Why a window box can be a nature reserve

You do not need an acre of chalk downland to grow British wildflowers. A balcony railing, a doorstep, a tired old sink by the back gate — all of these can hold a handful of native species that will feed bees and butterflies from March until the first hard frosts. Native plants have evolved alongside our insects over thousands of years, so they offer exactly the pollen, nectar and leaf food that British wildlife is looking for. A pot of oxeye daisies on a city balcony is not a token gesture; it is a genuine pit stop on a foraging route. Small spaces, joined up across a street or an estate, add up to something far greater than the sum of their parts.

Choosing native wildflowers that suit containers

Not every wildflower tolerates life in a pot. The best candidates are compact, forgiving of occasional drying out, and happy in a limited root run. Perennials give you the best return, flowering year after year with very little fuss.

• Oxeye daisy — cheerful, long-flowering and a magnet for hoverflies and small beetles.
• Field scabious — soft mauve pincushions that bees adore well into late summer.
• Common knapweed — thistle-like and tough, a favourite of bumblebees and butterflies.
• Yarrow — feathery foliage, flat flower heads, and it shrugs off drought.
• Red campion — early colour for long-tongued bees, and it self-seeds politely.
• Birds-foot trefoil — the food plant of the common blue butterfly; wonderful in a trough.
• Wild marjoram — aromatic, late-flowering and covered in bees on a warm evening.
• Viper's bugloss — startling blue spires that seem to hum in midsummer.

Annuals such as cornflower, corn marigold and common poppy are brilliant gap-fillers, flowering within twelve weeks of sowing. Use a peat-free compost blended with about a fifth horticultural grit for drainage, and choose the largest pot you can accommodate — 30cm across is a sensible minimum, and a half-barrel is better still.

Spring: sowing, potting on and the first bees

March and April are the busiest months. Sow annuals thinly on the surface of moist compost and barely cover them, because most native seed needs light to germinate. Perennials are better started in modules and potted on once they have a few true leaves. Keep everything watered with rainwater if you can, and resist the urge to feed heavily — wildflowers want lean conditions, and rich compost gives you floppy leaves at the expense of flowers. By late April a queen bumblebee emerging from hibernation will find your first blooms, and that is one of the quiet pleasures of a small garden.

Summer: colour, water and the tricky art of doing less

From June to August, watering is the main task. Water in the early morning, soaking the pot thoroughly rather than little and often, and stand containers on saucers in the hottest spells. Deadhead annuals to keep them going, but leave a few to set seed for next year. Resist the temptation to tidy too neatly: seed heads, slightly scruffy stems and a few aphids are all part of the food web, and ladybirds will deal with the aphids if you leave them to it. Never use pesticides on a wildlife planting. A shallow dish of water with a few pebbles pushed in makes a safe drinking station for bees and hoverflies.

Autumn: collecting seed and planting for next year

September to November is the best window for planting perennials, while the soil is still warm and roots can establish before winter. It is also seed-collecting season. Snip dried flower heads into a paper bag, label them, and store somewhere cool and dry until spring. Cut back roughly half of your spent growth and leave the rest standing for the birds and overwintering insects. Skip yellow rattle in containers — it is a parasite of grasses and needs a grassy meadow to do its work. If you have a front garden or a patch of bare earth, autumn is also the moment to plant a native hedge of hawthorn, blackthorn or dog rose; these need ground and patience, and they will not thrive in a pot.

Winter: seedheads, structure and planning ahead

From December to February there is little to do beyond the essentials. Leave seedheads standing for goldfinches and other finches. Raise pots onto feet or bricks so they do not sit in standing water, and check drainage holes after heavy rain. A clipped pot of common ivy earns its place, flowering late and offering shelter, though it needs firm annual pruning. Otherwise, use the quiet months to plan: clean your pots, order seed, and sketch out where you might squeeze in one more container. Come March, you will be ready — and so, quietly, will the bees.