At the salon, children are not allowed to scream, roll around on stools, rip magazines or treat their property as a playground, the announcement said.
Edwards said parents could pick up the bill for destructive children if they didn't take reasonable care.
"The shop can recover all its direct losses for damaged stock if you didn't take reasonable care or adequately supervise your children," she said.
"The amount is usually the retail price of the product including any loss of profit from the shop now being unable to sell it. You may also have to pay for any damage to shop fittings caused by your actions, She said.
However, you were not liable to pay if an event outside your control led to or contributed to the damage.
"A sign like 'If you break it, you buy it' may have no legal effect. Whether you have to pay the shop for a breakage will depend on whether you failed to take due care.
"But, a shop can display a sign warning you to take care around goods that they know are fragile and need careful handling."
Salon owners Ritchyrd and Jess Hirst told the Herald children's haircuts were done with just as much care as for adults - and cleaning up after children took more time and resources.
They saw no problem with covering the extra cost by increasing kids' prices.
"After 24 years of hairdressing our tools have been dropped and broken, scissors chipped magazines ripped, Eftpos machine used as a toy.
"Screaming kids flying through the salon on our stools which break the wheels, and smacking into the walls damaging the paintwork, falling headfirst on to the floor ... snot rubbed into our chairs, dirty fingers rubbed into our windows and mirrors and food smeared on the floor."
That behaviour put their business at risk, they said.
"Health and safety plays a big part. We can lose business from valued customers coming to us for a relaxing experience.
"We also find ourselves in an awkward position having to ask the parent or guardian to please sort their child out."
As parents themselves they knew "it can be tough taking children out especially into a professional, mainly adult environment".
Edwards suggested a trip card for children to encourage good behaviour.
"Nine cuts, get one free or maybe when parents go to pay, they could offer a 50 per cent discount if the kids have been well behaved."