The Dahlia enthusiast won 36 consecutive gold medals between 1961 and 1999 at RHS shows, winning the Williams Memorial Medal in 1977 and 1994. He was an RHS shows and Dahlia committee member.
He developed Aylett's Nursery from 1955, having trained at Oaklands College, where he later became a governor.
Aylett celebrated his 50th year as managing director by publishing his autobiography, 50 Golden Gardening Years, in 2005.
His son-in-law Adam Wigglesworth is now a director of the £6.8m-turnover garden centre and nursery and sits on the HTA retail management committee.
Aylett is survived by his wife, Hazel, and two daughters. A service of thanksgiving was due to be held in St Albans Abbey on 2 June.