But through a combination of sweat, skill and good fortune, the Kerley family has established itself in the plant-breeding landscape, turning improbabilities into profits on a regular basis.
Petunia Priscilla turns 15 this year, and unlike many breeding "breakthroughs", the world's first double Petunia with a hanging habit is still a bestseller as it enters adolescence.
The story of its origins is legendary, as Kerley explains: "In 1995, my wife crossed a Surfinia with a double Petunia seedling. She used two flowers, so she made the pollination twice. She raised 100 seedlings and one of them was Priscilla - it was the only one in that cross that was any good.
"It's an amazing fact, except there's another way of looking at it. When we bred Priscilla, we didn't have a model in mind. After that we had a model, and once you do that, it's much more difficult to match the model.
"What really set Priscilla on its feet was that it was a good growers' plant, and I came from the amateur sector, so I asked what growers wanted and that became the model."
It did not take long for the world to take note, as Kerley offered it to Unwins, where he worked as a director, and it sold more than 105,000 plants in its first year. It was soon picked up around the world and became a key product for the likes of Ball Colegrave, one of Kerley's biggest customers.
After the plant's introduction in 1997, Kerley stayed on at Unwins, where he had been for more than 25 years, but soon the workload became unrealistic.
"In 1998 we had a fledgling business with Priscilla and I was still trying to work 60 to 70 hours a week as a director of Unwins. At 11 o'clock every night we were still working in the greenhouse by lamplight. My wife asked me, 'What are we going to do next year?'. So that's why we started the business."
Over the past 11 years the company has grown, introducing 62 petunias and taking on Kerley's son Tim. And there have been plenty more breakthroughs, too, not least the recent announcement of the new Balconita Pansy series, the world's first truly trailing pansy propagated from vegetative cuttings.
All are bred with the grower in mind, focusing on early flowering, good branching and appearance on the bench.
"We first make sure it works for the grower, then we test it outside," Kerley explains. "That's different from most UK breeders, who would start by finding a good garden plant and then try to make it work for growers."
It is a laborious process as 18,000 Petunia seedlings, become 500 hanging baskets, which become 250 varieties.These are made into mother plants, raised from cuttings the following spring and tested in pots and baskets, which become 80 trialled outside.
It takes 12 months to go from 18,000 to 80, from which just five or six are introduced each year.
Although Priscilla took just two years to come to market, the model Kerley aspires to means most introductions take at least five years, with some taking far longer - Balconita pansy has been in development for the past 11 years.
But it is a model that works - two-thirds of sales are now from exports, despite Kerley's decision not to breed for specific markets.
With overseas sales come new challenges. Kerley says a key problem is variety rights. "What some growers don't realise - and I'm talking around the world - is that if they don't pay variety rights it's hurting them in the long term, because they are not paying the research funding that will bring them better varieties in the future. That's the reason we are a member of Fleuroselect, because it is such an important issue."
Another key issue facing all breeders is plant patenting and how current legislation is interpreted for horticulture.
Utility patents top Kerley's list of concerns: "I'm very troubled by what utility patents are being used for. I can't understand that someone can go to a wild species, find a gene that would be useful in a tomato, for example, and then cross it by normal breeding and put a patent on that. I feel that is stifling innovation because history says a lot of varieties would never have been made.
"If Surfinia had a utility patent it wouldn't have been a spur to Suntory's breeding. I think it's a spur to a breeder knowing that someone else is going to try and improve your variety. So I don't think it's right to put a big exclusion zone around a variety - it stifles innovation."
Though there may be challenges on the horizon, Kerley looks set to meet them head on, and his message for growers is to look for the product that "in five years' time is going to be 20 per cent of their sales".
That may seem a long way off for most growers, but Kerley probably already knows what it is, and has them hidden away on his trial grounds.
1969-70: Unwins Seeds
1970-73: HND in Commercial Horticulture, work experience at Thomas Rochford Sluis & Groot (now Syngenta)
1973-99: Unwins flower seeds manager, office manager, assistant to managing director, technical director, commercial director
1983-99: Managing director of SE Marshall & Co, Unwins mail-order subsidiary
1999-present: Owner and manager DW & PG Kerley
Breeding achievements include: Antirrhinum Attraction series dwarf bicolors, Lobelia Ruby Cascade (first true red), several sweet peas, Spinach beet Popeye, tumbellina Petunia series, Designer Petunia series, Fanfare Petunia series, Future Petunia series, Belarina Primula series, Cape Fuchsia series, Balconita pansy series.