Introduction to Jam Making (Part 1) – Materials and Methods

(nb – some links go to Amazon, and I’d encourage you to seek out small independent retailers close to where you live instead. I am sharing these links merely to illustrate the items. Don’t be put off by the length of this list – it’s very detailed, and you may already have some of the things needed)


  • a heavy-bottomed stainless steel pot. We use a 5L pot from Ikea (the older version of this one), which we also use to cook in. This size works well for 1-2kg of fruit, but if you are planning on making more jam then a larger pot (8L or 10L) would be a useful thing to have. Don’t feel like you need to buy a pot specially though – use what you already have and see how you like it
  • a jam thermometer. We have this one and we like it because the pin (is that the right word?) is really long so you don’t burn your fingers while holding the thermometer. A word of warning, though – you need to hold the thermometer in your right hand to be able to read it so if you’re left-handed you may wish to look for a different kind. This kind of thermometer is also useful for other purposes – cheese-making, beer-making, sweetie-making, and all sorts of cooking adventures.
  • a jam funnel makes pouring your jam into your jars a lot easier. Here is an example of one but as long as it’s stainless steel and has a wide mouth then they’re all much of a muchness.
  • a wooden spoon or silicone spatula to stir with – use whatever you already have
  • jam jars with metal lids. Collect old jars and clean them – jam, pickles, olives, etc. all make excellent jars. Ask your neighbours and friends to save jars for you. Be sure to look for metal jars that ‘pop’ down when they’re sealed.
  • a way to sterilise your jars and lids. We like to use tablets (the same kind you use to sterilise baby equipment) such as these, but you can also sterilise jars by placing them in your oven on a high temperature for a while, and some dishwashers have sterilising settings.
  • something with which to label your jars. Sticky address labels or a permanent marker, whatever you like (and have at home – use that rather than buying new)


  • Fruit. Harvest your own and freeze until you’re ready to make jam, or buy fresh or frozen fruit. If you’re new to jam making a basic ‘fruits of the forest’ frozen bag of fruit works really well – you can get them at the supermarket and Lidl’s and Aldi’s are particularly inexpensive. 1kg of fruit is a good amount to start with, and should produce 6 small jars of jam.
  • Sugar. Ordinary granulated sugar. You need half the weight of the fruit in sugar, so for 1kg of fruit you need 500g of sugar (and maybe an extra table spoon or two if your jam does not reach 104.5C)
  • Lemon juice. This can be fresh or bottled. If fresh, one lemon should suffice for 1kg of fruit.
  • Optional: Apple Juice. Apples are high in pectin and can help your jam set. You can either cook an apple or two with your fruit (cored and peeled), or add in a glass of apple juice. 


This section is accompanied by the video above. In this example I am making plum jam but I would have made it the same way had it been ‘fruits of the forest’ or any other mixed or single fruit jam with the exception of strawberries. A note on heat: as you’ll see from the video we have an Aga, so I can’t tell you exact temperatures. Low/Medium/High is as precise as it gets, so please take that under consideration and adapt it for your own cooker.

Before you start sterilise your jars and lids. If your fruit is frozen, add it to your jam pot with a glass of water or apple juice and heat them on low heat until it defrosts. If you are using fresh fruit chop it into small chunks – quarter or halves. Small fruit like raspberries, currants or brambles can be left whole.

Once your fruit has defrosted (or your fresh fruit has warmed), add in your sugar and lemon juice. If you are using fresh lemon add in the juice of one lemon – if from a bottle then give it a good squirt (you can see how much I’m adding from the video). Stir to dissolve your sugar and bring to a boil. Once it boils turn down the heat and keep cooking the fruit until soft. Your goal here is not to cook it as quickly as you can but to cook it slowly over a period of time – aim for Medium-Low heat. This way your juice cooks down more slowly and your flavour will be more intense, and you don’t have to stir as often as it is less likely to stick to the bottom and burn. Keep an eye on that, though – don’t let it burn as you’d be able to taste this in your jam. Once your fruit is soft and your juice has reduced down – you’re aiming for mostly fruit with a bit of juice, like a rich tomato sauce – it is time to heat your jam quickly. Turn up the heat and get your thermometer – and stir frequently. Once your jam is at 104.5C keep boiling it for a couple of minutes (stirring continuously), then take it off the heat and decant it into your jars – add the lids as quickly as you can. Fill your jars to just under the top – there is usually a bit where the jar narrows, so fill to there. Be careful, though, as the jam is very hot and so will your jars be. Tighten the lids as best as you can. Leave your jars to cool down and, once cool, tighten you lids again and label your jars, both with content and the date you’ve made it. If you end up with any half-full jars designate them ‘fridge jam’ for immediate consumption!

If your jam does not reach 104.5C there are a few of things that can help.
1. Add in some apple juice – because it is high in pectin this can help your jam set.
2. Add more sugar – a couple of tablespoons. This can help raise the temperature.
3. Cook the jam for a bit longer on high heat until more juice evaporates. Be sure to keep stirring so it doesn’t burn.

If all else fails and it gets stuck at 102C or 103C  I tend to just decant it anyway and hope for the best – and if it doesn’t set and I end up with runnier jam I’ll use it on porridge or ice cream or pancakes.

A note on looks, smells, and feels: pay attention to what your jam looks, feels and smells like while you’re cooking it. The video gives you a bit of an indication of the different ways it looks but obviously can’t transmit smell and feel to you. At the beginning when you’re just starting to heat up your jam it’ll be like juice with solid fruit in it, and there’s often frothy foam while you’re heating it to boiling. Once it reaches that point it’ll really start to smell like fruit – so delicious – and it’s usually at this point that any flatmates come running to see what’s smelling so nice. As the juice cooks down you’ll notice that the fruit is getting softer and the individual chunks tend to turn into a kind of mush, and the juice thickens. The whole mixture will likely darken, too. The jam is ready for it’s final ‘rush to 104.5C’ adventure when there is practically no juice left and everything just sort of looks like one mushy thick soup – much like tomato sauce. As you practice your jam making you’ll notice these changes and points more easily but try to to pay attention to them from the beginning as they’ll guide you through the process far better than a literal description of ‘do this thing for x minutes’. 

The things you really need to remember about making jam is double the weight of fruit for the amount of sugar, and bring to boil, cook slow, boil quickly to 104.5C. That’s your basic instructions, and internalising those goes a long way towards making you feel like you know what you’re doing!

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