Making Cold-Infused Herbal Iced Teas at Home

Why Cold Water Makes a Better Summer Brew

Hot water is a blunt instrument. Pour it over fresh mint and you get a dark, slightly stewed liquid within minutes, because heat drags out tannins, chlorophyll and the bitter compounds locked inside the leaf. Cold water works far more politely. Left in the fridge overnight, it draws out the fragrant oils — menthol in mint, citral in lemon verbena, the soft apple notes in chamomile — while leaving most of the astringency behind. The result is a pale, clean infusion that tastes like the plant smells on a warm afternoon.

There is a practical bonus that matters more than anything else in July. A cold infusion is never harsh, so it needs no sugar, no honey and no lemonade to soften it. You are drinking water that has borrowed a flavour, not a syrup. That is why a jug of it disappears so quickly on a hot day, and why the habit is so easy to keep once you have tried it.

Three Herbs That Earn Their Place

Almost any soft herb can be cold-infused, but these three are the ones I return to every summer, and all three grow happily in a British garden or on a sunny windowsill.

• Mint. The workhorse. Spearmint is softer and sweeter, peppermint sharper and more medicinal. Both spread aggressively, so keep them in pots unless you want a mint lawn. Black-stemmed peppermint is worth seeking out for its colour alone.
• Lemon verbena. My favourite of the lot, and the one people always ask about. Crush a single leaf and the scent is pure lemon sherbet. It is a tender shrub, so grow it in a large pot and bring it indoors before the first frost — overwintered plants become generous bushes within two or three years.
• Chamomile. German chamomile is an easy annual from seed, and the flowers are what you want, not the feathery leaves. It gives a gentle, honeyed infusion, but it turns bitter after about twelve hours, so it is the one to strain promptly.

Beyond these, lemon balm, fennel fronds, basil, rose-scented geranium leaves and even a few raspberry leaves all work well. Treat the list as a starting point rather than a rule.

The Basic Method

The proportions are forgiving. As a reliable starting point, use roughly 15g of fresh herbs — a generous handful — to 1 litre of cold water. Dried herbs are about three times stronger by weight, so a tablespoon per litre is plenty.

• Pick your herbs in the morning, before the sun has had time to draw the oils out of the leaves.
• Rinse them, then bruise the leaves lightly between your fingers or with the back of a spoon. You are not trying to shred them, just to open the cell walls so the flavour can escape.
• Drop them into a clean jug or a large jar and cover with cold water. Filtered water makes a noticeable difference if your tap water is heavily chlorinated.
• Cover and refrigerate for six to twelve hours, or overnight. Leave it on the counter only if you plan to drink it within four hours.
• Strain through a fine sieve, pressing the leaves gently. Taste as you go — if it is too soft, add a few fresh leaves and give it another hour.

One caution worth repeating: do not muddle the herbs to a pulp. Bruised, torn leaves release bitterness much faster than lightly crushed ones.

Combinations Worth Brewing

Once the basic method is in your hands, the interesting part begins. These three blends have never failed me.

• Mint and cucumber. A handful of spearmint, four or five thin cucumber slices and a litre of water. Cooling to the point of being almost savoury.
• Lemon verbena and green tea. Cold-brew a teaspoon of loose green tea alongside the verbena leaves. The tea brings a grassy backbone; the verbena lifts it. Strain at eight hours to avoid the tea turning bitter.
• Chamomile and lemon balm. Two tablespoons of chamomile flowers and a good handful of lemon balm. Soft, floral and excellent before bed. Strain at six hours.

A slice of lemon or lime, a sprig of thyme, a few crushed cardamom pods — all are welcome additions, though I would add citrus at serving time rather than during the steep, as the pith turns the whole jug bitter overnight.

Growing Your Own Supply

You need far less space than you might think. A single supermarket pot of mint, split into three and replanted into a 30cm container, will keep you in leaves from May to October if you water it daily and pinch out the flowering tips. Lemon verbena wants the sunniest spot you have and a pot at least 25cm across; feed it fortnightly through summer and it will reward you with armfuls of leaf. Chamomile sows easily in spring — scatter the seed on the surface of damp compost, since it needs light to germinate, and you will have flowers by July.

Pick regularly rather than sparingly. Herbs that are cut hard bush out and stay productive; herbs left alone go woody and flower, and flowering mint loses much of its flavour.

Serving, Storing and Small Adjustments

Keep the strained tea in the fridge in a covered jug and drink it within three days — beyond that, the flavour flattens and any citrus turns dull. Serve it over plenty of ice in a sturdy glass, with a fresh sprig on top; the aroma of an uncrushed leaf does half the work of the first sip.

Freeze leftover infusion in an ice cube tray with a small mint leaf in each cube, and you have both a garnish and a way to chill a second glass without diluting it. If you want a little sparkle, top with soda water rather than lemonade. And if a batch tastes weak, resist the urge to add sugar — simply steep the next one longer, or use more herb. That is the whole pleasure of cold infusion: it asks for patience instead of sweetness, and it gives it back in full.