The Inner Temple in London will host the show on 11-13 September, which the RHS expects will attract 15,000 visitors.
In an experimental move, marquees filled with plant exhibitors will be open and face the outside of the Inner Temple garden so visitors can see the garden better.
One-third of the tickets have been sold. The show, which may become annual, replaces the RHS Autumn Show. Sweet described it as "not Chelsea in miniature but with a different feel ... an English tea-on-the-lawn atmosphere".
The show is part of a celebration of 400 years of the Temple. The RHS ran Chelsea's precursor show at the Inner Temple from 1866-1911.
Freshfields Bruckhaus Deringer is sponsor. Head gardener is Andrea Brunsendorf. Exhibitors include: John Woods, HW Hyde, Old Court Nurseries, Tynings, Winchester Growers, Botanic Nursery, Pennard, Hoyland and Raymond Evison.
- See www.rhs.org.uk/innertemple.