The Sydney family of three visited Floriade's opening weekend and said four-year-old Matilda was ''in heaven'' among the flower displays at the largest spring festival in the southern hemisphere.

''It was beautiful,'' Mrs Askew said.

''I like that there's so many different things to do.

''There's the beautiful flowers, but also the carnival type of stuff, too - the rides, the animals, the fairy floss.

''She enjoyed it a lot.''

Canberra's 26th Floriade had a slow start because of unpredictable and rainy weather on Saturday.

But sunshine got the crowds to turn up on Sunday, a welcome boost for organisers who are hoping numbers this year will again exceed 400,000.

Last year, the month-long festival attracted 442,000 visitors.

Floriade spokeswoman Adelina La Vita estimated numbers were in ''the thousands'' over the launch weekend.

After a dreary start on Saturday, ''the park was very full of people'', Ms La Vita said. ''In all of the marquees in the inspiration hub, there were lots of people watching the demonstrations.

''When I went to check in on [the cooking demonstrations by] Julie Goodwin, all of the seats were taken and it was standing room only.''

Monday is the start of the festival's smart living week.

Gardening Australia host Costa Georgiadis will return and The Cook and the Chef's Simon Bryant will also appear later during the week.

''It's all about sustainable living, living smart and watching your footprint,'' Ms La Vita said.

''Demonstrations are focused on ecological living … looking at all of the smart ways we can live in the spaces we own.''