Start with the Site, Not the Shopping List

Most cottage borders fail for want of light rather than skill. Before you buy a single plant, watch your chosen spot for a week and note how many hours of direct sun it receives. Classic cottage planting wants six hours or more; if you are working with a shady mews courtyard, you can still have a lovely border, but you will be choosing from a different palette entirely — hellebores, pulmonaria and hardy geraniums rather than lavender and penstemon.

Next, mark out the shape. A length of hosepipe or garden twine is ideal, because it lets you curve the edge rather than rule a straight line. In a compact mews plot, a border of 90cm to 1.2m deep is usually plenty. Any wider and you cannot reach the back without treading on the plants, which is the single most common mistake in small gardens.

Finally, check your soil. Fork over the top 20cm and see what you have. If it is heavy clay, add well-rotted manure or garden compost in autumn and let the worms do the rest over winter. If it drains in minutes, work in the same compost plus a little leafmould. Cottage planting is generous and hungry, so it pays to feed the ground before you feed the plants.

Build a Backbone Before You Go Shopping

A border made only of perennials looks wonderful in July and like a muddy car park in February. Give it structure first. Aim for roughly a quarter of the border to be shrubs or strong architectural plants, then let everything else billow around them.

• For small spaces: shrub roses such as 'Gertrude Jekyll', choisya, philadelphus 'Manteau d'Hermine' or a compact hydrangea.
• For scent near a door: a climbing rose or honeysuckle trained up a wall, which costs you almost no ground space.
• For repeat flowering: lavender and nepeta at the front edge, both of which cope well with the sheltered warmth of a mews courtyard.

Place these first, on paper and then in the ground, and resist the urge to dot them about singly. Cottage borders work because plants are repeated — one shrub here, one shrub there reads as random, while three of the same thing reads as deliberate.

Layer Perennials for Colour Across the Seasons

This is where the border earns its keep. Think in three waves rather than one long list.

• Early: hellebores, pulmonaria, epimedium and early hardy geraniums to carry you from February to April.
• High summer: aquilegia, salvia, penstemon, achillea, verbena and hardy geraniums again — they flower for months if you shear them back after the first flush.
• Late: rudbeckia, helenium, asters and sedum, which look their best just as the light softens in September.

Plant in drifts of three or five, and repeat the same plant in two or three places along the border. That repetition is what stitches a long, narrow border together and stops it looking like a plant collection.

Fill the Gaps with Annuals and Biennials

Perennials take a season or two to settle, and they always leave gaps in their first year. Annuals are the cheapest way to paper over the cracks while you wait.

Sow nigella, calendula and cosmos directly in May where they are to flower — they resent transplanting. Sweet peas go in as seedlings against any vertical surface and will scramble up a simple frame. Wallflowers and honesty are biennials, sown one summer to flower the next, and honesty earns its place twice over when the seedheads turn silver in autumn.

Let a few of these self-seed. A cottage border that gently edits itself, with foxgloves appearing where you did not plant them, is far more charming than one that is rigidly controlled.

Bulbs: The Secret to a Border That Is Never Bare

Bulbs are what separate a good border from a great one, and they cost very little for the effect. The trick is to plant them underneath the perennials rather than in a separate strip.

• Snowdrops and crocus at the very front for January and February.
• Narcissi in generous handfuls, planted 10cm deep in September, to bridge spring and early summer.
• Alliums for May and June — their seedheads stay structural well into autumn.
• Tulips for the weeks in between, planted fresh each November if you want them to stay reliable.

Because the perennials are still dormant when most of these flower, the bulbs get their light and then quietly disappear as the foliage around them fills out. In a mews courtyard, this layering also means you can pack a great deal of seasonal interest into a very small footprint.

Put It on Paper, Then Plant It

Sketch your plan roughly to scale, pencil in the shrubs, then mark drifts of perennials and note where the bulbs will sit beneath. Buy in autumn or early spring for the best choice, and plant on a damp, overcast day if you can arrange one.

Space perennials roughly 30–45cm apart, closer if you want a filled look in year one, and mulch the whole border with 5cm of compost. Water thoroughly for the first summer, then let the plants find their own way. By the second year you will have a border that gives you something to look at in every month of the year — which is the whole point of a cottage garden.