After finishing his studies at Clapham Grammar School in south-western London, he was commissioned as a midshipman in the East India Company Merchant Navy, serving from 1836 to 1845.
After this period at sea, he entered into business with his father who ran his own farm and was land agent to William Cavendish, 6th Duke of Devonshire for the Lismore Castle estate in Ireland.
He practised law in the offices of Alexander Hutchison Lunn at Montreal until 1858 when he moved to Drummondville and established a large farm, as did his father.
Aged 82, and having celebrated his golden wedding anniversary with a family reunion sevens week earlier, he died and was buried in the cemetery at Knowlton.
Hemming was elected to the Legislative Assembly of Quebec as a Conservative in the Drummond-Arthabaska riding in 1867, but was defeated in his re-election bid in 1871 by Wilfrid Laurier of the Liberal party.