The 23-year-old music star - who is playing at the world famous festival in Somerset, South West England tomorrow (25.06.10) -
has something extra-special planned for her band's performance but is keeping it under wraps.
She told BANG Showbiz: "Obviously I've got a big surprise at Glastonbury but I don't want to tell you any more because I want it to be a surprise."
However, those who aren't lucky enough to be attending the festival - which will see Gorillaz, Muse and Stevie Wonder headline - could be set to see more "exciting" things from the redhead singer later in the summer.
Speaking at the Reebok ViceStyle.com launch party, in London, she said: "We've got lots of exciting stage stuff coming up in the summer and we're always working on new material."
Florence is not the only artist who has a Glastonbury surprise in the making. Headliners Muse have also promised a "very, very special surprise guest".
Drummer Dominic Howard revealed: "If it comes off, it'll be a huge moment for Glastonbury. It will take it to a whole new level for us."