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26 Nov 2021

Pitmedden and the box dilemma

Written by Chris Wardle – Gardens and Designed Landscapes Manager, Aberdeenshire and Angus
An aerial view of Pitmedden Garden, revealing the 6 distinct and colourful parterre gardens. A large stone house stands at the far end of the garden with tall trees around the perimeter.
Box blight is one of the greatest threats to our historic gardens, in particular at Pitmedden in Aberdeenshire. We need to begin a process of change to mitigate the risks.

Many of the great gardens in the United Kingdom rely on planted structures to create divisions and sections in the design and their layout. These structures help to define the themes of a garden, creating the design backbone. Many are well known and often photographed, such as the long broad walk hedges of Hidcote Manor in Gloucestershire or the intimate garden rooms of Sissinghurst Castle Garden in Kent – even the towering old monolithic hedges of Crathes Castle and Powis Castle. These structures have traditionally been planted using hedges of various sizes, species and shapes so that the designs can be defined and shown off to great effect.

The ultimate example of planted structures comes in the form of a ‘parterre’, a French word that literally means ‘shape on the ground’. A formal parterre usually consists of small hedges separating either coloured gravel or colourful planting to create elaborate designs to wow and amaze the viewer. Some of the greatest examples can be found at Versailles in France, created by King Louis XIV in the late 1600s as a display of incredible wealth and power over the environment. The intricate designs took many hundreds of gardeners to keep in pristine condition. The fashion was thus created and copied across Europe for almost a century. Trade routes brought the garden style across the North Sea to Scotland, where there were recreations throughout the country, as well as across the Irish Sea to some of the great estates in Ireland.

An aerial view of an elaborate parterre, shaped in the form of a coat of arms. Intricate lines of box hedging form the outline, filled with pale gravel or bedding plants.
Pitmedden’s coat of arms parterre

Fashions come and go, adapt and change, but the composition of parterres has persisted for generations and can still be seen today in the style of modern gardens who take their cue from the past and reinterpret it for a modern audience. Above all, the use of small hedges – usually comprising boxwood (Buxus sempervirens) – is key, but here lies the dilemma for an entire generation!

Box blight

For the last 20 years box blight has been an increasingly problematic issue for gardens across the world. Box blight is a disease of the box leaves and stems caused by the fungus Cylindrocladium buxicola, although it doesn’t kill the roots of box plants. It largely affects Buxus spp. (box) in the UK, but other plants in the Buxaceae family are also susceptible.

Affected box plant species typically show the following symptoms:

  • Leaves turn brown and fall, leading to bare patches.
  • Black streaks and dieback appear on young stems.
  • In wet conditions, the white spore masses of the fungus may be seen on the under-surfaces of infected leaves.
A close-up view of a small, individual box plant affected by box blight. Its lower and middle leaves are brown and withered.
Box blight (Cylindrocladium buxicola)

Unfortunately, this is not the only issue for our box plants on the horizon. As the climate starts to warm, we now have the box tree moth (Cydalima perspectalis) starting to get a foothold on plants in southern parts of the UK, and soon it may well spread further north. Whilst this is likely to be some time away, it’s an indicator of the increasing threats that all plants are facing and the speed of change in the natural environment. It shows us how nimble we have to be in our response in proving that we have the ability to care for and protect our key conservation assets in the garden environment.

Why does this matter?

At the heart of our gardens policy is the basic question of ‘what makes this garden special?’ In some cases, this can be hard to answer in a simple way and is regularly debated amongst the garden managers; in other cases, it is easy to identify. In this specific case of Pitmedden Garden, it is incredibly easy: the box hedges.

So what happens when you take away the central design point and ethos of a garden? What do we have left? How do we maintain the integrity of the original concept whilst change is forced upon us? This is the dilemma of what is about to happen at Pitmedden and its Great Garden parterres. They are under attack and we can’t stop what’s happening. For the last 15 years box blight has attacked the box hedges at Pitmedden. They have been sprayed regularly as part of a management regime to keep the fungal attacks at bay. But this is an unsustainable process and in the modern world it is becoming increasingly difficult to justify. There is now much more awareness of the environment and our activities, and how we cannot place additional burdens on it by using poor practices. We have to change – but the costs may be heavy.

Recently, whilst replacing a small section of box hedge that was failing, Pitmedden’s Head Gardener Scott Smith took the below photo of the root system of the plants. He was shocked. The build-up of copper residues (one of the active ingredients in the antifungal sprays) was clear to see in and around the base of the plants. This photograph begs the question: what are we doing to the soil if this is what’s left?

A close-up view of a box plant that has been slightly uprooted from the soil bed. The clump of roots is covered in a thick, coppery-green residue.
Copper residue around the roots of a treated box plant

A meeting was held with the Trust’s Head of Heritage Gardens (Policy) and other Garden Managers to discuss the way forward, debate the issue and make a plan of action. Universally, it was agreed that the activity had to change, as would our management of the process to maintain the design ethos. Recently, the Royal Horticultural Society started to trial alternative plants that may be able to replace the ubiquitous box. Whilst many have some merit, the trials were carried out in the south of England and so those alternatives may not thrive in the Scottish climate. Therefore, on site at Pitmedden the garden team have been undertaking their own small-scale trials of alternatives, and they have had some interesting results.

A trial bed in a garden, surrounded by paved paths. Inside the bed grow many different types of shrub and box-like plants.
The Royal Horticultural Society trial

The key decision has been taken that the overall design of the parterres will stay the same and that the plants will be gradually changed, over time, to build a resilient but diverse range of plants. This should create the same design effect whilst using a range of colours and textures. The change will take time but, once it is finally implemented, it’s hoped the garden will have the same feel and integrity as it has had for the last 60 years. We hope this process will take around 10 years. A key consideration for the whole task is one of reversibility; at all times the changes should be brave but also carefully considered. The garden team will be able to learn from the process as the task is gradually completed.

Most importantly, we will be able to use the lessons learned to help inform decision making at other National Trust for Scotland gardens as well as at private and our stakeholder gardens.

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