The Woodland Trust will invest £4.5m to ensure the 4.5 million trees it plants and supplies over the next three years are grown in the UK from fully traceable seed stock sourced in the UK and Ireland, minimising the risk of pest and disease spread.
It is the largest contract of its kind that the charity has entered into, with native seeds sourced by Shropshire-based seed collector and supplier Forestart from more than 1,000 locations across the UK selected for quality and known provenance.
These are being grown primarily by three nurseries - Alba Trees of East Lothian, Crowders Nurseries in Lincolnshire and Thorpe Trees in Yorkshire. The trust is also in the process of finalising agreements with suppliers in Wales and Ireland.
Woodland Trust director of conservation and external affairs Austin Brady said: "By starting from the beginning of the supply chain we can be confident in the source of every tree we plant, negating the risk of imported saplings bringing in disease, as seen with ash dieback.
"It is crucial for us to lead the way in building resilience in our woods and countryside, and we hope other organisations will be inspired to follow our example."
Some 500,000 trees have been provided to schools and communities during the current planting season as part of the initiative to mark the centenary of World War One.
Wood packaging - Importers urged to comply with regulations
The Forestry Commission has urged importers who use wood packaging in shipments to comply with regulations to protect Britain's trees from invasive pests.
As the weather warms up, the risk that insect pests such as Asian longhorn beetle (Anoplophora glabripennis) can become established increases, the commission warned.
Head of plant health John Morgan said: "Importers will wish to avoid having to destroy, treat or possibly re-export wood packaging material when it represents such a risk. This is costly and inconvenient for the importer and we would much prefer that any wood packaging material was fully compliant."
Plant protection organisations of exporting countries have been asked to ensure that exporters are made of aware of and comply with the regulations.