A grower, who did not want to be named, said: "The supermarkets [and chains like B&Q] have a huge commercial dominance. They can impose any deal they want and the only option we have is to walk. That is not necessarily in their best long-term interest but it has always worked in the past for them. They have so many advantages.
"I can't see how legislation will help but if we all published the terms we have with each supermarket and made them freely available, the general public will get an idea of how uneven things are.
"That could redress the balance. The supermarkets place great store on their good name in the marketplace and the terms have to be (counted) against their good name. If it was more widely known that we are paid in 90 days when customers pay on demand, it may force them into giving us better terms."
Meanwhile, B&Q has asked a market research company to survey suppliers on their attitude to the company. The NFU has asked for copies of the replies from growers.
The grower said: "They sent out a survey via a market research company. There have been some hard-hitting comments and negative answers, I believe."
Growers have signed up for slower payment for 2009 but some suggest they will not sign for 2010.
B&Q is attempting to build bridges with growers, who say the chain's horticulture buyers are difficult to contact.
The grower added: "Two weeks after we signed we got an invitation to see B&Q, saying B&Q was concerned and would do things better next year, with its Vendor Buyer Agreement (VBA) covering credit terms, rebates and distribution. But the meeting was cancelled and we've not heard from them since.
"The hardy-stock buyer is hard to contact. One nursery tried to go up the chain to confirm a range but then lost all their business. There has to be trust in a trading relationship but that no longer applies between B&Q and suppliers.
"In the past few years growers have failed to reach their reserves, with some 30 to 40 per cent down last year. But if the weather was poor and there were no customers what else can you do? People aren't blaming B&Q for poor sales. This year has been better.
"Most suppliers are over their reserves and that goes a long way towards reducing the balance but they have changed terms to 90 days on the back of that, which has strained the already very poor relations between B&Q horticulture buyers and suppliers."
A B&Q representative said: "We can confirm that we have carried out a satisfaction survey with all our suppliers recently, including our horticultural suppliers. This survey is in line with our objectives to develop closer partnerships with all our suppliers.
"We treat all our suppliers on an individual basis dependent on their commercial position. Feedback from the survey and individual supplier negotiations are confidential and commercially sensitive."
Subscribe to Horticulture Week for more news, more in-depth features and more technical and market info.