The locally sourced native species will be planted to protect vulnerable land around the Derwent and Greta rivers to restore the Lake District area by creating a barrier to heavy rain hitting the ground. Floods in November 2009 caused £276m of damage to the area.
Woodland Trust representative Peter Leeson said: "We will be planting several thousands of trees in nine different schemes from Keswick to Workington over the winter.
"They will have long-term benefits for water quality and wildlife."
Environment Agency representative Mike Farrell said willows and hedges would be planted to create barriers to hold back "eroded banks".