Low Sugar Strawberry Jam

It has taken me a long time to get sufficient strawberries on the plot to start to wonder what I could do with the excess. This year with a combination of another 30 strawberry plants and some bird protection I finally had too many strawberries. I froze some for use later in the year but also had enough to make a couple of kilos of jam.

I’m a big fan of lower sugar or what you might call fridge jams. These are bottled and stored in the normal way but once opened should be refrigerated and consumed in a couple of weeks. For that reason I use smaller jars, usually around 250g. If you grow your own or have access to a large supply of strawberries why not give it a go.

Ease – Medium

Time – 1 hour

5 a day – Whilst technically fruit, the amount of sugar in jam, even fridge jam means it doesn’t count


1 kg strawberries

500g preserving sugar with pectin

Juice of half a lemon


One large pan at least three times the size of the volume of strawberries you want to cook

6 227g jam jars and lids

Jam thermometer (not essential but it helps)

Funnel with a mouth small enough to fit in to the jars (not essentials but it helps)

Slotted spoon

Potato masher


Wax disks (optional)

Tongs (optional)

Sterilising Equipment

Check jars and lids well for signs of damage. Discard any that are damaged. Wash all of your equipment well in hot soapy water (unless using the dishwasher method). There are a few methods to sterilise your equipment and jam jars.

The first is to run it through a hot cycle on a dishwasher.

The second is to bring to a boil in a pan for 2 minutes and leave to dry upside down on a clean fresh teatowel.

The third is whilst jars are still warm from washing to heat it in an oven at 140C for 15-30 minutes, I use a boiling hot water bath to reduce the risk of uneven heating and do not use the fan oven.

The inside of the jars must be dry before you use them which is why I tend to use the oven method for jars.

Wax disk or not to wax disk

The purpose of wax disks is to prevent air getting to the top layer of jam which over time can cause spoilage and discolouration. It also means if you are hot bottling that no condensation will drop on to the surface of the jam which again can lead to spoilage. For acidic foods like chutney they help to stop the acid reaching the metal lids, causing damage and for preserves they were an absolute necessity when jam might have been stored with only paper or fabric lids. However if you are using proper metal lids for jam, especially if you water bath can the jam after bottling, they are less necessary. They do however still prevent discolouration of the top level of jam which can occur with long term storage.


Place a plate in to the freezer to allow you to test the jam later.

Sterilise your equipment

Remove any stalks from the strawberries. Cut any large berries in to half.

Add your strawberries to the pan and roughly mash half of them to a rough pulp with the potato masher.

Bring the strawberries gradually to a simmer, stirring occasionally.

Add the sugar. Any lumps of fruit will probably not break down further after this point.

Stir to dissolve the sugar and then bring to the boil. Be aware that jam at a rolling boil will increase significantly in volume, is hotter than boiling water and can cause serious burns so be careful at all times and do not leave it unattended especially if children or pets are present.

Skim any foam that appears off with your slotted spoon.

Boil hard for at least 5 minutes. After 5 minutes you can start to test the set of the jam. If you have a jam thermometer you are looking for the temperature to be 103c or higher. If you do not have a thermometer you will start to see a change in how the jam is boiling. To test the set remove the plate from the freezer and place a small amount of the jam on the plate, wait a little while for it to cool and draw your finger through it. If the jam parts with your finger and stays apart then it is done. If it floods back then keep boiling.

When your jam is ready then start to bottle it before it starts to cool. I use a ladle and funnel for ease but you can just use a sterilised spoon or ladle. I also jar in the waterbath that I sterlised the jars in as it stops the work surfaces getting sticky! Leave at least 1cm headspace between jam and the top of the jar and clear any residue jam from the mouth of the jar. If you are using wax disks gently lay shiny side down on the top of the jam. Screw lids on tightly.

You can store this in a cool dark place for up to 4 months. Once opened refrigerate and use within two weeks.

If you want a longer shelf life then clean out your jam pan and fill with boiling water, whilst the jars are still warm (with the lids on!) add them to the pan using tongs. Boil for 20 minutes to fully sterilise the jam. This jam will keep for up to a year.

Use your jam spread on buttered toast or fresh bread. A couple of spoonfuls on plain yogurt is also a lovely breakfast or quick dessert.

If you want to try something a little different, add a couple of spoons to vanilla ice-cream or top a meringue nest with some whipped cream or yogurt and a couple of spoons of the jam.

One Comment Add yours

  1. Sheree says:

    This is how I make most of my preserves

    Liked by 1 person

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