The restaurant at the Richmond, London nursery opened in 2004 and won the inaugural Garden Retail best catering award in 2007.
Chef Skye Gyngell said:
"Last year was the first time we broke even. We still have dirt floors, a mishmash of glasses, the tables are wobbly and the service is pretty haphazard at times, so I was not expecting a Michelin star. I always pretended I didn't care but I do now — it's fantastic.
"We serve as simple food as possible and try not to interfere with the flavours too much. To be rewarded for all our hard work is absolutely amazing."