More than 35,000 people have signed up to the NFU's food security campaign as supermarket shelves lie empty of fresh fruit and vegetables.
The campaign seeks to galvanise public support behind the idea that supermarket shelves should never be empty of any food that can be produced by UK farmers.
It follows the UK's largest retailers imposing national purchasing restrictions on fruit and vegetables due to extreme weather hitting harvests abroad, as well as high energy prices.
Asda, Morrisons, Aldi and Tesco have placed purchasing limits on items such as tomatoes, peppers and cucumbers.
More than 35,000 members of the public have signed the NFU's online petition, which calls on the government to commit to 'simple steps' to bolster British food security.
The NFU said the government must have a plan to secure British food supply "now and into the future".
The union said recent events had shown the vulnerability of the UK's supply chains, in turn putting pressure on domestic food production.
The cost of energy, animal feed and tools to grow food today are at historic highs, with inflation in agriculture remaining at nearly 19%.
According to the NFU, there are already 7,000 less farming businesses in the UK today compared to before the Covid pandemic.
"More than 35,000 members of the public have joined our food security campaign as supermarket shelves lay empty of salad items," the NFU said.
"We have an opportunity to send a clear message to the UK government: the public care about the food they eat and the farms who produce that food.
"Show your support by signing the Back British Farming campaign for food security."
It comes after NFU President Minette Batters told the union's annual conference “the clock is ticking” and that “time is almost up for this government to start walking the talk”.
"It’s ticking for those farmers and growers facing costs of production higher than the returns they get for their produce," she said.
"It’s ticking for the country, as inflation remains stubbornly high, and the affordability and availability of food come under strain. It’s ticking for our planet, as climate change necessitates urgent, concerted action to reduce emissions and protect our environment.
"And it’s ticking for government – to start putting meaningful, tangible and effective meat on the bones of the commitments it has made."