Planting on a balcony is a bit of a challenge, but battling the elements is worth the results, writes JANE POWERS

NOSINESS IS ESSENTIAL to gardeners. We like to lean over people's gates, and rummage around in their flower beds and greenhouses. It's one way of learning how to grow things, or about what plant works where. But there is a group of gardeners who it doesn't help. I'm talking about balcony gardeners. They can walk along the street, head in the air, or crane their necks in double-decker buses, trains and trams, and all they can see are tantalising glimpses of plants. Learning what to grow - and how to grow it - is not easy for a person whose horticultural real estate is on the side of a building.

For plants, a balcony is the equivalent of the side of a mountain: weather is more severe than at ground level. Wind can be stronger, which means plants may dry out quickly, or be prone to toppling over, or can even be pulled out of their containers. The quality of light may also be extreme, depending which way the balcony faces. If it is north facing, there will be little direct sunlight, whereas if it looks towards the south, there will be many hours of light and, on sunny days, baking heat. Easterly or westerly aspects are less demanding. Neighbouring buildings can also cast shadows or create wind tunnels.

But don't be put off by this. There are plants that will grow in all conditions. Furthermore, a bonus of high-rise gardening is that the scourges of ground-level growing, slugs and snails are unlikely to be present - unless they, or their eggs, arrive as passengers in a container.

Before you start gardening on the balcony, make sure it is safe to do so. Is the structure robust and secure enough to bear the weight of planters full of potting medium, especially after they have been watered? Also, remember, a falling pot can be a deadly missile, so you may need to fit railings, tensioned wire, or some other system to prevent plants careering overboard.

If the spot is particularly breezy, consider erecting mesh or trellis to filter the wind. Don't be tempted to put up a solid panel, as this will cause the breeze to buffet about. The aim is to diffuse its power by offering a permeable barrier. While you're in handyman mode, you might fit some trellis for climbing plants, or hooks or holders to attach pots to the walls.

Larger containers need watering less frequently than small ones, so think about growing plants in sociable groups, rather than as singletons in separate quarters. If your containers are deeper than you require, fill the bottoms with pieces of polystyrene, or with empty plastic drinks bottles (put the lids on to prevent them squishing). No one will know what's underneath the surface. Also, you'll need less compost, and the weight will be considerably lessened.

Soil-free compost is lighter than mixtures that are based on soil, such as John Innes. Peat-based composts are the more readily available of the soil-free kinds. If you don't like using peat for environmental reasons, the best peat-free medium available (in my experience) is the New Horizon range from William Sinclair.

Lightweight composts may need regular feeding and more frequent watering than the heavier soil-based types. Add water-retaining gel granules to boost their moisture-holding capacity. Mulching the surface, with gravel, expanded clay pellets, corks, seashells, or whatever whimsical material you fancy, will slow down evaporation.

To choose suitable plants, first determine whether your balcony is predominantly sunny or shady.

Shady balcony

Perennials and low-growing plants: ferns, hosta, lilyturf (Liriope), mint, parsley, ivy, periwinkle (Vinca), pheasant grass (Anemanthele lessoniana). Shrubby plants: box, Euonymus fortunei and E japonicus, fatsia, skimmia.

Sunny balcony

There are hundreds of plants that are happy in pots in bright and warm conditions. Look for species that are native to sunnier climates, such as California, the Mediterranean and Australia. Their foliage is adapted to conserve moisture, and to reflect light, and may be small, needle-shaped, leathery, shiny, blue-tinged, grey, hairy or suede-like - or a combination of the above.

For a sunny spot, the best plants are succulents such as agave, echeveria and sedum. If you can give them enough water, tomatoes and chillies will also do well. Here are a few other candidates.

Perennials and low-growing plants: agapanthus, Allium cristophii, sea pink (Armeria maritima), cupid's dart (Catananche caerulea), Convolvulus sabatius, Verbena, Mediterranean herbs, grasses such as Carex, Festuca glauca and Stipa.

Shrubby plants: bay, rock rose (Cistus), cordyline, fuchsia, griselinia, hebe, juniper, olearia, olive, phormium, pine (small varieties), pittosporum, Yucca gloriosa and Y filimentosa.

Today, 12-4pm, fourth annual open day at South Dublin Allotments Association at Friarstown Allotments, Bohernabreena, Tallaght; southdublinallotmentsassociation.ie