Demand for local food and a supercharged interest in gardening has combined with Brexit bureaucracy to create delays and a growing shortage of heritage and organic seed.

The shortage has further long-term potential to reduce the amount of plant biodiversity growing in the UK, thanks to renationalising a previously pan-European seed list without transferring all existing certified seeds.

The move, which according to seed suppliers has left off many heritage variety ‘staples’, means British small organic and heritage growers will have fewer seeds available officially, reducing the potential for locally-adapted and climate resilient varieties.

Heritage seed suppliers including Vital Seeds in Devon, The Seed Co-operative in Lincolnshire and Real Seeds in Wales all have daily caps on their websites, as they deal with a backlog and delays in orders from Europe due to new certifications and paperwork.

“Last year we had people put an order in January, and then order again in March because their veg box scheme had suddenly doubled in size. The demand for local food has gone through the roof, people want to know where their food is from,” said David Price, managing director of Lincolnshire-based The Seed Co-operative.

“Since lockdown, it has been absolutely crazy. Sales were up 600 per cent by last autumn on the year before,” he said. “Covid has definitely heightened people’s awareness of food issues, availability and provenance. Panic buying really hit home with a lot of people; it acted on this latent sense that people needed to do more to build their resilience.”

Fred Groom, founder of Vital Seeds, said everyone is “overwhelmed by orders”. “It’s a similar scenario in the conventional seed market. And we’ve seen US seed suppliers shut down as well,” he said.

“Brexit plus Covid has increased people’s worry, and the major panic was last March when over one weekend orders went crazy.”

Vital Seeds has seen orders quadruple in the last year and has expanded its outdoor growing space to coincide. But orders placed last summer with European suppliers are yet to arrive and Groom said “there are definitely shortages”.

Delays are being caused by a similarly huge interest in food growing across Europe, where demand for seed is just as high, coupled with a poor growing season in central Europe last year and teething issues around Brexit paperwork.

“The Brexit paperwork has been a complete nightmare,” said Price. “It comes back to being a small team; we don’t have someone sitting in an office dealing with Brexit. 20 per cent of our sales were going to the EU, predominantly to Ireland, but we’ve stopped all exports including to Northern Ireland. It was too complicated so we shut it down.

“You couldn’t prepare for it because there was no one to tell you definitively what to prepare for.”

The British seed sector imports around 80 per cent of its seed from overseas. The link with biodiversity and small-scale growers comes from the type of seed they use: ‘open pollinated’ refers to seed that is not commercially owned and can be saved for re-use. As a result, it is much more genetically diverse and likely to have adapted to unique local conditions, boosting both yields and climate resilience.

“Open-pollinated seed is designed and bred for organic systems and organic systems are designed for diversity,” said Price. “Diversity keeps the planet going; without it we are stuffed.”

The Seed Co-operative has sold out of organic broad bean seed, Price said, while Vital Seeds has sold out of their homegrown British tomato seed and won’t be restocking. Other staples such as the popular Black Beauty aubergine have not been added to the UK National Seed List, which could limit availability in the future.

Vital Seeds’s Ronja Schlumberger said: “The UK National Seed and Plant List really limits the availability, especially of rare or older varieties. The box schemes will suffer the most.

“We are seeing delays but it will be more about the limits on certain varieties. For instance, we can’t get Borlotti beans at the moment, which are such a lovely crop,” she said.

All EU countries have their own national seed list, which is also amalgamated into a common EU seed catalogue. “It was transferred in a mad rush to the UK national list, and there are a whole load of varieties that aren’t on the list. They didn’t think small seed suppliers would be that bothered and didn’t make a point of telling us,” said Price. “Tens if not hundreds of varieties could be lost.”

Amateur gardeners can save their own seed to preserve their own supply, but to help stem the wider shortage in open-pollinated seeds, professional growers are needed.

“It comes down to experienced growers who are able to branch out into seeds,” added Price. “Amateur growers won’t have the skills to do it at scale in a commercial way. If that doesn’t come through then yes, there is potentially going to be a bottleneck.”

“Things could change quite quickly if these growers come through. From one pack of carrots you can produce an awful lot of carrot seed.”