Homemade Strawberry Jam
Jam-making day was an event. A glut of strawberries — too ripe to keep, too good to waste — the biggest pot in the house, and every jar in the parish washed and waiting on the windowsill. By evening the shelf glowed red and the whole kitchen smelled like summer.
Granny never owned a thermometer. She used the wrinkle test: a saucer in the freezer, a drop of jam, a push with the finger — if it wrinkles, it's set. It's still the most reliable method we know, and we've written it into the recipe below exactly as she did it.
One honest note: strawberries are low in pectin, so use jam sugar (sugar with pectin added) or boost regular sugar with extra lemon juice. Spread it thick on warm scones or soda bread — that's what it's for.
Homemade Strawberry Jam
Just fruit, sugar and lemon — with the cold-saucer wrinkle test for a perfect soft set.
Ingredients
- 1000 g ripe strawberries, hulled
- 750 g jam sugar (sugar with pectin)
- Juice of 1 lemon
- Small knob of butter (optional)
Use ordinary granulated sugar and the juice of 2 lemons instead of 1 — the extra acid helps the set. Expect a softer jam.
Method
- Prepare. Put 2–3 saucers in the freezer. Sterilise 4 jars (hot soapy wash, rinse, 15 minutes in a 140°C oven); simmer the lids.
- Macerate. Layer the strawberries and sugar in a wide, heavy pan with the lemon juice. Leave 30 minutes (or overnight, chilled) until glossy and juicy.
- Dissolve, then boil. Warm gently, stirring, until every grain of sugar has dissolved. Then boil hard, without stirring, 8–12 minutes.
- Wrinkle test. Off the heat, drop a little jam on a frozen saucer, wait 30 seconds and push with a finger. Wrinkles? Done. Runs? Boil 2 minutes more and test again.
- Jar. Stir in the butter to clear the scum, rest 10 minutes so the fruit won't float, then ladle into hot jars and seal at once.
Take the pan OFF the heat while you test — two extra minutes of boiling while you fiddle with saucers is how jam turns to toffee.
Tips for a perfect set
Wide pan, hard boil
A wide pan evaporates faster, so the jam reaches setting point before the fruit stews to mush.
Trust the wrinkle
Saucer from the freezer, drop of jam, 30 seconds, push. Wrinkle = set. More reliable than any clock.
Hot jam, hot jars
Sterilised, oven-hot jars sealed immediately are what make jam keep for a year.
Questions, answered
Why won't my strawberry jam set?
Strawberries are naturally low in pectin. Use jam sugar, or add the juice of two lemons — and make sure you boil hard enough. A gentle simmer never reaches setting point (105°C). Trust the wrinkle test over the clock.
How do I sterilise jars?
Wash in hot soapy water, rinse, then dry in a 140°C oven for 15 minutes. Simmer the lids. Always ladle hot jam into hot jars — cold glass can crack.
How long does homemade jam keep?
Properly sealed in sterilised jars, 12 months in a cool dark cupboard. Once opened, fridge it and use within a month.