He said he is working for the industry on the control of invasive non-native species under the Infrastructure Bill, which he said could "demonise" plants such as Rhododendron ponticum, cotoneaster, crocosmia and Ailanthus altissima (tree of heaven).
"We don't want to see blanket sales bans on these plants people see as invasive," he said, adding that the term "invasive" needs more explaining. Curtis Machin questioned the inclusion of R. ponticum because it is used as rootstock and is "not invasive on nurseries".
Non-Government organisations are pushing for more plants to be added to the list as well as sales bans, but the HTA advocates a voluntary code of practice to educate gardeners, he explained. "We don't want the demonisation of plants."
He also spoke about narcissus sales in supermarkets, where the Health Protection Agency has said daffodil bulbs and cut daffodils should be displayed away from fruit and vegetables in case of the poisonous plants being mistaken for chives, cooked and eaten - 27 cases were recorded in 2014.
The HTA has linked with the British Retail Consortium to talk about labelling and display rules.