Garden centre owner Richard Calder said he hopes the rebuild will cover the original shop footprint and will also include a higher roof to let in more light.
He added: "We want to enhance what we've got. We want a bigger coffee shop, a better laid-out furniture and barbecue section, more storage and a staff room."
Pleydell Smithyman is working up plans for completion and submission in 2010. The Shropshire-based architect worked on Daisy Nook's three-span curved roof building three years ago.
The centre turns over £2m a year and employs 38 staff.
More than 200 International Garden Centre Association delegates visited Daisy Nook this week before moving on to Blue Diamond Trentham. Later visits will include Hayes, Chatsworth, Barton Grange and Woodford Park garden centres.