Gardens in the city might mean a window box, courtyard or a teeny weeny entrance lawn to the front door but they are still a haven for those gardening enthusiasts.

Anyone who has a small garden in a big city should take some advice from Matt James, presenter of The City Gardener on Channel 4. He should know all about making the most of small gardens.

"I have the tiniest space imaginable for my garden. I live in London with a garden 'up there' on a balcony," he says.

"I get my digging fix at college or at my mum's, but I don't feel downhearted. Even a windowbox can be your own little acre."

His first book, The City Gardener, inspired many to tear themselves away from the sofa and create their own outdoor haven in town, and he now moves one step further with The City Gardener: Urban Oasis (Collins, £17.99) to help gardeners create a little piece of paradise in their chosen style.

One of the most difficult decisions when creating your city garden is deciding which style of garden you would like, whether minimalist, modernist, Japanese, Mediterranean, cottage or classic.

James advises: "Keep it simple. Remember that the smaller the space, the simpler the design should be."

Start collecting pictures from magazines and papers that catch your eye, without trying to categorise them into particular styles. Once you have enough pictures, pin them to a large piece of hardboard to create a 'mood board' which will illustrate the type of style you'd like for your own garden.

The mood board should point towards one style, or maybe two, but you don't have to stick to one theme or it may begin to look contrived. And you can create most moods with a smaller plot, just scaling down the plans and incorporating smaller plants.

Here are some of the key garden styles to help you collate your ideas:

Classic: Its roots are in Greek and Roman times and there won't be a blade of grass out of place in a truly classical garden. Even unruly plants are disciplined and have restricted outlines. Classic gardens have clean straight lines, lots of squares and rectangles, clipped box and topiary, an air of formality which is not particularly child-friendly. Modern formal gardens use water in geometric pools and metals like steel and aluminium in structures.

Cottage: Informal, lush and overflowing with scented plants like roses or honeysuckle around the door. Their informal borders are stuffed with old fashioned roses, catmint, lavenders and pinks, along with sweet Williams and many plants which self-seed everywhere. Plants are crammed into borders where there's space. The mood is tranquil and tolerant and mistakes in this garden are just accepted. In small gardens, this is achieved by planting smaller perennials, climbing plants and using materials such as brick and gravel, terracotta pots and anything worn and weathered.

Japanese: Utilising clean lines and the careful placement of a small number of features, Japanese gardens suit small enclosed city gardens. They are visually tranquil and make use of texture including slate, bamboo, maples and bonsai, slatted wood furniture and pretty containers. The key to this look is restraint - don't plant too much in a small area.

Modernist: They echo the new architecture of the house and take it into the garden. All non-essentials are stripped away and asymmetrical designs are everywhere. But you have to carefully consider the character and age of your house and proportions of windows and doors so that these dimensions can be incorporated in the garden. It's ideal for city people who want outdoor rooms with a strong link to the functional rooms in the house. Plants tend to be architectural - phormium, cordyline and euphorbia are ideal.

Minimalist: Those which are full of stainless steel and shiny surfaces get their roots from the modernist style but are also greatly influenced by the restrained Japanese garden. They can be formal or informal, but 'less is more' is the key. Planting is either of one species in a group or one plant in isolation. Colour is subtle, usually of a variety of tones of a single colour. Such designs are low maintenance and suit busy city people.

Deconstructivist: Ultra-contemporary, featuring sharp angular forms or a mixture of angles and curves. Cutting-edge materials such as glass, metal, and plastic are used and often the planting actually plays second fiddle to the design. Says James: "I like to think of these designs as playthings for designers who like to challenge themselves to come up with something shocking and new to set us all talking." The danger of the deconstructivist garden is that by this time next year it may well be looking dated.

Once you have chosen your style, you can set about drawing a scale plan, but keep it simple, particularly if you haven't much room.