The Journey to Wilding the Garden February 2024
The Roman king Numa Pompilius added February to the Roman calendar around 450 BCE. Its original position was at the end of their calendar year and it was the month that concerned itself with honouring the dead, closure and atonement. The sombre, subdued tones of the garden certainly reflect this month of slumber. The standing dead stems and chestnut, russet and black leaves are gradually losing their form, succumbing to weeks of wet, the temperature regularly in double figures. It seems the weather has taken the tears of atonement to heart.
But this is also the time to get down on hands and knees and look carefully: the buds all along the stems of the Persian white lilac (Syringa x persica ‘Alba’) are tiny green spheres balanced like birds on a wire, latent life ready to burst into leaf and flower; the apricot and peach flowers are held in plump green sheathes; the spurges cyathia unfurling and colouring more every day. Their acid yellows and burnt reds are a perfect background to the carpet of deep-blue dwarf netted iris (Iris reticulata ‘Harmony’). In the Kitchen Garden, the 300 snowdrop bulbs we planted one wet November day last year have emerged like white cotton balls sprinkled through the rhubarb beds, befitting their common name ‘fair maids of February’. Some of those wildflowers that have found their way into the garden under their own steam are also in full flower. The European native daisies (Bellis perennis) with their jolly white-maned yellow faces standing out from the gravel paths and the buttery flowers of lesser celandine (Ficara verria) are both valuable nectar sources for queen bumble bees and other early emerging insects.
The common daisy and lesser celandine, both valuable food for early emerging insects.
There’s food for us, too, amongst these native flowers. Celandine leaves are remarkably high in vitamin C, and young leaves in early spring can be eaten raw in salads (older leaves become toxic as they age) or cooked like spinach. The common name of pilewort points to its medical use.
The unopened flower buds of celandine and dandelions, just forming now, can be pickled in vinegar and used as substitutes for capers. The nutritional value of dandelions (Taraxacum officinale) is extraordinarily high, and all parts of the plant can be eaten raw or cooked, preserved, roasted, used in salads, stews, soups, as teas, coffee and to flavour beer and soft drinks. It is truly puzzling how such a valuable garden plant is so vilified by the traditional horticultural community and seen as such an eyesore. According to the National Trust, dandelion flowers are visited by 93 species of insects including 15 types of moth. For pollinators, it’s more a case of a sight for sore eyes.
The eagerly awaited invertebrate survey report from pan-species surveyor Graeme Lyons arrived this month with some exciting results. This garden is an experiment, a question; can a garden increase biodiversity and still function as a space shared with people? In order to measure whether our redesign of the Walled Garden will actually increase biodiversity, we commissioned a baseline survey from Graeme in 2020. Knepp’s ecologist Penny Green has also been monitoring the garden for birds, bees, butterflies and moths every month. Graeme’s invertebrate survey will be carried out every three years. Once a month, from April to September 2023, Graeme collected samples to identify, sweeping and beating with a net, suction sampling, grubbing, searching flowers and bare ground and turning logs for two hours every visit – quite a work-out on a hot day. It’s important, here, to point out that Graeme is measuring species richness rather than abundance – ie identifying different species rather than estimating numbers present for each species. Species abundance is often overlooked when quantifying biodiversity, but it is hugely significant because high numbers of even common species provide food for others. However, counting numbers of individual species is costly, complex and time consuming. Generally, it’s accepted that high species richness suggests good habitat which will equate to high abundance – at least for many species.
We were obviously hoping for some increase in species from our pre-garden redesign baseline and we were not disappointed. The garden’s insect tally had leapt from 333 species in 2020 to 434 in 2023. A 33.3% uplift in insect species in just three years was staggering. The number of nationally scarce or rare species reached 35, 14 more than were recorded in 2020. The largest upsurge was in beetles – a total of 108 species, of which 11 have conservation status, an increase in numbers from the baseline which recorded 86 species, six with conservation status. We were pleased to see that three of them are saproxylic (depending on dead or decaying wood). Over the last two years we have been attempting to curb our learned behaviour as gardeners to clear away all dead branches and stems from the garden, while at the same time keeping the amount of decaying material within reason. It was a real boost to hear our approach has paid off.
One of the leaf-eating species identified in Graeme’s findings is the delightful tortoise beetle that feeds on goosefoot or fat hen (Chenopodium album) and orache, a spinach alternative (Atriplex hortensis). Both are non-planted, self-seeding incomers we allow a certain freedom in the Kitchen Garden. Their leaves and seeds are edible, the former used widely in Indian and Nepalese curries and for some time as greens in this country. Carbonised remains of ‘fat hen’ have been found in Iron age and Viking storage pits.
The tortoise beetle Cassida nobilis is one of the notable species now present in the garden that was not recorded in 2020
Tillus elongatus, with its eye-catching scarlet band, is one of the nationally scarce saproxylic beetles recorded in the garden that is also new to Knepp. The rarest species of the survey, which Graeme has only ever encountered once before is another saproxylic beetle, Xyletinus longitarsus.
Above: Xyletinus longitarsus, the rarest find of the survey
Below: Another saproxylic beetle, Tillus elongatus.
The number of bees has risen from 21 to 36 species. And an impressive 90 species of spider were recorded (an increase of 17 species), including Argena subnigra, a small, nationally scarce spider with a spotted abdomen which favours warm, dry, broken turf and is an indicator of good invertebrate habitat. The remainder of the 2023 results included 70 true bugs and 44 true flies as well as species from another 13 orders. Some truly impressive findings.
Graeme also identified 22 non-native species in the survey. He attributed the increase to the small percentage of imported plants we have introduced into the garden after the baseline survey, that came from outside of the UK. Global commerce is not a new thing. The fashion for bringing exotic plants into the UK began as early as the late 1500’s with the renowned ‘John Tradescants’, a father and son bearing the same name and occupations – gardeners, collectors of curiosities and plant importers for wealthy patrons, including Charles I. These exchanges however were at a considerably slower pace; a person can walk into Knepp wearing the same boots that had wandered the pathways of the Bangkok Botanic Garden fifteen hours earlier.
According to Horticulture Magazine the amount spent on gardening products per year is expected to reach £6.5 billion by 2025. Movement of plants within the EU requires the certification of a Plant Passport which “assures compliance with all plant health requirements”, that it is free from particular pests and diseases. But the focus is on the potential harm to plants, not ecosystems – any insect travelling in the soil not listed as harmful to the plant is therefore not required to be assessed. In any other year we would have managed the project as we had planned, growing as many plants as possible from seed in this country to reduce our carbon footprint. Ironically, that same global movement was the mechanism that spread Covid 19 and forced us to take other routes to source the plants.
But we would most likely still have imported some plants, part of Tom Stuart-Smiths garden design to create a resilient ecosystem and maximise opportunities for our native wildlife in hard times of climate change and habitat fragmentation. How significant these non-native insect species will prove is hard to say. Surprisingly few new insects have caused problems in the UK – so far. Even the harlequin ladybird, originally from Asia and publicised as an aggressive invasive when it first appeared in UK gardens in 2004, competing with our 26 native species of ladybirds, is becoming less problematic now that our native predators are learning how to deal with it. Our on-going surveys will hopefully monitor the effects and population growth or decline of these non-natives – something that could prove useful to the horticultural industry and UK ecology in general.
But it is clear these accidental introductions shouldn’t be happening in the first place. In the same way that we are becoming more aware and engaged in what we eat and where it is from, the horticultural industry should afford the same degree of scrutiny to the plants we bring into our gardens. Perhaps it is time for plant passports to be used in a way that will ensure genuine biosecurity and protect our ecosystems?
Moy Fierheller Deputy Head Gardener February 2024
Photos courtesy of Graeme Lyons, Karen Finley, Moy Fierheller
What we’re reading;
Native Farming Solutions OKC (@nfsokc) • Instagram photos and videos
