Supermarkets have limited the number of lettuces each customer can purchase in stores and iceberg, sweet gem and romaine varieties have been taken off sale completely by some online.
An extreme mix of drought followed by flooding and freezing conditions has severely affected growers in southern Spain, while poor conditions have also hit farmers in Italy, Greece and Turkey.
Dieter Lloyd, spokesman for the Leafy Salads Growers’ Association, said: “I think people are getting very surprised by the notion of rationing.
"But generally people don’t buy three heads of iceberg, or six packs of baby gem.
"The reason they are doing it (rationing) is because grocers, wholesalers, restaurants and hospitality outlets were going to the retailers and buying trays of produce.
“The retailers are trying to curb that because they want the produce to be available for customers rather than the hospitality industry or the wholesale market or greengrocers.”
A spokesman for Asda said it was doing everything it could to support its growers and bring them back to full supply as soon as possible.
A Morrisons spokesman said: “Our availability of broccoli and iceberg lettuce is good. However, other businesses are experiencing shortages and we have seen some bulk buying in our stores.
“We have therefore had a cap on sales of broccoli and iceberg lettuce to ensure we maintain good supplies for our regular customers."