Video report by ITV News Correspondent John Ray
He is the fourth generation of his family to run this award-winning business, but Robin Mercer has never known a future quite so uncertain.
"It’s ridiculous. Everything you see here is now illegal to import."
This is the Hillmount Garden Centre, just outside Belfast, and Robin surveys the empty wooden tables that should soon be groaning under the weight of spring plants.
St Patrick’s Day is the start of his big sales period.
The problem; he can no longer deal from mainland suppliers. At issue; the soil the plants stand in and rules designed to protect the bio-security of the European Union (EU).
"From now on, anything with bark, or wood chip, or soil is banned from coming into Northern Ireland from Britain," says Robin.
"Every day we hear of new rules and regulations. And some are just atrocious."
"Really speaking, it’s backfired on us," says Robin, of a deal which promised Northern Ireland, uniquely, the best of both worlds – access to both EU and UK markets.
Instead, the Northern Ireland protocol – designed to maintain an open border between the Republic and Ulster that underpins the good Friday agreement - has imposed unforeseen custom checks and prohibitions on goods coming across the Irish Sea.
"I never thought we’d be so abandoned," Richard Fry tells me of his difficulty restocking his farm shop at Templepatrick.
Ulster said No to Brexit; though a majority of Unionists embraced it in the belief it would herald a return to sovereignty.
Now, the talk in unionist communities is of betrayal. Whoever they blame – and mostly it's Boris Johnson and the EU rather than their own local leaders – it has amplified insecurities.
Amid the loyalist murals of east Belfast we meet the Rev Mervyn Gibson, grand secretary of the Orange Lodge. He says he fears reunification with the South by stealth.
"We were told there would be no border down the Irish sea and sadly there is now a border there.
"People will look to the Republic and our economic re-orientation will be in that direct and that will feed into those who sadly want a united Ireland."
Ulster’s nationalists and Republicans say Brexit is a mess of unionist making and that the ominous graffiti which has appeared, threatening customs staff, is an attempt to whip up hysteria to distract from the empty shop shelves left by missing British goods last month.
It’s ironic as these were the Brexiteer champions’, Deputy First Minister Michelle O’Neill said last week.
Unless the protocol is unpicked, Robin Mercer worries how his business will survive into a fifth generation. But the forces unleashed go far beyond the flower beds.
This year, unionists plan to celebrate Ulster’s 100th anniversary. But they’re feeling less confident of their position within the United Kingdom.
Adrian Guelke, of Queen’s University, and a long time observer of Northern Ireland’s politics, puts it succinctly - "The siege mentality is back."