Our work at Trengwainton Garden

Inside the bee house at Trengwainton Garden, Cornwall — Inside the bee house at Trengwainton Garden | © National Trust Images/Andrew Butler

At Trengwainton Garden, we’re working hard to protect the flora and fauna from disease. Discover how we’re preserving the internationally renowned collection of plants and the work we’re doing to protect the bee colonies in our care and ensure they remain healthy.

Protecting the bees

Colonies of bees have been decimated by the Varroa mite (V. destructor), which sucks the blood of adult bees and infects young bees still in their pupal stage. The infestation weakens and shortens the bee’s life and if left untreated, can wipe out whole colonies.

How are we helping?

We’ve restored the Victorian bee house in the orchard to full working order and it houses two colonies of bees. These brick-built buildings are common in northern European countries, but unusual in Britain.

We also have a number of hives behind the scenes as well as those that make their homes in the hedges and underground. We’ve received expert advice and support from an independent member of the British Beekeepers Association, who’s taught one of the garden team the basics of bee keeping and how to look out for parasites like the Varroa mite.

Encouraging bees

In the kitchen garden we plant flowers and vegetables side by side, in order to encourage the bees and during the winter months we ensure the colonies have sufficient food by feeding them with a sugar solution.

Signs of the fungal disease, Phytophthora ramorum - also known as Sudden Oak Death on rhododendron at Trengwainton Garden, Cornwall — Sudden Oak Death disease on rhododendron at Trengwainton Garden | © National Trust Images/Ross Hoddinott

Saving plants from disease

When Trengwainton Garden was gifted to the Trust in 1961, it was the significance of the plant collection that made it so special. Now with the threat from a virulent disease, it’s science that’s coming to the rescue.

Why it’s now under threat

Phytophthora ramorum (and the Cornish strain, Phytophthora kernovii) is an aggressive, fungus-like disease, that’s causing serious damage to a wide range of ornamental plants. It was originally known as Sudden Oak Death, because of its devastating effects on native oaks in the USA, but now affects a whole range of species.

Several rhododendrons, magnolias, camellias and pieris have died because of the disease and those that are left, remain vulnerable to infection.

How we’re fighting back

Duchy College Rosewarne have used micropropagation techniques to save some of the key rhododendron, magnolia and eucryphia.

The technique involves taking small pieces of plant material, sterilising them in diluted bleach then growing them on in a nutrient jelly with added plant growth hormones, which allows manipulation of the way the plants grow.

It’s costly and time consuming – it can take a minimum of two years to produce rooted plantlets – but many key plants have been rescued from certain loss.

The Noah’s Ark of plants

When the plantlets are old enough, they go to the Plant Conservation Centre, which was set up to maintain and enhance the plant collections in Trust parks and gardens.

In this state-of-the-art centre, the plantlets are weaned off their nutrient jelly and into compost and at around five years of age, they’re strong enough to be transferred to carefully chosen gardens.

An international endeavour

The Plant Conservation Centre partners with gardens all over the world, to give the plants the best chance of thriving in a disease-free environment, once they’re reintroduced outdoors.

In recent years, the control and containment of Ramorum disease has become the biggest challenge which we must overcome, along with the ongoing changes to the climate.