Peter Tinsley Landscaping, which has scooped the event's best-in-show Brockhouse Trophy for the past two years, will be returning this year.
Last year, the firm's Japanese Garden, including a Westmoreland slate rockery and waterfalls, was inspired by the Japanese garden in Calderstones Park, Liverpool.
Other top gardening experts at the show, which takes the 1920s as the theme this year to mark the anniversary, will include Sir Roddy Llewellyn as well as show patron David Bellamy.
Another show patron, Diarmuid Gavin, said: "It's my very favourite flower show - exciting but utterly unpretentious. It's colourful, loud and cheery."
Also on show will be the National Society of Allotment & Leisure Gardeners and a floral marquee, co-ordinated for the past 37 years by Josephine Yates.
Talks will include presentations from Michele Martin of the North West Society of Garden Designers on allotments and gardening for people with disabilities.
The Southport Flower Show, which takes place at Victoria Park in Merseyside, attracts crowds of up to 80,000.