The Urban Jungle: A Survival Guide

Friday 17th March 9.15am – 4pm

The Banks Building, Royal Botanic Gardens, Kew

On 17 March 2017, the LGN’s seminar took place at the world famous Royal Botanic Gardens, Kew. The seminar focused on the challenges facing our gardens today and how biosecurity can help us.

The seminar was a great opportunity to network with fellow professional gardeners and there was time to catch up with friends and colleagues and look around the beautiful gardens. The conference finished at 4pm allowing members an hour to explore the Gardens before it closed.

Seminar Speakers

Bartlett Tree Expert’s head scientist Glynn Percival took us through the current pests and diseases threatening our trees; Ian Wright from the National Trust and David Slawson from OPAL (Open Air Laboratories), described the best methods to ensure biosecurity in your garden. In the afternoon, Sven Seiffert, head of horticulture at London Zoo, regaled us with tales of his unique urban jungle. Chairman of the London Parks and Gardens Trust (and Head of Landscape and Horticulture at Wakehurst Place), Ed Ikin discussed London gardens which make attracting wildlife their mission.

LGN 2017 Seminar: A Personal Perspective from the Audience

Written by Oliver Miller, April 2017

Early in his talk, Ian Wright offered us a cautionary note, albeit jovially: “Be careful how you speak to the press about pests and diseases.” He was advising from personal experience.

I think it would have also been fair for the audience to say to this year’s speakers: “Be careful how you speak to gardeners about pests and diseases.”

Because as gardeners, going to a seminar on the latest threats to our planet’s plants can be a bit like visiting the hospital for uncertain test results.

However, it appears that gardeners like to face their deepest concerns head-on, as this year’s seminar, (centering around that very theme) saw a record-high attendance of over 150 of us at Kew’s splendid Sir Joseph Banks Building.

If you did not make it then please fear not, for of the many good feelings that I took away with me this year, the overarching one was encouraged. During the train journey home I reflected on this feeling, and noticed that within the structure of this word is the meaning ‘to make braver’.

It seemed to me that this year’s topic acted as a lens through which all of the speakers were able to focus upon four deeply positive encouragements.

This was a reassuring surprise given the broad range of content delivered. Glyn Percival talked about the cutting-edge technology available in keeping trees pest and disease free. David Slawson and Ian Wright talked about the good work of OPAL and the National Trust in embedding plant healthcare into our teams’ daily horticultural practices. Sven Seiffert talked about how to combine horticulture with zoo keeping. Ed Ikin talked about the mission and powers of the London Parks and Gardens Trust.

But the four encouragements that I took away from all of our authoritative speakers in regards to combating these challenges were:

  • Use creative, prejudice-free methods
  • Empower plants to look after themselves
  • Promote a diversity of species in planted spaces
  • Make decisions that are evidence based

Good things happen when we are true to these principles. Here are some examples of how these were conveyed in their talks:

Creative and Open Minded Methods

Glynn confessed readily his penchant for ‘weird and wonderful’ ways of protecting trees, firing off a frenzy of tried and tested methods including willow-content mulches, biochar soil improvers, branch vacuum cleaning, flight drone inspections, refined sugar feeds, tree injections and vaccinations, use of pheromones, ultra low volume spray devices, (sometimes involving spraying oak trees blue). He acknowledged the prejudice that many of us have towards some of these kinds of treatment of beloved trees, but passionately believes that they must be preferable to the traditional alternative of “sanitation,” which he affectionately names as the “slash and burn” method.

David and Ian explained that the National Trust now use the term ‘holding back’ for plants that previously would have been described as being ‘quarantined’, which has been recognized as an off-putting term for many. They also told us about the new Plant Health Award Scheme that the National Trust has introduced to further motivate gardeners, where previously such efforts may have gone overlooked.

Sven highlighted the unlikely good fortune of the London Zoo’s car park bramble patch being a hedgehog haven, and reminded us that we need not wait for species to become endangered before we take an active interest in their welfare.

Ed championed sites around the city that might usually be considered as unsuitable for successful horticulture, such as in and around the built up areas of the Barbican, but showed us how to tap into their potential. For the right plants, even crushed brick can be the perfect growing medium.

Plants Empowered

Glynn calls tree vaccinations ‘plant defense activators’ (PDA’s). He explained that what makes a disease successful is the ability to attack a tree without its detection; by the time it does and we do it is too late. PDA’s switch on the tree’s defenses early, just as do vaccinations for humans.

Ian and David talked about a ‘continuum’ of care that must happen from the sourcing of the plants to the introduction of them into our gardens to the on-going maintenance of them, with good healthcare practices being fully embedded into our everyday gardening work in order to ensure that their needs are always kept as a priority.

Throughout Sven’s presentation the Zoological Society for London’s tagline appeared at the top of each slide: ‘Let’s Work for Wildlife.’ As gardeners isn’t this exactly what we are doing for plants, animals and humans all the time? It’s a constant process of balancing of interests, and the line between those interests can (and sometimes should) easily blur.

Ed outlined the ideas contained in the Grime Theories, which describes three main types of plant: competitors, stress tolerators and pioneers. By thinking of them in this way we can provide them with conditions that match as closely as possible their natural environments.

Diversity of Species

Glynn explained that many pests and diseases are species specific, so our gardens are far more vulnerable to larger scale losses the more monocultural our planting is. He uses the plating rule of no more than: 10% same species, 20% same genus, 30% same family, for any given garden area.

Sven described biodiversity and conservation as one of the three main aims of ZSL horticulture, which he places side by side as factors that mutually feed into one another.

Ed outlined the seven tiered design of Forest Gardens, which encourages the gardener to think about the larger picture of the garden’s biosphere, from root to tree-top, when generating and looking after a self-sustaining, productive system of variety-rich plant and animal life.

Evidence-Based Choices

Glynn spends lots of time working from a laboratory, using scientific methods to carry out research based testing of products and techniques. Results are charted and graphed, allowing us to make informed decisions about the wider impacts of our intervention choices.

Ian and David talked about Conservation Performance Indicators (CPI) for conservation work, a standardised system of monitoring and scoring how well flora and fauna is being cared for in National Trust Gardens in a way that is embedded into all practice from the beginning.

Sven mentioned that the best plant ‘exhibits’ in zoos are designed off the back of in situ research, what works for the animals or plants is not always what we would imagine. He reminded us that talking to other gardeners is one of the most important and effective ways of acquiring the evidence we need to make good gardening choices.

Ed explained that the London Parks and Gardens Trust holds an impressive inventory of the culturally significant garden sites across London. Having such a record is a firm basis and reference point for future decision-making in regards to the care and development of these sites, and is perhaps one of the big factors why the LPGT has statutory powers in regards to what happens in them!

We were also lucky to hear from Perennial about the good work that they carry out on behalf of professional gardeners who are hit by hard times at any stage in their careers, and were urged as gardeners to spread the message throughout the industry of the services they freely provide.

Excitingly at the end of the day, newly appointed Chair of the LGN Committee, Claire Midgley-Adam launched the LGN’s brand new logo, website and social media forums. Her core encouragement to us all was: let’s get talking.

As professional gardeners, we need to keep sharing our horticultural findings with each other and beyond if we are to keep our plants safe and strong for a long time to come.

Event Photographs