Some seed suppliers in New Zealand and Australia have pressed pause on trading after being overwhelmed with orders 10 times higher than normal.

New Zealanders are halfway through a strict four-week lockdown, in which they are not allowed to leave their homes except to buy essential supplies or to exercise locally. The restrictions are among the toughest in the world, but as a result, new cases of coronavirus have begun to decline.

Dr Ashley Bloomfield, the director general of health, has repeatedly encouraged Kiwis to get exercise through “gardening”, and the advice has been taken to heart.

King Seeds, the country’s largest seed supplier, has temporarily suspended online ordering after experiencing 10 times its usual business.

Many Kiwis appeared to be stockpiling seeds for summer, owner Gerard Martin said, or planting anything and everything out of panic, including watermelon, tomato and basil crops on the cusp of winter.

“They [customers] are buying a lot more than they normally would and buying things that they don’t need at this time of the year as well,” Martin told Stuff.

Egmont Seed company based in New Plymouth said there were would be “large delays” on all of its orders, as demand for seed was “unprecedented” during the lockdown, with ordering spikes beginning on the first day of lockdown.

“This time of year is normally our ‘quiet’ months,” the company said on its website.

“We are clearly not keeping up and clearly never will … PLEASE EXPECT DELAYS.”

In Australia, The Diggers Club, one of the country’s largest gardening clubs and seed catalogues, paused new product orders due to “unprecedented demand”. The company said on its website that while it had “a good supply … our priority is to reduce the extensive delays on existing orders”.

Eden Seeds, a popular heirloom seed supplier in Australia, has suspended orders until after Easter; while an email seen by Guardian Australia shows that Yates, a major supplier of seeds in both Australia and New Zealand, has been unable to deliver some current orders “due to unexpected demand”. On its Australian website, Yates suspended all new orders saying “we have completely sold out”.

Bronwyn Alder, from the independent plant shop Newtown Garden Market, experienced a run on seeds first hand. “It’s both the seeds and the edible seedlings,” she told Guardian Australia.

“We’ve had the phone ringing off the hook for people interested in growing seeds for the first time. There’s been so much new interest in gardening for edible plants. The amount of new gardeners who are interested in edibles is unparalleled.”

The market gets new stock at the beginning of every season, and they usually “have a decent supply in”. However, this year, “within a week and a half we had no seeds on the rack. We’ve been trying to order more, but our supply chain can’t get any more in. They’re struggling with the demand … I don’t think anyone was prepared.”

Alder does not believe her customers are hoarding seeds, however. “I think there are some people who are feeling fearful … about food security, and have a genuine interesting in growing their own for food protection. And I think there are people who are bored and want a hobby.”

She added: “The silver lining to [the coronavirus crisis] may be that 2020 is the year people’s gardens look great again.”

In New Zealand, seed companies said there was no shortage of supply and urged gardeners to buy normally, and only what they immediately intended to plant.

Online, membership of gardening groups has boomed, with people sharing lockdown ideas for weaving weeds into baskets, planting strawberry seeds scooped out of shop-bought strawberries, and growing new roots for supermarket lettuces and leeks.

“Planted on the very first day of lockdown we are now picking and eating mizuna and bok choy,” wrote one woman on the New Zealand Budget Gardening page.

“Silverbeet is ready too.”