Mahaha Mphou of Lesotho does not know much about global economics, but she does know how to grow vegetables.

She and the rest of her family of 10 have become some of the most enthusiastic evangelists for a home-grown idea that has almost certainly saved them from starvation.

They are now thriving on what have become known as "keyhole gardens". They are round gardens of about two metres (6.5 feet) in diameter and raised to waist-height to make them easy for the sick and elderly to work.

Inside, the garden-beds are layered with tin cans, mulch and ash which together provide the nutrients to make the gardens extraordinarily productive.

Ntsie Tlali from Care, the non-governmental organisation behind the gardens, believes they are revolutionary.

"As you can see, (Mahaha's family) has three keyhole gardens and that's more than enough to supply all 10 of them with all the vegetables they need, and with some left over to sell. It's changed their lives."

Because they are protected by the stonework, the rich soils are safe from erosion.

They retain moisture far more effectively than land farmed by traditional farming methods, and they are compact enough to turn the tiniest plot of land into productive agriculture.

Story and photo source: "Lesotho gardens relieve food crisis", BBC