The union's pledge follows meetings with the main supermarkets, during which the NFU explained growers' concerns about the future sustainability of the horticulture industry overall - and specifically the field vegetable and protected crops sectors.
Although retailers expressed their support for British horticulture at the NFU's meetings, they also referred to the extreme competition in the market and would make no promises to growers.
The NFU is now targeting other parts of the supply chain to help tackle the problem.
NFU horticultural adviser Chris Hartfield said: "The NFU will ... remain in contact with retailers on how this issue develops.
"Following discussion with the Board for Horticulture we will also be contacting the intermediaries in the supply chain, principally those acting as private marketing agents, to ascertain their reaction and response to the current difficulties in the industry.
"In the short term, there is no escaping the reality that increased returns for growers from the supply chain are necessary if the industry is to be able to respond to the threat of increased costs and particularly re-invest in the business."
The NFU's campaign began in March this year, when it wrote to the major multiples as growers were hit by substantial increases in costs of energy, labour, fertilisers and land rents.
The letter read: "Our field vegetable and (protected crops) growers are telling us that these price increases have not reached them, leading to our concerns that we are fast approaching a tipping point, when growers who have the choice will no longer grow vegetables. In our view this would be a travesty."
Since March, new figures from the British Retail Consortium have shown that fresh produce retail prices inflated by 10.8 per cent in the 12 months to July.
Overall inflation for July was 4.4 per cent - the highest since the early 1990s - although Processed Vegetable Growers' Association chief executive Martin Riggall told Grower that these price increases have yet to relate to the amount growers are getting paid.
He said: "There have been some increases on some of the contract crops but (on the whole) the increases at the grower levels have been nothing like the retail level in percentage terms. However, I think we are going to see a bit more of an increase in next year's contracts because input costs have gone up so dramatically."