Making Jam from Seasonal British Fruit

Small Batches, Big Flavour

There is a particular pleasure in a shelf of homemade jam: rows of glass catching the light, each jar holding a few weeks of a British summer. Making jam at home is not about thrift alone, although it certainly helps when the allotment produces more courgettes than anyone can eat. It is about catching fruit at its peak, when flavour is at its most intense, and preserving that moment in a way no supermarket jar can match.

Working in small batches is the secret. A pan holding two or three kilograms of fruit is manageable on a domestic hob, sets quickly, and keeps its bright, fresh taste. Large batches take longer to reach setting point, which cooks the colour and flavour out of delicate fruit. Aim for four to six jars at a time and you will have far more success.

What to Pick, and When

The British fruit calendar is generous if you know where to look. Rhubarb arrives first, from late March into May, and makes a sharp, glowing pink jam when paired with a little ginger. Strawberries follow in June and early July, then raspberries, gooseberries and blackcurrants. Cherries and apricots appear in July, plums and greengages in August, and by late summer the hedgerows offer blackberries, elderberries and sloes.

• High-pectin fruit — blackcurrants, gooseberries, damsons, cooking apples and plums — sets easily with ordinary sugar.
• Low-pectin fruit — strawberries, cherries, raspberries and pears — needs help from lemon juice or a preserving sugar with added pectin.
• Windfalls and gluts are perfect. Bruised fruit should be trimmed, not discarded; it often carries the deepest flavour.

Pick in the cool of the morning where you can. Fruit warm from the midday sun may already be softening, and slightly underripe fruit contains more pectin than fully ripe fruit — a mix of the two gives the best set.

The Kit, and Why It Matters

You do not need much, but what you use matters. A wide, heavy-based preserving pan allows rapid evaporation, which is what setting is really about. A long-handled wooden spoon keeps your hands away from spitting syrup. A jam thermometer takes the guesswork out of the setting point, though the saucer test works just as well.

Jars must be clean and hot. Wash them in hot soapy water, rinse well, then place them upside down in an oven at 140°C for fifteen minutes. Lids can be boiled for ten minutes and left to dry on a clean tea towel. Never pot jam into cold jars — the thermal shock can crack the glass, and a warm jar helps form a proper vacuum seal.

A Reliable Method

Weigh your prepared fruit, then match it with sugar. For high-pectin fruit use 750g sugar per kilogram of fruit; for low-pectin fruit use 1kg sugar per kilogram and add the juice of one lemon per kilo.

• Layer the fruit and sugar in a bowl, cover, and leave for several hours or overnight. The sugar draws out the juice, so the fruit keeps its shape and colour.
• Tip everything into the pan and warm gently, stirring until every grain of sugar has dissolved. Feel the base of the pan with the spoon; any grit means keep stirring.
• Bring to a rolling boil — a boil that cannot be stirred down — and hold it there. Strawberries may set in four minutes; plums and damsons can take fifteen.
• Test for set by dropping a teaspoon onto a chilled saucer. Let it cool, then push it with your finger. If it wrinkles, it is ready.

Setting Point and Potting Up

If you use a thermometer, setting point is roughly 105°C at sea level. Remember that jam continues to thicken as it cools, so a slightly loose set is better than a stiff one. Over-boiled jam turns dark, tastes caramelised and can set like glue.

Skim off any scum with a slotted spoon, then let the pan stand for five minutes. This brief pause lets the fruit settle so it does not all float to the top of the jar. Ladle through a wide funnel, filling to within a few millimetres of the rim, and seal immediately. Label with the fruit and the date — a small detail that pays off in January, when you cannot remember whether that jar is plum or damson.

Waste Less, Share More

Sustainable jam making sits neatly alongside a lower-waste kitchen. Reuse jars and lids year after year, sterilising them thoroughly each time. Freeze surplus fruit in bags as you pick it, then make jam in November when the kitchen is cool and the hob is on anyway. Fruit too soft for jam can become a fruit leather or a cordial instead.

Swap jars with neighbours who grow something you do not, and take a few to the allotment committee or the school fair. A jar of jam is a small, generous thing, and it carries the taste of a particular week of a particular summer. That is something no supermarket shelf can offer.