West Australians who buy seeds from interstate by post will soon be hit with a quarantine inspection fee of $56.

The Department of Agriculture has confirmed it will extend a fee, which previously only applied to commercial importers, to anyone who brings seeds into the state.

The department's spokesman Greg Pickles says quarantine officers will inspect parcels for contamination and send the recipient an invoice.

He says individuals can avoid the charge if they buy seeds from businesses which have opted to pay the fee for their clients.

"We're trying to minimise the impact on private importers by encouraging interstate suppliers to enter into a special arrangement and accept the inspection charges on behalf of the private importers," he said.

Mr Pickles says he believes the level of public awareness about the changes is adequate.

"The Biosecurity and Agricultural Management fees and charges determination was actually published in the West Australian government gazette on the third of May as part of that process," he said.

"We are then sending through some of the suppliers but then again it's very hard to notify everyone."

Mr Pickles says a press release has also been issued to try remind importers about the changes.

He says he does not expect the fees will encourage people who mail seeds to WA to make false declarations.

"I believe the public is well aware of the need to have high quarantine status in Western Australia," he said.

"The department will be continuing its surveillance of mail and parcel centres to prevent the introduction of those risk materials into Western Australia by post."

Mr Pickles has warned people who try to sneak seeds into WA will face penalties.

"Fines of up to $5,000 could be imposed on people who illegally import quarantine risk material by post," he said.

A sustainable growers group has criticised the State Government for not warning people about the new charges.

Permaculture West's Charles Otway says the department has missed opportunities to let people know about the changes.

"I ordered some seeds about a month ago that came through quarantine and they were stamped by quarantine," he said.

"It would've been logical for them to put a piece of paper in there saying, by the way, new fee structure coming in but that wasn't done.

"There's been no effort whatsoever."

Mr Otway says there is a risk the seed fees will discourage people from growing their own produce and will limit what's available in Western Australia.

He says private growers often shop online through interstate stores because they sell better varieties and a wider range of seeds.

"If you look at something like broad beans, there might be one variety in the hardware stores and there should be 20 or 30 varieties available at organic heirloom stores," he said.

"And, when you're talking about biodiversity and biosecurity which this is all about, surely we're not achieving that by limiting what we can grow."

The fees come into effect on Monday.