Members of the Soil Association used the seminar on organic standards to suggest that growers should avoid being too prescriptive in their rotation regimes.
Policy director Peter Melchett said: "In this economy you need to grow something that is productive and economic and people want to buy. If you are too prescriptive it can hamper your business viability."
The Soil Association launched its consultation because its current standards for glasshouses and polytunnels "were probably a bit ad hoc and we want to get our ideas in order to encourage sensible new EU regulations," said Melchett.
Organic Growers Alliance chair Alan Schofield said: "When it comes to prescription verses flexibility in harsh economic times, I need freedom to choose varieties, inputs and situations that work for me.
"If I make a loss through a decision I've made, that's my fault. But if I make a loss because of a decision the Soil Association has made, I want to take someone to task."
Adrian Izzard, who runs Wild Country Organics, said: "You can have best practice but not fixed rules otherwise you can lose thousands on plants by having to pull up everything to stick to a rigid rotational plan. This can put businesses out of operation."
Peter Dollimore, a grower at Hankham Organics, asked: "What is best practice? Some people don't use rotation in a glasshouse and achieve good results, while others rotate lots of crops but fail to grow good-quality vegetables."