Even the smallest balcony can become a refuelling stop for bees and butterflies. With a handful of well-chosen pots, a saucer of water and a bit of shelter from the wind, a bare ledge can turn into a genuine habitat — and you will usually see the difference within a single season.

Why balconies matter to pollinators

Rooftops, window boxes, courtyards and balconies form a patchwork of stepping stones across our towns and cities. In dense neighbourhoods, these pockets may be the only flowers for streets around, so what you plant genuinely matters. Bumblebees will happily forage at height, and many solitary bees, hoverflies and butterflies will use a productive balcony if it offers food, water and somewhere to rest.

You do not need a garden, a lawn or even much space. A metre of railing can support half a dozen good plants, and pollinators are far more interested in the quality of what you grow than in how grand it looks.

Choose nectar-rich flowers, not just pretty ones

The single most useful rule is to favour open, single flowers. Double blooms have often been bred so heavily that the stamens have turned into extra petals, which means little or no nectar and pollen. Bedding geraniums, busy Lizzies and double begonias look cheerful but feed almost nothing.

• Spring: crocus, grape hyacinth, wallflowers and winter-flowering heather in small pots
• Early summer: catmint, lavender, salvia, thyme, oregano and marjoram
• Midsummer: borage, calendula, cosmos, nasturtium, verbena, alyssum and single-flowered dahlias
• Late summer and autumn: sedum, asters, penstemon and Japanese anemone

Herbs are exceptional value. Thyme, oregano and marjoram left to flower will draw more bees than almost anything you can buy in a garden centre, and you can still pick a few leaves for the kitchen. Lavender and catmint are the reliable workhorses of a sunny balcony, flowering for weeks if you keep deadheading them.

Plant in generous groups, in generous pots

Pollinators find a bold block of colour far more easily than a single lonely plant. Group three or more of the same species together, or fill one long trough with a single variety. A 60cm trough of catmint will be visited many times more often than the same plant grown on its own.

Use the largest containers you can reasonably fit. Most perennials want at least 30cm of depth, and a 35–45cm pot holds moisture far better than a tiny one, which matters when you are out at work all day. Use a peat-free compost, add a handful of grit or gravel to the surface to slow evaporation, and raise pots onto feet so excess water can drain away.

Never use insecticide sprays, and check that plants you buy have not been treated with pesticides — some nursery plants carry residues that harm the very insects you are trying to help.

Provide shallow water

Bees need water to dilute honey and cool their nests, and butterflies will gather at damp ground to take up minerals. The problem is that a deep dish is a drowning hazard for a tired insect.

• Fill a shallow saucer with pebbles, marbles or corks so there are plenty of landing pads
• Top up so the water sits just below the top of the stones, never above
• Place it in dappled shade so it does not dry out by midday
• Refresh every day or two in warm weather so it stays clean and does not stagnate

If you have room, add a second, even shallower dish at floor level for beetles and other ground-dwelling visitors. In very hot spells, a small patch of damp soil in a pot of herbs will also be appreciated.

Create sheltered, sunny resting spots

Wind is the quiet enemy of a balcony. It strips warmth from a south-facing wall and blows small insects off course, so a little protection goes a long way. A woven willow screen, bamboo roll or even a row of tough plants such as rosemary helps, but keep it permeable — a solid barrier simply makes the wind swirl around the ends.

Aim for a spot that catches sun for at least four to six hours a day, ideally facing south or south-east. Then leave one corner slightly untidy. A bundle of hollow canes tied together and hung facing south makes a simple nesting site for solitary bees, and a pot of ivy or a small shrub gives butterflies somewhere to roost out of the rain. Resist the urge to sweep every fallen leaf away; a little leaf litter is shelter for overwintering insects.

Keep the season going

Bees and butterflies need food from early spring right through to autumn, so plan for a succession rather than a single glorious flush in July. There is often a lull in early summer between the spring blossom finishing and the summer flowers starting, so catmint, salvia and herbs earn their place by filling it.

Late-season nectar is especially valuable. Queen bumblebees need to build fat reserves before hibernation, so sedum and asters are worth their space. Keep plants well watered and give them a weekly liquid feed — stressed plants produce less nectar. Deadhead regularly to prolong flowering, and in winter leave seedheads and stems standing until late spring, when the new growth begins.