The £1.8m Canterbury Garden Centre project includes a 1,500sq m indoor area with coffee shop and areas for furniture, gifts and clothes. An outdoor area covers 1,000 sq m.
Director Edward Boult said: "The opening followed a supreme effort from the contractors and staff led by manager Peter Cassell.
"We laid the base course of Tarmac on the car park on Thursday," said Boult. "On Good Friday we plumbed in a toilet and sink, and we were opened by 10.30am."
The wet autumn and drainage problems caused delays, but the centre, with eight full-time staff, was completed in only seven months, said Edward Boult.
More than 1,000 people visited the garden centre on its first weekend despite the business setting aside no money for advertising the opening.
Grovewell Garden Centres' other Kent retail base, in Tenterden, has 10 staff and turns over £2m a year.