What would be the female equivalent? Or do you use the male form even when it's a female saying this?
grădinăreasă or grădinăriță :-)
The female form is not accepted though. Neither form you gave... (04-2020)
You should report it. I am not part of Duolingo team :-)
also ”Eu sunt un bun grădinar”
Female gardeners don't exist in Romania ?