Using vending machines to sell their potato crop has paid off for growers Pete and Euan Grewar of Perthshire, Scotland.

The potato-growing cousins have installed 4 vending machines in several Scottish locations and are considering more. "The core of our business is certified seed and potatoes for supermarkets, and that will continue," says Euan. "But the vending machines are a great add-on, a logical diversification."

In addition to the Grewars' potatoes, the machines are stocked with fresh eggs, brussels sprouts, strawberries, carrots and onions. Interestingly, the Grewars have discovered that customers prefer unwashed produce. "One of the most common comments we got was that customers like dirty carrots. They don't want us to clean them," says Euan.

The farm-food vending machines are manufactured by Roesler in northern Germany and are being used throughout Europe for eggs, vegetables and potatoes. "Vending machines are the ideal solution to replace honesty boxes for farm-gate sales, where would-be customers walk off with eggs or produce without paying," says John Gordon, an egg producer in Scotland.

Roesler vending machines cost from $7,500 to $16,000, depending on whether a unit is refrigerated. The Roesler vending website states that the machines are made of rust-free high-grade steel and are weatherproof. Machines can be equipped with a cash-card scanner.

Pete Grewar says the brothers are contemplating adding more vending machines. "Obviously it doesn't make sense to have one machine in Aberdeen, Edinburgh and Glasgow, but 6 to 10 in each city might be efficient." He says they're also considering franchises for the vending business.

The business uses Facebook and Twitter for promotion and the cousins say they value interaction with customers and customer feedback.