The pop-up will be housed at a special dining room in the Ranelagh Gardens, and will offer a bespoke menu inspired by gardening.
For £60 per head guests can expect traditional finger sandwiches, scones and a selection of tea, along with a selection of unusual treats created by The Dorchester’s head pastry chef, David Girard and designer florist Philip Hammond.
These include the Garden Basket - a chocolate cake decorated with edible flowers and chocolate ladybird, while the Premise of a Gardener combines lime, white chocolate and strawberries in a flower pot.
In honour of the late author Ronald Dahl’s 100th birthday, diners can also enjoy 'The Dorchester And The Giant Peach' – a peach mousse served with verbena flowers on a crispy rice biscuit.
With live music from a resident pianist, the room will also be decorated with English-grown floral displays of peonies, roses and hydrangeas.
The afternoon tea will be served at half-hour slots from 3.30-5pm, where each guest will receive a complimentary glass of Laurent-Perrier champagne.
Laurent-Perrier is also hosting an all-day champagne lounge at the Chelsea Flower Show, which will be stocked with champagne and snack foods.
Nick Mattingley, RHS head of shows, said: "We’re always seeking new ways to enrich the visitor
experience at our flower shows so we are delighted that on top of all the other culinary delights on
offer, The Dorchester will be serving its iconic afternoon tea at the RHS Chelsea Flower Show 2016."
Earlier this year, electronics brand LG announced it would create a garden at the Chelsea Flower Show to showcase its technology offering.