Victor Matioli's organic pumpkins are plump, his coriander aromatic and his spinach "very soft, sweet, and tasty". His half-acre farm is a former rubbish dump in the heart of east Africa's biggest slum.
The unlikely story of Kibera's first "organic" farm - its only farm of any scale - has its roots in the chaos that gripped Kenya at the start of the year. For weeks the sprawling, densely packed slum, home to up to a million people, was gripped by ethnic clashes and street battles between riot police and protesters demonstrating over flawed presidential elections.
Among those concerned about a looming hunger crisis was Su Kahumbu, managing director of Green Dreams, one of Kenya's pioneer organic produce companies.
Initially, she hoped to organise a mass distribution of seeds to small-scale farmers in the Rift Valley to enable them to plant before the April rains. After a lack of funding halted the plan, a friend told her about a group of young, unemployed men in Kibera who wanted to learn how to farm - inside the slum.
Photographs of their would-be vegetable patch did not inspire confidence. "There was so much garbage there I thought, 'You must be joking'," said Kahumbu.
A rectangle of land bordering the railway line that cuts through Kibera, the proposed farm was being used as a refuse dump by nearby residents.
Piled high were plastic cartons, cans, broken bottles, chicken and goat bones, as well as innumerable "flying toilets" - polythene bags filled with human waste, a grim reminder of the slum's lack of sewage facilities. But when Kahumbu saw the enthusiasm among Matioli's 36-member Youth Reform Group, she agreed to help them get started. The men, mostly in their 20s, some having served jail terms, set about cleaning the site in late April.
Rather than simply dumping the rubbish elsewhere, it was compacted and tied down under tarpaulins on one side of the plot. The newly revealed soil still contained traces of refuse, mainly old strips of plastic, and Kahumbu sent samples away for analysis. Meanwhile, her brother laid down a network of drip-irrigation pipes linked to a water tank.
The soil tests revealed high, but not dangerous, levels of zinc, which could be drawn out by planting sunflowers among the vegetables. Still, Kahumbu felt that it would be wrong to teach the men conventional farming methods.
"The toxin levels in Kibera are already high and I did not think it was fair to add to them," she said. So, it was agreed that, soil quality and surroundings aside, Kibera's first modern-day farm would be organic. Fertiliser would come from vegetable scraps turned into compost, and from plant-nourishing "worm juice" produced by the earthworms kept in a half-barrel of soil. Within two months of planting, the first vegetables were successfully harvested. The farmers buy some of the produce; the rest sells swiftly within the slum.
Netting 10p for a cabbage and £1 for a pumpkin, Matioli's collective made a profit last month - a modest sum, but one that made him confident of the farm's sustainability. "People here are really interested in learning about our organic methods," said Matioli.