Asda and Morrisons are putting limits on purchases of some fruit and vegetables as supermarkets face shortages of fresh produce.
Asda is capping sales of items such as tomatoes, peppers and lettuce at three each per customer.
Morrisons said limits of two items on products like cucumbers would be introduced at stores.
However, Tesco, Sainsbury's, Lidl, Aldi, Waitrose and Marks & Spencer currently do not have limits in place.
Pictures of empty supermarket shelves have been circulating on social media, after shoppers found it hard to get some items in recent days.
The shortages - which are affecting Ireland too - are largely the result of extreme weather in Spain and north Africa, where floods, snow and hail have affected harvests. At this time of year, a significant proportion of what the UK consumes usually comes from those regions.
Shortages could last a few weeks
The shortages are expected to last "a few weeks" until the UK growing season begins and retailers find alternative sources of supply, said the British Retail Consortium (BRC).
Andrew Opie, director of food and sustainability at the trade group, added that supermarkets are "adept at managing supply-chain issues" and were working with farmers to ensure the continued supply of fresh produce.
In the winter months the UK imports around 95% of its tomatoes and 90% of its lettuces, most of it from Spain and north Africa, according to the BRC.
Minette Batters, president of the National Farmers' Union, called for more support for growers, describing it as "ridiculous" that the horticulture sector was not included in the government's support scheme for energy-intensive industries.
However, farming minister Mark Spencer told the BBC that the shortages were the result of "weather events in other parts of the world" rather than the challenges facing UK producers.
FTSE 100
The UK's top share index, the FTSE 100, was down 39 points at 7,937 shortly after opening this morning, following yesterday's 36-point loss.
Brent crude futures slipped 0.43% to $82.63 a barrel.
Companies reporting today
- Full-year results: Grafton, Lloyds, Rio Tinto