BALI and the HTA said they would protest to the Home Builders' Federation and Taylor Wimpey after the latter wrote to its subcontractors.
BALI technical director Neil Huck said: "We, too, will write: five per cent is a big margin to swallow and most landscape firms may find it hard to survive such a hit." He met colleagues last week and they will regroup again in a fortnight. Huck added that it was too soon to comment further.
HTA business development director Tim Briercliffe said: "This is a very short-sighted response to an immediate problem and we will also write to the company.
"It is particularly worrying as homes are supposed to be more environmentally friendly, and these actions suggest less landscape: you can't build half a roof, but you can lop planned landscape work in half."
The Home Builders' Federation refused to comment, but the letter from Taylor Wimpey insisted the firm had to take "urgent action to manage down our cost base". Subcontractors, it said, must "play their part".
Palmstead Nurseries sales and marketing manager Nick Coslett said several of his landscape-contractor customers had received the letter from Taylor Wimpey. "It's bad news for the industry: nurseries supplying into this sector are still getting the same prices as they did seven to 10 years ago.
"Then to squash subcontractors by five per cent on existing contracts is arrogant behaviour, just like that of the supermarkets. It's not illegal, but morally it does not foster trust in the business. Negotiation is better. Landscape contractors don't have the margins to absorb this size of cut and could be pushed to the wall. And while they could be replaced by other small contractors, they, too, would face the same hardships."
Horticultural consultant John Adlam warned the industry could be ruined by squeezing contractors. "Growers aren't making the money to invest enough in new systems and technology. If you continue to reduce what you pay them, we will have an outdated and inefficient industry that has no sustainability."