You take your chances with outdoor theatre, and it isn't far into this alfresco adaptation of Frances Hodgson Burnett's novel that umbrellas begin sprouting round the arena. But there's nothing wrong with the British climate for once: brightly coloured brollies are an integral part of Jessica Curtis's design, which is an ingenious means of summoning a garden from nowhere, even if fast-growing fungi seem to have been substituted for the tall, untended grasses described in the book.

The infrastructure of Grosvenor Park theatre becomes more impressive by the year. What began as a few raked seats around a flowerbed has evolved into a fully enclosed amphitheatre that echoes Chester's Roman foundations, and Kate Saxon's production proves to be a delightful way to fill it. Burnett's novel can feel a bit preachy (it was, after all, a fictional treatise on the principles of Christian Science), but Jessica Swale's adaptation does not shy away from the procreative theme, with a full and frank discussion revealing that what separates boys from girls is their "dangly bits".

The redemptive aspect of the tale is very well told. Starved of light and restrained in callipers, young Colin Craven believes he will always be an invalid until exposure to the garden enables him to see, walk unaided and take up the accordion (the last does not strictly occur in the novel, but like the rest of the cast, Max Gallagher is an accomplished musician). Jessica Clark transforms the mealy-mouthed Mary Lennox into a more engaging character than she appears in the book, and Gary Mitchinson gives a convincing impression of Dickon's ability to communicate with animals. Then again, he hardly needs to bring any charm, as Toby Olié's characterful puppets are charming enough in their own right.

• Until 24 August. Box office: 0845 241 7868. Venue: Grosvernor Park Open Air Theatre, Chester.