One of the world's major kale seed suppliers says it has run out of every variety of the trendy vegetable.

"You could describe it as embarrassing to us, but it's just one of those things that's happened on a global basis," Tony Hubbard from Bejo Seeds, which is based in the Netherlands, said.

"It's caught us out well and truly, we put our hands up to that."

Mr Hubbard runs the company's Australian office and has been in the seed business for 44 years.

He says while he has seen individual vegetable varieties take off, he has never seen a whole crop boom like kale has.

Farmers have also been struggling to keep up with demand for kale, which is a member of the cabbage family.

Fifth generation growers Deborah and Darren Corrigan planted 1,500 seedlings a couple of years ago as a trial, after watching the vegetable take off in the United States.

They are now putting in 150,000 every week at their Clyde property, south-east of Melbourne.

"It was crazy," Ms Corrigan said.

"I was ringing around Australia to try and get plants to bring back into Victoria to grow."

Ms Corrigan says they have been going to extreme efforts to ensure a healthy supply of the vegetable known as a "superfood".

"We were adding extra fertiliser, we were doing everything we can," she said.

"It was really exciting but really scary at the same time."

Australia's biggest kale growers says its popularity is off the charts

The Corrigans are among the biggest growers of kale in the country, supplying both the major supermarkets.

Kale farmer Deborah Corrigan checking on her crops. Ms Corrigan says the prospect of running out of crops is "scary". ( ABC Landline )

They grow three types - green curly kale, red curly kale and the flatter-leaved Tuscan kale.

Brad Gorman, who runs the Coles Fresh Produce division, says he has also been surprised by the response.

"Kale's growth has been off the charts. It is by far our fastest growing product," he said.

"Kale's been around for three years and for a product to be growing at this rate after that amount of time I think is almost unprecedented."

While kale is a novelty for many Australians, it is not a new crop.

Until the Middle Ages the frost tolerant green was the most widely eaten vegetable in much of Europe and has remained a staple in some countries including the Netherlands and Germany.

"It's one of the main vegies in the winter," long-time kale grower Joh Bruynen said.

"It can be harvested right through the winter. You take the snow off the bush and shake it and then you cut it off."

Kale pioneer waited for decades for the vegetable's health benefits to be confirmed

Joh Bruynen is one of the pioneers of kale in Australia importing his first seeds from the Netherlands, where he was born, in 1956.

"I had trouble selling it because they didn't know what it was," the 83-year-old said.

"I brought it to the market and the butchers bought it to decorate their shops because it looked like parsley which they used in between the meat."

His son Steve Bruynen has taken over the family's market garden at Pearcedale in Victoria and has no such trouble finding buyers.

"I've had to drop growing red cabbage and leeks have gone because I need the ground to grow the kale," he said.

While the Bruynens have been fans of kale for decades, they did not know how rich the vegetable is in anti-oxidants and important minerals until a few years ago.

And it is kale's reputation as a very healthy food that has sparked the current boom and shortage of seeds.

Mr Hubbard says he hopes more seeds will be available by September or October.

For more on this story watch Landline at noon on ABC.