There is a moment in early summer — usually the last week of May through to mid-June, depending on where you are in the country — when the hedgerows turn frothy with creamy-white blossom. Elder (Sambucus nigra) grows almost everywhere in Britain: along field edges, railway embankments, allotment boundaries, churchyard walls and country lanes. If you have never made elderflower cordial, this is the year to begin. It takes one afternoon, costs very little, and bottles the scent of early summer in a way no shop-bought version manages.

The finished cordial is sharp with lemon, heady with muscat, and sweet enough that a splash goes a long way. Here is how to make it properly.

When and Where to Pick Elderflowers

Elderflowers are at their finest on a dry, sunny morning, after a day or two of settled weather. Rain washes away the pollen, and pollen is where much of the fragrance lives. A few rules of the hedgerow will keep you, and the wildlife, happy:

• Pick from hedgerows well away from busy roads, where spray and exhaust settle on the blossoms.
• Choose heads where nearly every flower is open, with a fresh creamy colour. Avoid brown, shrivelled or dropping blooms, which smell sour.
• Leave plenty behind. Those flowers become elderberries in September, and the birds need them more than we do.
• Never pick from a plant you cannot positively identify. Elder has opposite, pinnate leaves with serrated leaflets, a shrubby, often untidy habit, and a distinctly muscat scent when a leaf is crushed. If in any doubt, walk on.

Carry a basket or a roomy bag rather than a plastic tub — bruised flowers brown off quickly. Around twenty-five large heads will make two litres of cordial, which is plenty for a household.

What You Will Need

• 25 large elderflower heads
• 1.5kg granulated sugar
• 1.5 litres water
• 2 unwaxed lemons
• 50g citric acid
• A large pan, a colander, a double layer of muslin, and sterilised bottles or jars

Citric acid is the one ingredient people forget. It is sold in pharmacists, homebrew shops and the baking aisles of larger supermarkets, and it does two jobs: it sharpens the flavour and, crucially, it preserves the cordial. Lemon juice alone will not do the same work. If you cannot find any, make the cordial anyway, but keep it in the fridge and use it within a fortnight.

The Steeping

Warm the sugar and water together gently until the sugar dissolves, then bring to a bare simmer for a minute and take the pan off the heat. Let it cool for ten minutes. Pouring truly boiling syrup over the flowers cooks them and flattens the perfume.

While it cools, shake each elderflower head over the sink to dislodge insects — earwigs and ladybirds are part of the deal — and pick off as much of the thick green stalk as you reasonably can, as it turns bitter. Try not to wash the heads, or you will rinse away the pollen that carries so much of the flavour.

Pare the zest from the lemons in wide strips, avoiding the white pith, then halve and juice them. Add the zest, juice, flowers and citric acid to the cooled syrup, stir well, cover with a lid or a clean tea towel, and leave in a cool place for twenty-four hours. Forty-eight is the absolute limit; beyond that the cordial turns vegetal and green, and there is a real chance it will start to ferment.

Straining, Bottling and Keeping

Line a colander with a double layer of muslin and set it over a large jug or bowl. Ladle in the mixture, flowers and all, then let it drip undisturbed for an hour or two. Resist the urge to squeeze the muslin — it clouds the cordial and pushes through bitterness. Compost the spent flowers.

Funnel the cordial into sterilised bottles. Swing-top bottles look handsome, but screw-cap bottles are easier to fill and less prone to leaking. Keep the cordial in the fridge, where it will hold for four to six weeks; without citric acid, treat two weeks as the limit. For longer storage, decant into plastic bottles, leaving a couple of inches of headspace, and freeze. Ice cube trays are handy for single servings.

One word of caution: if you are tempted to try elderflower "champagne", remember it is a live ferment. Unless you are confident about bottling pressure, stick to cordial — it will not redecorate your kitchen ceiling.

Drinking and Using Your Cordial

Dilute to taste — roughly one part cordial to five parts water or sparkling water, poured over plenty of ice with a sprig of mint and a slice of lemon. It also lifts a gin and tonic, adds a floral note to a glass of something fizzy, and makes a fine long drink with soda and cucumber.

In the kitchen, drizzle it over poached rhubarb, gooseberries or apricots, use it to sweeten whipped cream, brush it onto a lemon or yogurt cake while still warm, or loosen it into a syrup for sorbet. A spoonful stirred through natural yoghurt with toasted oats is as good a breakfast as June offers.

The season is short — often only three weeks in any one place — so pick twice, a fortnight apart, and make two batches while the blossom is at its best. Label each bottle with the date, store it somewhere cool and dark, and you will be pouring early summer into a glass long after the hedgerows have gone over to berries.