The "Polo" or "doughnut" concept is Roper's own, and features a circular area to sell products surrounding a central planteria, which is visible from every part of the garden centre.
Le Friquet is also the head office of the 11-centre Blue Diamond group, which grew out of the 100-year-old Guernsey Fruit Export Company and expanded into garden centres under Mike Vaudin, until he retired in 2006.
Roper, who has almost 20 years' experience as a garden retailer, took over from Vaudin in 2006. He expanded the group by buying Hazelfields in 2007 and Derby and Matlock garden centres in 2008, taking on management of Chatsworth garden centre at the same time.
Le Friquet, which replaces a plant centre on the site and a pet and garden centre owned by Blue Diamond on the island, innovates from the outset. Seasonal bulbs cover the entrance and exit. Roper says: "Customers are not adjusted when they come in so (the displays) are also by the way out, which means they are hit twice."
The planteria covers the 6,500sq m interior and has a huge octagonal sail from Fabric Architecture at the centre. Blue-sky thinking continues with houseplants sourced and managed by Floreac. Roper says this has boosted this difficult area and he now sells plants ranging from £6.99 to £160. "We're not giving up on houseplants," he insists.
Roper's other centres are big on gifts and indoor living, and last year trialled his aspirational gardening boutique area. The section features classic designs in pottery, iron and lead from the Continent. "We want a more classic, neutral look," he explains.
The centre features cut flowers ("we don't want supermarket flowers") in a cool room. Around £1,300 of stock has to be sold each week. Next up on the circular walk are the promotions - at the moment it's two foliage plants for £10.
"Living with natural light in the garden" follows, not from Solus or Gardman promos but using candlelight instead. Roper was at Glee but also particularly rates European shows Maison & Objet and Ambiente for indoor-living suppliers.
The centre's layout means space is limited for furniture, so it is "far more" plant-based than other Blue Diamond centres such as Trentham. The clutter-free style feels spacious, while attention has been given to fascias, slat walls, information points and plinths.
Blue Diamond took 10 years to get planning permission for the centre and building began 15 months ago. Builder Hodges and structural engineer Newspan built the structure according to Roper's design.
He says costs are 50 per cent higher on the island but still expects a turnover of £6m-plus after spending £6m-plus on the centre, though the building cost £200/sq m - less than the industry average of £300/sq m. Roper says: "We did £3.5m before out of a shed."
He hopes one-fifth of that revenue will come from the "classic, not contemporary" restaurants, on which Roper "pushed the boat out" because he says the island has a lack of places for daytime eating.
Roper's philosophy is: "Retail is about creativity - my inspiration is from life experience, such as staying at five-star hotels - that's where ideas germinate.
"I've had 18 years in the industry. I started on a shoestring. The budget is bigger these days, but it's still about choosing the right tile. The ambience sums it up. Feel-good, loyalty and product merchandising wraps around that."
Roper says garden centres that give out loyalty cards are "desperate to cling on to customers" and prefers John Lewis, Waitrose and Selfridges as influences to other garden retailers.
Le Friquet also features a soft play area for children, a terrace panorama pizza restaurant, wood floors, a lecture theatre and a pet section potentially worth £750,000 a year.
Roper sums up his approach: "Garden centres have the most challenging job in retail; it's hardest to get right because of the sheer diversity of products."
1991-1999: Develops, then sells, Waterside Garden Centre in the
1999: Joins Blue Diamond
2002: Becomes director of Blue Diamond
2006: Replaces Mike Vaudin as managing director of Blue Diamond
2007: Buys Hazelfields garden centre
2008: Takes over three Garden Centre of Excellence sites
2009: Opens flagship Le Friquet site and works on plan for similar site