Mr Goldsworthy said Labour's plans were "speculative and risky" and based on a 20% increase in borrowing after inheriting "healthy finances" from the Conservatives.
After touring the home, take a stroll through the sculpture garden, with works by Andy Goldsworthy and Claes Oldenburg, and two slabs of the Berlin Wall.
"It seems fitting that the Solway Centre is opened in the part of the world where the word 'environment' was created by Carlyle in 1826 and which has sustained creativity from the 'ploughman poet' Burns to modern land artists Jencks and Goldsworthy, " she said.