The city centre urban gardening festival, focused in St Anne's Square and King Street on 2-10 August, is run by the Heart of Manchester Business Improvement District under this year's theme: "Grow Your Own."
BBC Gardeners' World presenter Rachel de Thame, the National Trust's first urban gardener Sean Harkin and an as yet unnamed "celebrity gardener" will be judging the show gardens.
Harkin said: "Dig the City is quite exciting for us. It's family orientated. Novice gardeners, new designers and groups can all get involved. It's a really good way to test the water and get sponsorship for future shows. We're looking at how inventive people can be - it doesn't have to be haute couture."
He added: "I love the RHS Chelsea Flower Show but it's unbelievably high end, like a catwalk. It's the dream but the reality of most people's gardens is they'll never look like a Chelsea show garden. That's fine - normal gardens are there to be lived in."
The festival hopes to improve Manchester long term. Last year, a temporary forest of 75 trees was installed in Exchange Square and they have been planted permanently in a new housing development.
The deadline to register for show garden entries is 18 April, although this may be extended.