The jungle look: Anna Pavord is captivated by a magnificently theatrical front garden in Walthamstow

Many roads in suburban London have a similar feel about them: terraced or semi-detached villas of the late Victorian, early Edwardian kind, the front gardens too often obliterated by concrete slabs and wheelie bins. Maynard Road in Walthamstow is different. The first thing you see, turning into the street from Beulah Road, are two brick flower beds, magnificently planted with Brussels sprouts and sunflowers, red cabbage and bright yellow African marigolds, nasturtiums, lilies, tomatoes, Jerusalem artichokes, borage and pumpkins. The beds stood alongside half a dozen tatty garages set in a block on the right hand side, but this didn't look like council work – too eclectic. If not them, who?

The answer came as I dropped down the hill and saw on the left-hand side of the road, a house completely smothered with things to eat. Strawberries dripped down from pouches set either side of the little gate. A plum tree obscured the bay window of the front sitting room. Cucumbers cascaded on to the pavement from a clay pot set into the boundary wall, a pumpkin had started a determined assault on the roof. Peaches and a nut tree made a notional boundary between this garden and its neighbour.

This magnificently jungly, wonderfully surprising front garden belongs to Don Mapp and it was he who galvanised the street to spruce up the garage planters. He's got his eye on a trophy from Britain in Bloom. Last year, Walthamstow won a silver-gilt medal. This year, Mapp's going for gold.

Mapp came to Britain from Belize when he was 14 and has never forgotten the vividness and fecundity of the place where he was born. He's been in his house about 20 years and started gardening seriously 10 years ago. "I like growing unusual things," he explained, "but the food theme is new. I did the front garden like this last year and people seemed to like it, so I thought I'd do it again." He makes it sound so normal.

But you have to work very hard to shoehorn almost 70 different kinds of fruit, vegetables and herbs into a space no more than 6m x 4.5m (20ft x 15ft). Balanced on top of the bay window is a lemon tree with some showy lemons hanging from its branches. "Well, actually I wired those on. Just while I'm waiting for my own fruit. It makes it more interesting for people passing by, doesn't it?" Behind the lemon, a sunflower stretches towards the eaves, and there are pots of Italian black kale (cavolo nero), a fig tree, nasturtiums and peas dripping down over the window below. Even onions.

How did he keep it all watered, I wondered. He leans out of the bedroom window, he said, with a squeezy bottle fitted with a long pipe. In the spring, he adds Miracle-Gro, in the autumn Phostrogen. Behind all the growth, only tiny remnants of the white-painted house can still be seen. Next month, I suspect they too will have disappeared under crops of tomatoes (they grow in hanging baskets and plastic pouches fixed to the house) and the fearsome number of marrows and squashes that Mr Mapp has set against the foot of the wall. His favourite is a Sicilian squash with fruits that can grow up to two metres long (Seeds of Italy stock it – look for Squash Serpente of Sicilia).

It's obvious that the plants balanced on top of the bay window should be in pots, but so, it turns out, is everything else in the front garden – the apple tree by the gate, the olive tree close by it, the pomegranate, the pear tree, the blueberry balanced on a high stand. Even the beautiful cauliflower, which I had been admiring just the other side of the garden wall, is in a pot. And the Cape gooseberry.

Like a stage set, the whole garden is dismantled in winter. Some trees move into the back garden with tender plants stacked on shelves in the glassed over section of the side passage that runs alongside the house.

All the plants at ground level are linked by a spaghetti trail of leaky hose. The water is switched on for three minutes six times a day. Most of the plants, he says, are happy with this regime. Broad beans flourish. Garlic swells in the long narrow box fixed to the inside of the boundary wall. Runner beans have already joined together to make an arch over the pathway. The whole of the boundary along the path is hung with boxes of herbs. Only the sage objected to the watering regime and began to rot.

Fixed high against the house on the other side of the path is a hydroponic growing system that looks like two fluorescent light strips fixed together. It is one of Don Mapp's few failures. "The reservoir of water and food is in the bottom tube and the plants are supposed to grow in the top one," he explained. "You pump the water through the roots eight times a day, 15 minutes each time. But I haven't got the balance right. The roots keep rotting."

If you push on through the glassed-over passage, past a pink mandevilla so perfect you think it can't be real, you emerge into a back garden as wonderfully overfilled as the front garden, just a bit larger. The food theme is left behind, though, and here you are in a Central American hot spot, with vast mirror carp, koi, rudd and tench swirling about in a rectangular tank. A tall tree fern stands beside a surprising and brightly-tiled hot tub set in the middle of the plot. "Actually," explains Mr Mapp, "I wanted the tree fern in the middle of the Jacuzzi with the fronds spreading out over it, but it was too complicated."

Instead, he's wired huge fleshy succulents to its trunk (aeoniums and aechmea) and given it tropical strelitzia and iochroma for company. "Green Goddess" arum and angels' trumpets in white and yellow rear out of a carpet of tolmiea. A potted yew tree, clipped into a narrow pyramid is raised high on a stand in the back corner where it manages to look as exotic as a palm tree.

On my return from Walthamstow, I got off the tube at Oxford Circus and walked up Portland Place towards Broadcasting House. On the pavement alongside the BBC building were two enormous planters handsomely built of Portland stone. But what were they planted with? Nothing, except a thick mulch of rubbish: free sheets, coffee cups, water bottles, sandwich wrappers. Don Mapp – these planters need you.

The garden at 47 Maynard Road, London E17 9JE is open tomorrow (11am-6pm) and every following Sunday until 7 August. Admission is £2.50. Take the Victoria Line to Walthamstow central station. It's just a 10-minute walk from there.