"It’s a way of summing up our long-term vision," said the trust. "Focus has changed from creating woodland on our existing estate to other people’s land."
Escalating land prices made this the only way to fulfil its vision of doubling native woodland cover and plant 20m native trees a year in the UK, against 6m at present.
Trust chairman Anderson said: "We realise 20 million trees is a huge task but an increase in tree-planting rates is essential, and we can’t do it alone.
"That’s why the Trust is calling on all individuals and organisations to help rise to the challenge. "The simple act of planting trees unleashes a host of benefits.
"In just 12 years they become beautiful woodland, home to a vast array of wildlife and places where children can play, adults reflect, birds and plant life flourish."