Garden supplies and vegetable seedlings are the latest target for panic buying and people in isolation keeping busy, as concerns about the Covid-19 coronavirus grow.

Photo: RNZ / Robin Martin

First it was supermarkets being cleaned out of toilet paper and hand sanitiser, but now it seems spooked shoppers have home-grown vegetables in their sights.

Garden centres say seedling sales have gone through the roof while nurseries are scrambling to meet demand.

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GardenBarn in Masterton sold out of seedlings on Wednesday.

Located near New Plymouth and Waitara, Big Jim's Garden Centre manager Chantel Bell said the last week had been bedlam.

"Veggie seedlings are flying out the door. We have doubled what we would normally order so we order twice a week but we are doubling what comes through the door in regards to veggie seedlings.

"All brassicas. The caulis, the broccolis, lettuces. Anything like that."

Bell said first-time gardeners and green-thumbed veterans alike were talking about Covid-19.

"They're just getting ready just in case there's a shortage of veggies on the market, that sort of thing ... if they're in isolation it's something to do in their garden all those sorts of things and panic buying maybe."

Bell said the seedlings on offer were less well developed.

Leslie Lewis, who was shopping at Palmers Garden Centre in New Plymouth, had certainly noticed.

"We need to get some silverbeet in and some spinach, but unfortunately it looks like they've been well cleared out and there's just punnets ... little tiny ones which is not really good to me."

Photo: RNZ / Robin Martin

Over the road at Mitre 10 Mega, Mike Anderson was also stocking up, and reckoned seedling supplies were dwindling.

"I've always had a garden and I suppose I'm prompted to increase it slightly at the moment in order to be self sufficient.

"I think I've got enough fresh vegetables in my garden to keep me going for about two weeks for me and my family."

Across town at Fairfields Garden Centre, Ari Whakaari was shopping with her partner and young baby, preparing to put in their very first veggie garden.

"I've just come to get some vegetables so I can plant them and make my own vegetable garden.

"It's because of the virus because the supermarkets are getting cleared out so I thought if I had a back up that would be great."

Whakaari was not doing things by halves.

"I've got some broccoli, kale, lettuce, beetroot, beans, parsley, spinach and leeks but there wasn't actually much here - quite a lot of it had already been taken."

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Zealandia Horticulture is one of the country's largest suppliers of seedlings.

General manager Pedro Wylaars said they were being hit by a double whammy of an increase in gardening at a time of year when it usually dropped off.

"Typically at this time of the year we're seeing a reduction in the volume [of seedling orders] that's quite dramatic.

"Going into the autumn-winter period, sales are quite minimal and so there's probably a bit of a doubling effect."

"There's more people probably thinking of doing some gardening ... [when] gardening is starting to flatline and drop right off."

Wylaars said lower-grade seedlings were being supplied to garden centres, but they would grow just fine.

He said commercial growers had been unaffected by the spike in retail demand.