For a fortnight each May, the hedgerows along every country lane turn frothy with creamy-white blossom, and the air smells of muscat and honey. Elderflower cordial is the taste of that fortnight caught in a bottle — a few pounds of sugar and a basket of blossom, and you have summer drinks sorted until the sloes come in.

An Heirloom in the Hedgerow

Elder has followed British dwellings for centuries. It was once planted by the back door as an apothecary tree, credited with keeping misfortune at bay, and every part of it has been used for something: the bark for dye, the berries for wine and rob, the flowers for fritters, vinegar and cordial. Making your own is less a recipe than a small act of continuity. Nothing about it is difficult, but it is gloriously time-sensitive. Miss the fortnight and you wait another year.

Finding Your Blossom

Elder (sambucus nigra) grows almost everywhere — hedge banks, railway cuttings, the edges of churchyards and car parks. Look for a shrub or small tree with corky, fissured bark and opposite, pinnate leaves: five to seven oval leaflets with serrated edges. Bruise a leaf and you will get a distinctly green, slightly rank smell, which is useful confirmation.

The flowers are flat-topped plates of tiny, star-shaped, creamy-white blooms, held upright and heavy with pollen. They appear from late May into June, earlier in the south and west, later in Scotland. A few things are worth checking before you pick:

• Colour: you want fresh cream, not white and tight, and certainly not beige or browned.
• Scent: sweet, floral, slightly muscat. If it smells sour or catty, it is past its best.
• Setting: favour clean hedgerows well away from busy roads, and avoid anything at nose height along a well-used dog-walking path.
• Permission: on private land, ask. On verges and public footpaths, take only what you need and leave plenty behind — those flowers become the berries the blackbirds rely on in autumn.

Picking Well: Timing and Manners

Choose a dry morning. Rain washes away the pollen and the fragrance, and damp heads go mouldy in the bowl. Wait until the dew has burned off but the day has not grown hot — the scent is at its strongest then, and the insects are gentler.

Take a basket or a shallow cardboard box rather than a carrier bag, which crushes and sweats your haul. Snip whole heads with a short length of stalk; you will be straining everything out later anyway. A gentle shake dislodges most of the residents, though a few stray aphids or beetles are not a problem — they will be caught in the muslin. Twenty to thirty generous heads will make a good batch, about two litres of finished cordial.

The Recipe

This is the version I come back to year after year, and it scales easily.

• 20–30 elderflower heads, freshly picked
• 1.5kg granulated sugar
• 1.5 litres water
• 2 unwaxed lemons, zest pared in strips and juiced
• 30–50g citric acid (available from chemists and home-brew shops)

Warm the sugar and water in a large pan over a low heat, stirring until the sugar has completely dissolved. Do not let it boil hard. Take it off the heat, add the lemon zest and juice, and let it cool to lukewarm — pouring it boiling over the flowers cooks out the very perfume you are trying to capture.

Tip the flower heads into a large bowl or a thoroughly cleaned bucket, pour over the syrup, then stir in the citric acid. Cover with a clean cloth and leave somewhere cool for twenty-four hours, or up to forty-eight if you want a fuller, more sherbety cordial. Stir twice a day. Longer than two days and it starts to turn dull and slightly bitter.

Steeping, Straining and Bottling

Line a sieve with a double layer of muslin or a clean tea towel and set it over a large jug or bowl. Ladle in the steeped liquid and let it drip through — this takes a while, so be patient. Once it has mostly drained, gather the cloth and squeeze gently, but do not wring it hard, or you will pull out bitterness and cloud the syrup.

Pour into sterilised glass bottles, or plastic bottles if you plan to freeze. Fill to within a couple of centimetres of the top, seal, and label with the date. In the fridge it keeps for about a month. Beyond that, decant into plastic bottles with a little headroom and freeze — it thaws in an hour on the counter and keeps a year or more.

Drinking and Varying

Dilute roughly one part cordial to five parts sparkling water or chilled still water, over plenty of ice, with a sprig of mint and a slice of lemon. It is equally good lengthened with gin, splashed into a glass of dry white or prosecco, spooned over strawberries, or trickled over vanilla ice cream. A spoonful stirred into a gooseberry fool is a fine thing indeed.

Once you have the basic method, the variations are endless: a handful of mint leaves or a thumb of bruised ginger in the steep, a little orange zest alongside the lemon, or a few heads of elderflower added to a pan of stewing gooseberries. Two points of good practice: use citric acid if you possibly can, as it both sharpens the flavour and slows the wild yeasts that will otherwise send your bottles fizzy; and keep it cold. A cordial that has fermented is not spoiled, but it is no longer a cordial — drink it soon, and enjoy it for what it is.