B&Q from 6.30am, as an extension of their Let's Get Gardening campaign.
The event is in partnership with the Capital Growth campaign, and is supported by London mayor Boris Johnson, who said of the venture: "London has embraced the 'grow your own' revival as testified by the army of 35,000 volunteers involved in our Capital Growth scheme. This green fingered bunch is helping to beautify our city and bind communities together in a shared passion. I hope this tomato plant giveaway will entice a new crop of Londoners to get the gardening bug, put on some wellies and join up to Capital Growth."
Hidden within one of the tomato plants to be given away will be a ticket to the Chelsea Flower Show - an additional incentive for commuters to pick up a plant on their way to work this Friday.