There are concerns in the industry that garden centres may find customers returning dead plants with frozen roots that they sold as healthy with hardiness guarantees this spring.
Some staff may not have experienced the problems caused by the worst freeze for 20 years. Containerised plants such as laurel, magnolia, camellia and Italian stock could be impacted by frozen roots.
Plant guarantees may be called into question, while garden centres may be unable to return damaged plants to suppliers.
Adlam said: "The trouble with evergreens is that they don't tell you when they've died. Centres will be legitimately selling some plants this spring and it will not be until April/May when they start browning off because they didn't realise the roots were non-active.
"There is the potential that garden centres will be selling plants that look healthy but won't be able to supply themselves with sufficient water once growth starts in March/April/May. Customers will take plants back to garden centres under plant return guarantees."
Adlam said there was little legal basis for garden centres to return frost-damaged stock to suppliers and distributors.
Glendoick Garden Centre managing director Ken Cox said: "People who work in planterias may not have seen this before. Lots of centres are giving five-year plant guarantees. We may see 'no returns' signs being put up. Centres may try and return to suppliers but they will say: 'It's not my fault.'"
HTA business development director Tim Briercliffe said: "These are exceptional conditions. If HTA member garden centres or nurseries are unsure what to do, they should ring John Adlam on our nursery stock advice line - 01379 741999."
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