A cottage border is the most generous thing you can make in a garden. Fill it once with the right plants and it will come back stronger every year, feeding the bees, scenting the evening air and giving you something to cut for the kitchen table. The trick is not to plant a hundred different things and hope for the best, but to build in layers: structure at the back, perennials through the middle, self-seeders to fill the gaps, and bulbs and ferns for the seasons the flowers are resting.

Get the Site and Soil Right First

Almost every perennial in a classic British border wants the same thing: sun for at least six hours a day and soil that holds moisture without sitting wet. If your border faces north or sits under a mature tree, don't fight it — plan a fern-and-foliage border instead, which can be every bit as lovely.

• Make the border generous. A depth of 1.2 to 1.5 metres is what allows plants to be layered properly. Narrow strips of 60cm always look thin and apologetic.
• Fork the ground over to a spade's depth and dig in two buckets of well-rotted compost or leaf mould per square metre. On heavy clay, add a bucket of horticultural grit at the same time.
• Rake the surface to a gentle crown so rain runs off the plants rather than pooling at their crowns.
• Mark a smooth curve with sand or a length of hosepipe before you cut the edge. A clean, flowing line matters more to the finished look than any individual plant.

Put in a Backbone of Shrubs

Perennials die back, so roughly a third of the border should be shrubs that hold their shape all year. Choose a handful, not a crowd. A repeat-flowering Rosa such as 'Gertrude Jekyll' or 'Lady of Shalott' gives scent and cut flowers. Hydrangea arborescens 'Annabelle' carries huge white heads from July. Philadelphus 'Belle Étoile' fills June with orange-blossom scent, and Viburnum bodnantense 'Dawn' flowers on bare stems from November. Tuck in one or two evergreens — a clipped box or a low Pittosporum — for winter bones.

Space shrubs at their mature spread. It feels extravagant to leave gaps in the first year, but perennials will grow into them within two seasons. Plant in October or March, firm them in well and mulch with bark or compost to 8cm, keeping it clear of the stems.

Layer In the Herbaceous Perennials

Now the colour. Plant in groups of three or five rather than ones and twos, and repeat the same plants at intervals along the border so the eye travels. Work in height bands: low growers to 40cm at the front, mid-height plants at 60 to 90cm, and tall things at the back.

• Front: Geranium 'Rozanne' for months of blue, Alchemilla mollis for chartreuse froth, Nepeta 'Six Hills Giant' to spill over the edge.
• Middle: Salvia nemorosa 'Caradonna' for spires of deep violet, Achillea 'Moonshine' for flat yellow plates, Penstemon 'Andenken an Friedrich Hahn' for late colour.
• Back: Helenium 'Moerheim Beauty', Echinacea purpurea and the tall asters that carry the border into October.

Aim for succession rather than a single glorious fortnight. Geraniums take you through June, salvia and achillea bridge July, helenium and echinacea carry August, and asters finish the job.

Use Ferns for Shade and Quiet Texture

Ferns earn their place even in a sunny border, softening the base of shrubs and filling the shadier end where little else thrives. Dryopteris erythrosora unfurls coppery new fronds in spring, Polystichum setiferum is evergreen and tolerant of dry shade, and the hart's tongue fern, Asplenium scolopendrium, looks superb against a wall or path edge. In damp soil, Matteuccia struthiopteris will run happily once established.

Give them leaf mould, water them through their first summer and never cut the old fronds until the new ones are up. There's a pleasant symmetry here with the ferns many of us grow indoors: a Boston fern in a cool bathroom wants much the same treatment — indirect light, steady moisture, and a spell outside in a shady corner over summer. Bring tender ferns in before the first frost, and check the compost for slugs and vine weevil grubs as you do.

Self-Seeders and Bulbs for a Spring Return

The magic of a cottage border is that it partly plants itself. Leave a few Aquilegia, foxgloves, Verbena bonariensis, nigella and annual poppies to scatter their seed, and you'll have free plants in unexpected places for years. Edit the seedlings in April, keeping the strongest and moving any that have landed somewhere silly. Leave seed heads standing over winter — they look beautiful in frost and feed the goldfinches.

Underneath everything, plant bulbs in September and November at three times their own depth: Narcissus 'Thalia', crocus, snowdrops, and Allium hollandicum 'Purple Sensation' for globe-shaped flowers in late May. They'll push up through the perennials just as the border is waking.

Keeping It Looking Well Through the Year

• March: cut back last year's stems, fork the surface lightly and scatter a balanced fertiliser.
• Late May: cut some tall perennials back by a third — the Chelsea chop — to delay flowering and stop the border flopping. Stake the rest with hazel pea sticks while they're still short.
• June to August: deadhead regularly and water deeply in dry spells rather than little and often.
• Autumn: lift and divide congested clumps every three years, replanting the outer, young pieces.

Do that, and you'll have a border that returns each spring with less work and more colour every season — the quiet, generous heart of a British cottage garden.