damaged stems and vigorous water shoots, opening out the centres and tipping back last year’s growth. It is always a pleasure to reacquaint ourselves with each tree, the chatter of conversations and birdsong, the satisfaction of working together toward a shared purpose.
On the walls of the castle, roses, honeysuckle, jasmine and ornamental grapevines, ivy, clematis, and wisteria all need their seasonal rejuvenation. We wrestle fourteen metres of wayward stems into formal structure and prune back laterals to encourage heavier flowering from the bobbing platform of the cherry picker. With these plants, which can be valuable nesting sites and food sources for birds, it is also a question of scale, ensuring the gothic castellated house is evenly ‘clothed’ in greenery when viewed from afar. While climbing plants can involve a degree of management, studies have shown they can bring down the temperature of a building by as much as 7°C in hot weather and reduce relative humidity in winter.
In the rewilded pool garden, as well as the kitchen garden, such formality and dominance over plant behaviour is up for discussion. We loop back to taking our cues from the rewilding project. We imagine a selection of Exmoor ponies, longhorn cattle and red deer faced with a nine-metre expanse of Rosa ‘The Garland’ on the southwest wall of the old dahlia bed. Browsing all the young green shoots would undoubtedly be on the menu, snapping of some older, woody stems inevitable, the topmost unreachable limbs left intact. We reasoned that, as herbivore proxies, we should experiment with an approximation of this animal pruning and include some practical elements. In horticultural terms, removing a few older stems from a rose encourages new growth and prolongs its life (a wild, climbing dog rose (Rosa canina) growing on Hildesheim Cathedral in Germany has reached the age of 700). We will cut back the laterals to imitate the browsing, which will also ensure the perennials in the bed beneath it will have space and light to grow. Then the topmost stems can be left alone, and in this way, we are introducing as much structural diversity as possible into one plant, as the herbivores create a dynamic kaleidoscope of habitats in the rewilding project.
The dark winter mornings continued, bringing cold versions of equatorial monsoon rains that seemed to be never-ending. Wind gusts of aggressive ferocity sorely tested our seasonal resilience. By 16 January, another hard frost gripped the garden, plunging the greenhouse cold side down to -1°C and freezing the now metre-deep ephemeral pond into a splintered fairy-tale mirror. A magical crystalline blanket lay over the whole garden and tiny ice stars rimmed every seedhead like miniature crowns. Faded white streaks of folded clouds obscured the sun and time was suspended, the image unchanged for forty-eight hours.
The frozen ephemeral pond and iced seedhead of wild carrot (Daucus carota)
With the ground frozen solid, the choice of garden tasks were limited. The arrival of the Knepp volunteer group turned out to be fortuitous. Down beyond the orchard, we have built up two brash dead hedges over the last three years. We wanted to limit burning wood unnecessarily, as well as provide a mixed habitat of dead, green, and dry wood to service the needs of a range of insects and wildlife. Two winters ago, we had a family of foxes there, the cubs hiding in the hedge.
Originally inspired by landscape designer Nigel Dunnett who specialises in wild and natural urban gardens, we shaped ours into a horseshoe and a winding snake, hemmed in by upright stakes about a metre apart. We soon realised, however, that in our setting here at Knepp, we were inadvertently providing a food source for the free roaming herbivores, who treated the hedges a little like a snack bar where messy eating seemed all the rage. We are careful about adding any material that is toxic, such as yew or ragwort, so much of what has been added is palatable, or at the very least arouses curiosity. The result was a tousled shambles, the stakes used as scratching posts, the shapes obscured and the surrounding soil a pulverised mush. We had spent a fantastic day before Christmas coppicing hazel on the estate with Knepp’s ranger Tom Burns, and now the combination of adequate materials, hard ground and many hands meant we could build some strength into the structures to withstand the herbivores attentions.
After piling the strewn material back into shape, we set about driving in vertical stakes around 50cm apart. Then the weaving began. Gradually, a tightly woven hurdle emerged, hemming in the brash and redefining the horseshoe shape in an aesthetically pleasing form. A feeling of achievement and camaraderie added to the day as the sun rose into a blue sky.
Head Gardener Charlie Harpur’s sketch of the proposed fencing for the brash dead hedge; Knepp volunteers clear the strewn brash; The finished work.
January can seem the longest of months, but spending time in nature and seeing the detail made large by the dormancy of the garden can be a valuable tonic. Moving aside a pile of leaves with a burbling robin at your shoulder watching for worms and landhoppers, seeing the swelling fruit bud on an apple tree stem or a reddish, frilled rose leaf unfurling, can revitalise a cold grey day. And, in the last week, a cause for celebration and hope for the future arrived – a beautiful baby girl for Charlie and his wife Lizzie.
Moy Fierheller Deputy Head Gardener January 2023
Photos courtesy of Karen Finley, Charlie Harpur, Moy Fierheller
What we are reading;
BBC Sounds – Rethink, Rethink Climate, Green economy, money and prosperity
Ivy-clad walls keep homes cool during summer, RHS research shows / RHS Gardening
