Last week I was lucky enough to go on a three day course at the Plant Conservation Centre (PCC) in Devon. The PCC is a specialist propagation facility for the National Trust and its main aim is to propagate the rarest and most threatened plants from around the UK. The National Trust’s gardens contain one of the most important and diverse collections of cultivated plants in single ownership anywhere in the world and the collection includes specimens that were brought to the UK centuries ago from all corners of the globe by intrepid plant hunters.
As well as all the serious stuff we spent “Wiggy Wednesday” at the PCC looking stupid to raise money for children’s cancer charity Clic Sargent
The PCC was initially set up as a response to the Great Storm of 1987 when thousands of fallen and damaged plants suddenly needed propagation and, through the skills of their staff, the majority of important specimens were saved. The role of the PCC is becoming more critical as new plant diseases arrive into the UK and long term climate change threatens many plants. One plant the PCC are currently helping to propagate is wild asparagus – once a plentiful plant in the UK but now, due to changes in land use, classed as an endangered species.
Due to the nature of its work the PCC operates under controlled, bio-secure conditions, meaning that every possible precaution is taken to protect the plants on site from pests and diseases. The first step when new plants are brought to the PCC is for them to go into a quarantine area which consist of 2 greenhouses where plants are left for 6-8 weeks and monitored for the presence of any pests and diseases.
The quarantine area
Step 2 is that when entering the nursery any cross contamination is avoided by scrubbing and disinfecting footwear (which may contain soil-borne disease) by using brushes and footbaths.
No muddy boots allowed!
New plants start their life in the propagation house which contains normal potting benches, mist units, a micro-propagation unit and a hot pipe area for grafting new material onto root stocks.
The propagation house
Here cuttings are taken and start off in small plugs. We were excited to spot one of the plants we sent to the PCC recently from Chartwell – Kalmia latifolia ‘Clementine Churchill’ – a cultivar named after Sir Winston’s wife. Whilst we have surviving plants in situ at Chartwell they are not in the best of health and this means that taking successful cuttings from them is challenging.
Each plant has a unique number so that it can be entered and found on the National Trust database. I had never seen our Kalmia in flower before.
Sharing the propagation house with our Kalmia was a row of lime trees that have been propagated to replace the magnificent lime avenue at Stowe in Buckinghamshire.
The original lime avenue at Stowe was planted in 1720 by Charles Bridgeman, a predecessor to Lancelot “Capability” Brown and the original trees are near the end of their life expectancy
The PCC does not use any chemical sprays to control pests and instead relies on biological pest control methods, meaning that natural pests are encouraged to pray on unwanted aphids and insects.
Pots of the marigold Tagetes minuta, sweet alyssum and fuschia are simply placed in the doorway of the greenhouses and attract aphids away from other plants
Another plant that was doing a good job at controlling sciarid fly was Pinguicula moranensis which was placed between rows of cuttings.
This genus of carnivorous plants use sticky, fleshy leaves to lure, trap and digest insects
Once newly propagated plants are ready to be potted on they are moved to the growing on house and then to polytunnels before reaching the main growing house.
Checking for pests in one of the polytunnels
In one polytunnel we saw Gladiolus brenchleyensis which was one of Gertrude Jekyll’s favourite plants. It had become so rare that it was thought lost to cultivation until spotted in a garden in the Isle of Man around 5 years ago. The PCC are now building up a stock of the plant.
Once plants have grown large enough to be moved into 3 litre pots they are transferred into the main growing house.
The main growing house has automated irrigation and automatic fans to keep plants at the ideal temperature
In the main growing house we found another plant with a connection to our property at Toy’s Hill – Rosa ‘Octavia Hill’.
Rosa ‘Octavia Hill’ named after one of the founders of the National Trust
The unit at present can handle approximately 12,000 plants at a time
One particularly famous tree that the PCC are propagating that we saw in the main growing house is an apple tree called Malus domestica ‘Flower of Kent’. While this cultivar is commercially available the one at the PCC derives from a cutting taking from the very same tree that dropped an apple on Sir Isaac Newton’s head and inspired his theory of gravity. The tree itself is still alive after more than 350 years but as this is well beyond the usual life expectancy of any apple tree the National Trust is looking to the future to make sure a genetically identical tree can take its place and continue the story.