Osborne told the BBC the "economy can now afford" to raise the rate, currently £6.31 an hour, for over-21s and said he supports an above-inflation increase.
HTA Head of horticulture Raoul Curtis-Machin welcomed the move, saying it is "a general indicator of economic recovery".
He added: "Horticulture remains a fairly low-paid industry. We would like to see a slow, steady rise in horticulture incomes across the board, including all sectors."
Welcoming the move, Association of Professional Landscapers chair Mark Gregory said: "I'm all for getting away from a minimum wage. The industry is gifting its services too cheap."
But ISS Facility Services Landscaping managing director Phil Jones said a rise could cost jobs. For existing contracts, ISS will have to "take the hit" because local authority clients will be neither willing nor able to pay more, he pointed out.
But unless local authorities pass on the cost to council taxpayers, on new contracts clients will expect more efficiency savings and contractors will have to employ fewer people, said Jones.
Garden Centre Association chief executive Iain Wylie said: "It may impact numbers centres can afford to employ. They have to work out part-time versus full-time staff."
The Low Pay Commission will make its recommendation on any increase to the Government next month.