Almost 100,000 tree orders bound for Northern Ireland have been cancelled as a result of trade difficulties caused by the Irish Sea border.
Buyers including the Woodland Trust and Belfast City Council have faced issues with orders due to problems importing the trees from Great Britain to Northern Ireland.
Under the Northern Ireland Protocol, agreed as part of the UK and EU's Brexit deal, the region remains aligned with the EU on trade rules.
The Guardian has reported this causes difficulties for those wanting to import trees into Northern Ireland from GB.
Problems include roots of plants and trees having soil on them due to concerns around pests and disease, the EU’s list of species prohibited or restricted for import from third countries which includes certain trees, and concerns around paperwork, customs charges and health certificates making the process more difficult.
Scottish company Alba Trees said it had been forced to turn down an order for 70,000 oak trees "because we can't ship them".
Chief Executive Craig Turner said the company usually sells around 250,000 trees to Northern Ireland every year.
“At a stroke Brexit has taken away a huge chunk of our business," he said.
The Woodland Trust has cancelled an order for 22,000 trees which were due to be used as part of their greening project for schools and communities, while Belfast City Council has confirmed an order of 300 large specimen trees from England has been "delayed due to new rules around the movement of plants".
Maelor Forest Nurseries in Wales said it was about to cancel an order from Northern Ireland for 1,000 oak trees and had decided to stop selling to the region.
The Woodland Trust's Estate and Outreach Manager Gregor Fulton said the situation was "a disaster".
"They’re just stopping any exports from mainland UK over to Northern Ireland. We can’t get any trees over from any of the nurseries that we would usually deal with over there,” he told the Guardian.
“We thought it would be teething problems that would be resolved quickly. It just seems ludicrous really,”
"The irony is that I can now get a tree easier from Latvia than I can from Britain, which totally undermines all the work on biosecurity".
UUP MLA Rosemary Barton said the protocol had robbed schools of the opportunity to take part in the Woodland Trust's greening project.
"Once again we are seeing how iniquitous and ridiculous this NI Protocol is, both to the horticultural industry and the economy of Great Britain and Northern Ireland," the Fermanagh and South Tyrone MLA said.
“With these same regulations applying to garden plants and seedlings many young people will be denied the pleasure of escaping from the school classroom or home schooling to sow seeds, plant up seedlings in their window boxes or plant some vegetables all because the seedlings were propagated using British Soil. It's ridiculous.”
It emerged last month that some garden centres in Northern Ireland were also struggling to get plants from GB due to the new trade rules.
A number of centres have reported regular supplies cancelling their orders due to concerns and problems associated with the Irish Sea border.