But Millbrook garden centres, in Crowborough and Gravesend, very much belong to the Allen family.
Allen and her late husband Dick Allen built Crowborough in East Sussex 30 years ago and then Millbrook in Southfleet, near Gravesend in Kent, 15 years ago.
Daughter Tammy (now Woodhouse) was five when the first centre opened and 15 when the second was developed. Tammy, who came into the business in her early 20s to help her mother when her father died, is now taking over as managing director as Sue retires.
The Gravesend centre played host to a retirement/30th anniversary party recently, with 130 industry figures such as Scotts' John Ashley and Coolings' Paul Cooling invited.
Allen adds: "We've been working towards this succession for five years. We've been grown up about it. For the past 18 months I've been doing less and less so it's not going to be a horrible shock to me or Tammy."
Former GCA chairman Allen says she will work on the shop floor sometimes because that is what she enjoys. She will also continue to work as president of the International Garden Centres Association, which has 19 member countries and will hold its congress in Japan in 2010.
The Millbrook team is always involved in the wider garden centre industry - events, awards and regional groups.
Millbrook Garden Company has won planning permission for a 2,356sq m redevelopment of its Gravesend centre. Allen says: "Our policy of continuous improvement extends to many other areas of the business.
"Plants are very much the core of our business, with much of our stock coming from our own production nursery. As a company we believe in supporting the industry on a national basis and are actively involved with both the HTA and GCA.
"I've got great friends in the industry through trade body membership. I was GCA chairman and my husband was president of the HTA. I've always believed with any of these organisations you get out what you put in. That's been proved over and over again."
Horticultural Trades Association The Horticultural Trades Association (HTA) is the trade association for the UK garden industry. It is dedicated to helping develop the industry and its member businesses, which include most garden centres and other garden retailers, growers, landscapers, manufacturers and service providers.