The central London street, which has lain largely idle since being fenced off to the public in 1982, fronts both Number 10, the Prime Minister's residence, and Number 11, home of the Chancellor of the Exchequer.
The move follows on from the success of the vegetable patch in the Number 10 garden, which is managed by Royal Parks. But there are concerns that the plot may fall into the same neglect witnessed at the National Trust's flagship allotment in nearby Queen Anne's Gate, once the novelty as passed.
But 10 Downing Street representative Flora Lipo brushed off the suggestion, saying: "This will be a vital resource for government food procurement. The Prime Minister and the Chancellor have both pledged to get digging, with Gordon Brown particularly eager to try his hand at turnips."