Project: Street tree renewal in Welwyn Garden City
Client: Welwyn Hatfield Borough Council
Requirement: In excess of 300 semi-mature trees, to be supplied over a period of many years
Date: 2008 – ongoing
Project Manager: James Hillier
Welwyn Garden City, founded by Sir Ebenezer Howard in the 1920’s, is the UK’s second ever ‘garden city’, designed to blend together city and nature. As such, it contains a number of beautiful vistas where trees are a focal point of the view.
With many of the planting schemes now several decades old, Welwyn Hatfield Borough Council (Welwyn HBC) put in place a long-term strategic plan to renew a number of street trees schemes across the town. The main client objectives were – and remain to present day – to respect the original layout and species choice of the trees, as selected over years since the town began. Practically, this means living with declining schemes until they reach the point where the overall effect is compromised and the last trees are felled and the whole scheme, or avenue, is replaced. Whether a road has reached that point is determined by tree officers on a year-by-year basis.
A selection of the key tree varieties chosen for this project included:
An ideal Cherry variety for residential areas and narrow streets.
An introduction by Captain Collingwood Ingram, who was the leading western authority on Japanese cherries. This variety had historical significance to the city, as one of his first introductions that adorned the garden city in its early years. The flowers are a magical pink in late winter, heralding the new season just around the corner!
Liquidambar styraciflua ‘Worplesdon’
A majestic form of Liquidambar with strong pyramid shape and striking yellow, orange and deep red autumn colour.
Ulmus ‘New Horizon’
A relatively recently developed elm variety that is resistant to Dutch elm disease.
Fagus sylvatica ‘Dawyck’
An upright form of Beech. Recommended by Hillier for the Parkway Close scheme as an alternative to the previously planted Lombardy Poplars. A longer-living species that offers the tall spire required in maturity for this iconic area of the town.
The brief involved four key tree planting schemes throughout the town:
1. Digswell Road
The entrance to the town from the north comprised two sections and three distinct planting layouts. These planting layouts were:
- A formal layout either side of the road of sets of Prunus sargentii interspersed with Acer campestre. The composition was declining badly, and though the Acers were wonderfully mature only 36 of 156 of the Prunus remained.
- Knightsbridge roundabout with 10x Silver Birch.
- A continuation of the formal layout, but with Prunus Kursar replacing Prunus sargentii
The southern end had an avenue of 30x Horse Chestnuts in early maturity that had succumbed to ‘bleeding canker’ in the years running up to 2010. All needed to be felled and, eventually, replaced with an alternative.
3. Parkway Close
An area first planted in the 1920’s with a formal pattern of Norway Maples, Lombardy Poplars and Ornamental Cherries. One Maple had been lost, the Poplars had reached overmaturity and were beginning to decay – around 40% had been felled – and the Cherries were also overmature with some having been felled.
4. Fearnley Road
This classic residential road had retained its specimen Silver Birch trees at both entrances, but needed a new avenue of trees within the road, as over 50% of ornamental trees had been lost.
Production & Progress
For this project, we needed to grow trees in large numbers. In addition, it was essential we were able to reserve trees from the same stock, e.g. Prunus sargentii, Liquidamber, for future call offs. The Welwyn team were able to select the trees they required during production and made annual visits thereafter to check on their progress.
Delivery & Planting
With this being such a long-term, strategic project, deliveries and planting have taken place in many stages over the years and are still ongoing.
1. Digswell Road
2008: 10x Silver Birch replanted.
2012-13: 156x Prunus sargentii selected from Hillier’s field-grown stock in June 2012 and planted during winter season 2012-13. Hillier also sourced 100x Prunus ‘Kursar’ as bare-root stock at 150cm high, grown on our nurseries to become 10-12cm container-grown trees.
2014: 64x container-grown Prunus ‘Kursar’ planted in winter season. Remaining 32 held back for future planting.
2017-18: Extras reserved from the 2012 Prunus sargentii stock are still being planted to replace vandalised trees.
2010: Phase 1 – 5x Horse Chestnuts felled.
2013: Phase 2 – 8x Horse Chestnuts felled. In June, 13x Liquidamber styraciflua ‘Worplesdon’ were selected from our field tree nursery, with more
reserved to allow for future losses. The 13 were planted in winter.
2016: Phase 3 – 14x Horse Chestnuts felled. 14x Liquidamber trees planted that winter.
2018: Phase 4 – The final 3x Horse Chestnuts will be felled in summer and replanted in winter with the same 2013 Liquidamber stock held on our nursery.
3. Parkway Close
2016: In June, replacement trees were selected from our nurseries. In August, the entire close was felled. In winter, the felled Lombardy Poplars were
replaced with Fagus sylvatica ‘Dawyck’ (Fastigiate Purple Beech), the Norway Maples with Ulmus ‘New Horizon’ and the Cherries with another white-flowering variety.
Ongoing: Hillier have reserved the same cultivars and sizes of stock as selected in June 2016 to provide replacements in event of losses through natural causes or vandalism in future years.
4. Fearnley Road
2017: All existing ornamental trees felled.
We bespoke pruned a number of trees at the request of the client, leaving the clear stems lower than is our standard practice. This was possible to achieve because they engaged with us at an early stage, allowing us to grow and prune trees in this desired manner.
It is particularly rewarding to be involved in such an iconic tree planting project. It has been very successful to date, with Welwyn HBC able to secure future funding for the project as a result of the positive results of the first phases. Feedback on the newly planted trees has been very positive from both residents and local councillors.
The crucial elements in ensuring a successful outcome for this major strategic venture have been detailed project preparation and a continued focus on the core values of the project.
- Ability to work as a long-term strategic partner
- Provision of a wide variety of trees to suit a number of different planting schemes and requirements
- Flexibility to reserve and keep stock growing on our nurseries for many years to provide future replacements as needed of the same type
- Ability to source specialist varieties and grow on in containers to the required specification (e.g. Prunus ‘Kursar’)