Lady Tighe died when Blachford was young, and her father went on to marry the heiress Margaret Theaker, through whom she had a half-brother, Thomas, and half-sister, Barbara.

She was raised in the Church of Ireland, but was inspired to find a new religion at age of 17, leading her to read extensively on religious matters and to "renounce the world.

She attended the Whitefriar Street Church, and given her position in society was a prominent figure in the Dublin Methodist community.

Blachford wrote a number of religious tracts and translated the life of Jane Frances de Chantal, founder of the Visitation Order.

[citation needed] She did not approve of her daughter's marriage to her first cousin Henry Tighe, and strongly disapproved of her frivolous lifestyle.

Regardless, she spent a large amount of her time in England with her daughter, nursing her through a long illness and eventual death of tuberculosis in 1810.