July 20th, 2015

Westonbirt Arboretum’s Tree Team is working with The Duchy College to grow new plants from some of the collection’s oldest and rarest rhododendrons.

Last month Westonbirt welcomed a special delivery of 19 young rhododendrons, from four different taxa, ‘micro-propagated’ and grown for the last four years at The Duchy College’s specialist facilities in Cornwall.

Micro-propagation is a method of vegetative plant production undertaken in laboratory-like, sterilised conditions using petri-dishes and Agar gel. Tiny cells taken from the rhododendrons’ flower buds one to three months before expected flowering were used to grow roots and shoots. One great advantage is that a vast number of plants can be raised from a single fragment of plant material.

The technique means that the team can grow new plants from rare hybrids introduced over a century ago by Westonbirt’s founder Robert Holford and his son, Sir George Holford. The Holfords used selective breeding and seeds collected by famous Victorian plant hunters to create the hybrid varieties, some of which are exclusive to Westonbirt’s collection.

The team at Westonbirt is used to creating and caring for young trees and shrubs at its propagation facilities. 1,511 specimens are housed in the glasshouses, polytunnels, shade house and standing down area at any one time and can remain there from two to five years before being planted out into the collection.

Usually, specimens are either grown from seed collected in the wild (such as on the recent collecting trips to the USA and South Korea), or from techniques such as air-layering. Air layering is when small areas of the branch are wrapped with moss and rooting hormones and sealed in black plastic, convincing the plant that it is underground. The roots are then left to grow on the plant until they are strong enough to be potted. Micro-propagation is a technique generally reserved for very old, more difficult, or less vigorously growing plants.

Westonbirt had its collection of rhododendrons professionally surveyed in 2007. Many were identified then as important Victorian hybrids, and so the programme of getting these rare plants propagated began.

“The rhododendrons we are reproducing are very exciting from an historical point of view; they represent one of the most significant periods of horticultural development at Westonbirt,” said Penny Jones, Propagator.

The young rhododendrons will stay in Westonbirt’s propagation unit for around four years until they are ready to be planted out in the collection.

Tree of the month: July 2015

July 3rd, 2015

Tilia oliveri, image credit Edward Parker

What is the tree of the month?
Tilia oliveri (Oliver’s lime)

Why is it tree of the month?
The beautiful foliage with a pale underside, along with the large flower bract make this species quite distinctive. Soon to flower, this is most definitely a seasonal highlight.

Where can I find it?
The champion grows on Specimen Avenue, whilst there are other mature trees in Acer Glade and on Holford Ride.

Dan Crowley, Dendrologist

STIHL Treetop Walkway: an update

June 29th, 2015

Work has begun on the STIHL Treetop Walkway, which will give visitors an exciting new perspective on trees. The walkway is part of phase two of the Westonbirt Project

It’s all go here at Westonbirt at the moment. The STIHL Treetop Walkway is well underway with most of the foundations complete. The main structure will soon start taking shape when four very large cranes arrive!

The majority of the Walkway is being fabricated off-site; in Yorkshire where the steel sections are being manufactured and in Holland where the timber legs are being machined.

I recently visited Woodspecials in Holland along with Paul Miller from Glenn Howells Architects, Shane Marsh from SH Structures (the steel fabricators) and Susanna Byers, our Interpretation Support Officer, to check progress.

The timber has been sourced from Belgium and Germany and is a mix of Larch and Douglas fir. The legs vary from 2.5 metres up to 13.4 metres in length. This is a picture of me stood next to some of the Larch before machining; this is about 8 – 10 metres in length.

Me by the legs
The log is carefully manoeuvered into the workshop, one at a time due to their size!

STHIL chainsaw
The log is trimmed to size at the end to ensure it fits onto the machine. Once in place the team check if the timber is in its correct position to ensure the straightest section is cut from the log. They do this partly by eye and also using a tape measure and some very large calipers!

Once checked the machine gets going. The timber rotates as the blade runs up and down the length removing the sapwood and creating a perfect smooth finish to our precise dimensions. It was mesmerising watching the timber being machined but also incredibly loud.

The first leg is almost complete
The first leg is almost complete

The first leg is ready for the final touches
The first leg is ready for the final touches. The second one is ready to be machined.

The first delivery of the completed legs will start arriving in the next few weeks. Once here they will be sorted into order, transported to the walkway and then carefully craned into position. This will involve careful manoeuvring over and underneath the tree canopy. Please be aware that we may have to close Skilling hill and parts of Willesley Drive for your safety.

Sophie Nash, Project Manager

A taste of timber framing

June 9th, 2015

Last week, staff and volunteers here at Westonbirt had an opportunity to get involved with the construction of the timber frame for the machinery store element of the new Wolfson Tree Management Centre.

I spent a few days with Pete Eyles and his team, learning more about the process, getting involved in marking out timbers and even having a go at using some power tools and hand tools.

Pete is keen that staff and volunteers have a chance to learn more about timber framing, and dedicated a week of his schedule to hosting a number of us from different teams around the arboretum.

During the time we spent onsite, we worked on timber for one of the gable ends of the building. There were a number of personal highlights for me, including marking out timbers and using a plumb line to make sure the cuts that would be made worked with the natural ‘wobble’ of the timbers they would sit alongside; having a go with an electric morticer to cut a mortice in one of the roof beams of a gable end and using some lovely sharp hand tools to finish a tenon to fit into the mortice joint (no doubt Pete’s team will have cast a critical eye and expert hand over this by now to make sure the work is up to standard!)

It was great to spend time with colleagues and volunteers I don’t usually work with, working as a team to get our heads around some of the tricky concepts involved in timber framing – it’s a surprisingly accurate process which Pete, with his 28 years of experience, made look simple!

Pete’s quest for accuracy is for good reason. As well as giving the building a neat and tidy finish, the junctions of the building are made from galvanised steel – these parts are made very accurately, and the team have to ensure the wooden components will fit together with them perfectly.

Timber framing may be an ancient skill, but a structural engineer is involved the whole way through the process, specifying amongst other things the dimensions of timber and the grade, or quality, which is used. Much of the timber for the machinery store is of the highest structural grade possible and, we’re proud to say, a large proportion of this comes from Westonbirt, removed as part of the routine management of the tree collection here.

Take a look at the picture gallery below to see images from the course.

It is anticipated that the first of the gable ends will be raised into position very soon. Watch this space for an update!

Gina Mills, Marketing Support Officer

See it, smell it, touch it, taste it!

June 8th, 2015

The role of the Community Inclusion team is to enable a greater number of people from under-represented groups to experience the arboretum and to connect with trees. Funded by the Heritage Lottery Fund, Community Youth Officer Karen Price is working with young people so that they can discover, explore and enjoy the arboretum, either as part of an organised group or as individual visitors.

As an internationally renowned tree collection, people come from far and wide to experience the magnificent sights the arboretum has to offer. From spectacular spring blooms to bursting autumnal colour, the arboretum can certainly give a feast for the eyes for all our visitors enjoying a walk in the woods. And surely we’ve all got a favourite tree at the arboretum – our curator’s is the paper bark maple at Down Gate, whilst for me I’m torn between the White barked Himalayan Birch on the downs and an old, dead oak in the coppice coup, although I think deep down the oak wins. But how many of us have a favourite sound, or smell?


The community youth team have been developing activities that use the senses to explore the arboretum through sight, sound, smell, touch and taste. And not just the trees, magnificent though they are, but also the habitats they create and the wildlife
that lives in, on and beneath them.

Restoration work in the coppice coups has created sunlit clearings where bluebells and wood anemones flourish, creating a carpet of colour that entice groups in. They crouch down and look closely at the ground where empty hazelnut shells can be found, each one presenting a clue to the identification of what ate it – split in half for a squirrel or a nibbled round hole for a wood mouse. Then they will find a comfy stump and sit a while and to listen for a greater spotted woodpecker drumming out his call, or even a hungry tawny owl out and about during the day.

In the wider collection groups can feel the textures of the bark; the spongy redwoods, the papery birches and the twisted sweet chestnut. They have found the cones, held them, smelled them and flicked the scales of Holford pine cones with their nails like a thumb piano to make a tune.

They can also smell the landscape of a working woodland. Freshly mown grass and wood smoke, wild garlic and pine resin. Found a fallen eucalyptus leaf and crushed it between their fingers to release the scent. Then sat a while with a cup of nettle tea, or nibbled on a hawthorn leaf (once known by children as bread and cheese and apparently has a mild nutty flavour, but mainly it just tastes of leaf).

Although enjoyed by all, the sensory activities have been particularly engaging for young people with specific needs, particularly autism. In recent weeks we have been working with groups of young people with varying degrees of autism on a repeat visit programme, and have been piloting activities that enable participants to explore and learn about the arboretum at their own level of understanding and speed by engaging with all the senses. Our next project is to make a series of glockenspiels from coppiced hazel to develop creativity (as well as tool use skills) and a Victorian plant hunter’s collection chest which will enable young people with limited mobility to experience the sensory woodlands in a physically accessible way.

Karen Price, Community Youth Officer

Tree of the month: June 2015

June 2nd, 2015

Styrax japonicus snowbell tree credit Gina Mills
What is tree of the month?
Styrax japonicus, also known as the snowbell tree.

Why is it tree of the month?
An ornamental beauty, the white, bell shaped flowers which hang beneath the branches are not to be missed.

Where can I see it?
Specimens of varying ages grow in both the Old Arboretum and Silk Wood. One close to Savill Glade always catches the eye from Main Drive, where it grows alongside the also lovely S. obassia.

Dan Crowley, Dendrologist

Celebrating volunteering at Westonbirt

June 2nd, 2015

Although we value and thank our volunteers on a daily basis, Volunteers’ Week provides an opportunity to do this publicly!

Volunteers are deeply embedded in the fabric of Westonbirt and the arboretum flourishes on their commitment. They are passionate and enthusiastic ambassadors for Westonbirt, championing community spirit and connecting visitors to the importance of trees in our lives – whilst having a thoroughly good time themselves.

Last year volunteers gave almost 25,000 hours to Westonbirt in so many ways, here are a few of the ways they help:

  • Leading 269 guided walks for 2,800 visitors (their feedback showed a 95% enjoyment rating)
  • Travelling over 2,750 miles to give 54 external talks to over 1,800 people
  • Taking 66% of Friends membership subscriptions at the welcome desk
  • Helping to propagate 4,000 seeds, cuttings, saplings and plants
  • Maintaining 18 sections of the arboretum (there are 60 in total) including 3000 trees/cages
  • Labelling 1,891 trees – 12% of our collection
  • Recording 428 butterflies (20 species), and 330 bumblebees (11 species)
  • Engaging with over 34,500 participants through schools visits and family events
  • Broadening Westonbirt’s reach to the local community by involving:
  • 232 young people (10-19yrs) from 17 organisations
  • 188 people in facilitated visits to Westonbirt
  • 274 people in offsite outreach programmes
  • 111 people in coppice woodland management
  • IMG_7354
    We send a huge ‘thank you’ to all our volunteers and wish them many more years of happy volunteering with us – Westonbirt wouldn’t be the same without them.

    Cheryl Pearson, Volunteer Manager

Westonbirt Project update

May 21st, 2015

Fundraising for Phase Two of the Westonbirt Project is now complete. Work has begun on the STIHL Treetop Walkway and the Wolfson Tree Management Centre, which will give visitors an exciting new perspective on trees and allow us to better care for the arboretum’s important collection.

Temporary road
Work is underway on the STIHL Treetop Walkway and contractors, Speller Metcalfe, have been creating a temporary stone access track to limit the impact of the construction vehicles. The access track will be used by mini diggers for the foundations, and for dumpers and the crane. Once the walkway is nearing completion they will remove this track and reinstate it with top soil.

Please keep your dog on a lead
During the construction of the Treetop Walkway, an area around the work will be designated as a ‘dogs on-lead zone’ – you’ll find this construction zone marked on the map in the summer edition of the Westonbirt Magazine and in the summer seasonal guide leaflet, which can be picked up from the Welcome Building.

We’d like to say a big thank you to all of our dog-walking visitors for abiding by signs requesting that dogs are put on leads for a short time during their visit, thus making sure the arboretum remains a safe an enjoyable place to visit and work in as we see these exciting changes take place onsite.

Over at the site of the Wolfson Tree Management Centre, the carpenters have used a 500mm x 300mm piece of timber to create the first “king post”, one of five in the new machinery store.

This image shows two members of staff from Westonbirt’s Tree Team looking into the construction site, and what will eventually become their new base at the arboretum. This is where visitors will be able to look through at the new viewing area which will bring them closer to the work we do to care for our trees.

This image shows timber sourced here at Westonbirt and from the Longleat estate laid out as fabrication gets underway on the timber frame.

Sophie Nash, Project Manager

Tree Management Centre and other updates!

April 30th, 2015

Work is currently underway on what will become the new Wolfson Tree Management Centre. The new facility will provide all that Westonbirt’s expert tree team needs to manage the tree collection. There’s also a lot of other work going on as we start the construction of the STIHL Treetop Walkway and continue our programme of boundary restoration.

The timber for the Wolfson Tree Management Centre has been graded to test its structural strength. This is based on a number of factors including the type of timber, the number of knots and where the knots are.

If you’re around Didmarton Grove in Silk Wood next week, you’ll see more timber being milled by Alastair Williams.

Graded timbers

The timber framers have moved some of the graded timbers into the new yard. They have laid these out in position so they can prepare the ends of the timber ready for joints and connections.

Laid out timbers

Elsewhere, Speller Metcalfe have been on site carrying out additional surveys for the STIHL Treetop Walkway. Work is going on behind the scenes to finalise the details ready for fabrication so we can start digging holes for the foundations.

The Walkway legs are being machined as we speak and there will be more to follow on this in the next blog!

You can also expect to see new metal estate fencing going in during May, as we replace the timber post and rail fencing which runs up the hill from Skilling Gate and along the access road towards the Forestry Commission offices. The new fencing will match the traditional estate fencing you see as you drive into the arboretum.

Sophie Nash, Project Manager

Tree of the month: May 2015

April 23rd, 2015

Acer amamiense

What is tree of the month?
Acer amamiense

Why is it tree of the month?
The new foliage flushes beautiful shades of purple. It really is a treat. The new growth is also rather hairy!

Where can I see it?
We have six plants. Three in 2050 glade, two around Savill Glade and one at the south end of Palmer Ride.

Dan Crowley, Dendrologist

> Find the locations of these plants using the Interactive Map