The fire at the garden centre in Rochdale, Lancashire, hit the pets, aquatics and houseplants area.
A representative said: "We've managed to get some power going so the tills are up. It's the bottom end of the centre that is damaged."
Fire engines from Rochdale and Chadderton attended the scene.
The fire threatened to destroy the whole of the centre but fire crews brought it under control, confining the damage to around one-third of the single-storey building.
Investigators are working to establish the cause of the blaze.
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