The planned date to leave the EU coincides with the UK's annual period of low crop production, which is putting the nation's food security at risk.

For UK farmers, the planned Brexit deadline couldn't come at a worse time. 

March 29 coincides with a period known as the 'hunger gap' or the 'hungry gap' -- when UK farm produce is at an annual low and imports from the European Union, as a result, increase. 

In the event of a no-deal Brexit, this could be disastrous for the nation's fresh food security. Mark Carney, the governor of the Bank of England, has said food prices could rise by up to 10 percent without a deal. 

So-called "Brexit preppers" have taken to stockpiling food, medicine, and toiletries as insurance. However, fresh produce cannot be stockpiled and so, for some retailers, this presents an opportunity. 

Seed importer Paolo Arrigo has been selling a year-round supply of easy-to-grow seed packets called the Brexit Vegetable Growing Survival Kit from his London-based family business. Arrigo launched the survival kit in response to the needs of the 48% Preppers group on Facebook, which currently has more than 10,000 members. 

"Our regular customers are buying their seeds as normal but their spend has gone up," said Arrigo. "People who are buying [the kit] are mostly new gardeners. They've never grown anything before in their lives. It's been bought across the political spectrum and by people very worried about fresh food supply."

Helena, who lives in Cardiff and is a member of the group, has been stockpiling since November. "All I have done is creating a bit of an insurance policy for myself if there are any shortages. I have prepped for about three months' worth of human food and a year's worth of dog food. We're the world's sixth-largest economy, we shouldn't have done this."

The hunger gap 

"What Brexit has done is it has made people realize, actually, where do my vegetables come from?" said Arrigo.

Due to the UK's climate, between the colder months of April and June, fresh produce is low. Winter crops are running out and new vegetables aren't ready to be harvested until June.

Fully stocked supermarkets may give the impression this is not the case, but usually during this period, the UK imports most of its farm produce from the EU. Walk into any supermarket and a closer look at the labels show products from Portugal, Italy or France. Spain and the Netherlands account for 69 percent of the UK's import of fresh vegetables annually. 

"In March the situation is more acute as the UK produce is out of season: 90 percent of our lettuces, 80 percent of our tomatoes and 70 percent of our soft fruits are sourced from the EU at that time of year," wrote the British Retail Consortium, a trade association, in an open letter to MPs.

The uncertain Brexit outcome means the way fresh produce is imported during the hunger gap may have to change. Usually, groceries imported to the UK arrive without trade costs or customs duties. In the event of no deal with the EU, this could mean delays in food being transported and an increase in price due to higher demand. This potential disruption in the supply chain is a reason why some have resorted to stockpiling seeds to grow their own vegetables. 

Seeds as insurance 

Despite the increase in stockpiling, from individuals to supermarkets, a spokesperson for the Department for Environment, Food and Rural Affairs (DEFRA) told CGTN "there is no need" for it.

"We already have a high level of food security in the UK, with half of the food we eat produced on our shores. Our food industry is also highly resilient and well versed at preventing disruption," said the spokesperson. 

Yet this security doesn't account for fresh produce during the hunger gap, when fresh produce is at its lowest and imports are at their peak. 

Brexit preppers "are buying seeds because they don't want an interrupted supply of vegetables," said Arrigo. 

"Everything that you eat comes from seeds, directly or indirectly. Seeds are the biggest thing on the planet that has never been spoken about."