[2] She married John Hardcastle, a grocer and tea dealer in Birmingham, in January 1792, but as a consequence of illness, bereavements, and the failure of her husband's business, the couple returned to Derby with their two children.
To support the family through her husband's continuing ill health, she ran a day and boarding school for young ladies from at least 1796 until the 1830s,[1] and she also gave classes in botany and illustration.
Through Francis Boott, the husband of her younger daughter Mary, Hardcastle was introduced to James Edward Smith, founder of the Linnean Society of London.
[2] A manuscript including eight watercolours of flowers and fungi was purchased in 2021 by Derby Museum and Art Gallery with funding from Arts Council England / V&A Purchase Grant Fund as well as the Derby Museums' Friends group.
In addition to the paintings, it records her observations on meadow saffron and the timing of flowering in autumn but apparent seed-set in spring.