A garden measured in pots, not acres

You do not need a meadow to make a difference. A courtyard, a balcony or a narrow strip beside the back door can feed a surprising number of pollinators, because bees and butterflies work to a different map from ours. What they need is reliably simple: flowers open for as many months as possible, somewhere to shelter or nest, and clean water. Get those three roughly right in a small space and the visitors will find you.

Think of your plot as a service station on a much longer route. A worker bumblebee may travel several hundred metres from her nest, visiting many flowers in a single trip, and she learns routes worth repeating. The key word is abundance. One generous pot of catmint is a destination; a scattering of single plants is a distraction. In a small garden, plant fewer varieties and plant them thickly.

Nectar from March to October

Pollinators starve in the gaps, so aim for a continuous supply rather than a June flush. Build your planting list around these reliable performers:

• Early spring: crocus, pulmonaria, hellebores, mahonia, flowering currant, aubrieta and wallflowers.
• Late spring: alliums, chives, comfrey, thyme, honesty and forget-me-nots.
• High summer: lavender, catmint, oregano, salvia, borage and marjoram.
• Late summer: hylotelephium (the old sedum), echinacea, helenium, verbena bonariensis, single dahlias and rudbeckia.
• Autumn: asters, single-flowered dahlias and ivy, which is a genuine late-season lifeline when little else is in flower.

Two rules keep this manageable. First, choose single, open flowers; double blooms often hide their nectar and give insects nowhere to land. Second, plant in clumps of three or more of the same thing, so a bee can work efficiently without flying between strangers.

Culinary herbs do a great deal of the heavy lifting, and they earn their keep twice over. A pot of oregano left to flower is one of the best pollinator plants you can grow, and thyme, sage, chives and mint are close behind.

More than nectar: nesting and caterpillar food

Butterflies are only half the story. Caterpillars need to eat, and most of them are fussy about which plants they will accept. If you want butterflies rather than just visitors passing through, provide a few larval food plants:

• A patch of nettles in a sunny corner, kept in a pot if you are worried about spread, feeds peacock, small tortoiseshell and red admiral caterpillars.
• Buckthorn supports brimstone, while holly and ivy are the food plants of the holly blue.
• Bird's-foot trefoil and red clover suit common blue, and a little uncut grass helps speckled wood and meadow brown.
• Leave a patch of bare, undisturbed soil for ground-nesting solitary bees, which are far more numerous than honeybees and excellent pollinators.
• Add a bundle of hollow stems or a small block of drilled logs, facing south and sheltered from rain, as nesting sites for solitary bees.
• Keep a log pile or a leaf-litter corner. It looks untidy for a fortnight and then looks like a garden with a purpose.

A shallow dish does more than you would think

Water is the detail most small gardens miss. Bees drink, and on hot days they carry water back to cool the nest. Butterflies, particularly males, gather at damp ground to take up salts and minerals from the soil, a behaviour called mud-puddling.

The simplest answer is a saucer of pebbles or small stones sitting in water, filled only to the rim so insects can land safely and drink without drowning. Refresh it every day or two in warm weather, and tip it out if it turns green. A shallow tray of damp sand, or a bare patch of soil kept moist, will also draw butterflies. Site it near nectar plants but away from where cats sit, and you will see far more activity than you would expect from such a small addition.

Leave the sprays on the shelf

Every pesticide is a pollinator problem, including the ones labelled natural. Pyrethrum-based sprays kill bees on contact, and slug pellets are lethal to the ground beetles and hedgehogs that would otherwise keep slugs in check. Weedkillers strip out the very plants — dandelions, clover, bird's-foot trefoil — that feed insects early in the year.

Learn to tolerate a few holes instead. A chewed leaf is evidence that your garden is working. A dandelion in April is a meal, not a weed. If you must intervene, use a jet of water, a barrier or your fingers, and accept that a garden without any nibbled foliage is a garden without much life in it.

A few habits worth keeping

Small gardens respond quickly, so a little consistency goes a long way.

• Delay the tidy-up. Leave seedheads and hollow stems standing through winter and cut back in late March or April, once the hardest frosts have passed.
• Let one corner go wild. An unmown patch or a nettle bed gives cover, nesting sites and food.
• Plant in pots if that is all you have. A sunny windowsill of herbs, or three lavender pots along a wall, genuinely counts.
• Keep the water topped up and clean, especially during dry spells in July and August.
• Sit and watch. Note which flowers the bees return to and plant more of those next year.

Within a season or two, a small, scruffy, nectar-rich patch will out-perform a manicured one many times over. The hum of a summer afternoon is the reward, and it costs very little to earn it.