It appears that the Durham concerts were in alternate weeks to those organised by his friend Charles Avison in Newcastle, where Garth played the cello.
Garth's fame spread and he taught music to leading families in the region, as well as giving organ recitals.
He died at his home, Cockerton Hall, on 29 March 1810 and was buried on 5 April 1810 in the north aisle of St Cuthbert's, Darlington.
Garth is chiefly remembered for his eight-volume edition with English text of The First Fifty Psalms Set to Music by Benedetto Marcello (1757–65).
Gerald Finzi took an interest in his music, among other neglected British composers of the 18th and 19th centuries whose work he sought to have published in modern editions.