This easy recipe is my favourite way to preserve watermelons with a simple canning process and sweet and lemony brine. Perfect recipe if you have a lot of watermelons and want to preserve them for later.

Once made, these canned watermelons will last a few months and can be eaten in exactly the same way as fresh ones (when made in sweet brine) or add to salads or used as a side dish with cheese, pate or meats (when made in the original sweet & salty brine).

Why make this recipe?

Quick & easy to make
No need to can or boil the jars
Small batch recipe

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How are the canned watermelons going to taste like?

The watermelons will take on a slight taste of the brine that we are using to preserve them. The brine has a sweet, salty and sharp lemony flavour.

The aspirin doesn’t taste of anything, so won’t make a difference to the flavour. If you want to change the flavour, you can add more sugar or less salt, but both are important for preserving watermelons.

The citric acid is basically concentrated lemon, which is what gives the brine it’s sharp flavour.

Sweet brine – increase the amount of sugar by 100% and decrease the amount of salt by 50%

Sweet & Salty – keep the recipe as it is

What makes this recipe work

Adding aspirin, salt and citric acid helps to preserve the watermelons for longer. Sugar has preserving qualities as well, but it’s mainly there for flavour.

My top tips on making this recipe successfully the first time round

Get everything ready first, starting with sterilising the jam jars and lids. Make sure that the brine is quickly stirred just before you pour it into the jars in case, there is any ingredient sedimentation.

Pro tip

Make sure that the water comes up very close to the top of the jar. It shouldn’t touch the lid, but be about 1 cm down from it.

What type of watermelon to use

It’s best to use firms medium watermelons that are just about ripened. It’s difficult to use over rippened watermelons as they are prone to disintegration.

Preserving process

The beauty of this recipe is that you don’t need to use water bath to preserve the watermelons. The hot water, citric acid and aspirin will make sure that the watermelons will keep for few months.

I’ve used this simple brine preserving method in this recipe, but if you want to you could preserve the watermelon jars further by boiling them in a hot water bath (or pressure cooker) and extend their shelf life to 1-2 years.

Sterilising jars

No matter what method you use, always make sure that your jars are clean and sterilised. This prevents bacteria from developing inside your canned watermelons.

To sterilise your jars (and lids) wash them either in a dishwasher on a very hot cycle or wash them by hand and then put in the oven on 100 C (210 F) for about 10 minutes. This is enough to remove any unwanted bacteria and sterilise your glass jars.

Any type of jam jar or traditional mason jar is suitable for canning watermelons, but sometimes it’s easier to use a bigger jar and keep the vatermelon chunks large. Having a bigger jar allows you to lay the watermelon pieces exactly how you want them.

If I’m making gifts for my friends and family, I’d often choose small jar jars and decorate them with pretty labels, ribbons and fabric covers.

Allergies & dietary requirements

This recipe is fairly straightforward and is vegan, vegetarian and gluten free. Some people can be, however alergic to aspirin, so make sure that you check before serving the canned watermelons (or giving a homemade jam jar as a gift).

Canned watermelons ingredients

watermelon
water
sugar
citric acid
aspirin
salt

How to make canned watermelons recipe

Wash and scrub the watermelon first to remove any dirt. We will be using the whole watermelon, so make sure it’s clean. Don’t use any cleaning products to wash the watermelon, just water and a clean cloth.

Cut the watermelon into medium size triangles approximately 1,5 cm (thumb size) in thickness. You don’t want to make the watermelons too thin otherwise they might not hold their shape when they are packed in the jar.

Wash the jam jars and lids and sterilise them by placing them on a clean baking tray in oven for 10 minutes on about 100 C (210 F).

Layer the pieces of watermelon in the jam jars always slightly overlapping with the next layer (like you see on a brick wall).

Bring to a boil 1,5 litres of water (about 6 full cups plus 1/3 cup) either in an electrical kettle or a large saucepan.

Measure out the sugar, salt, citric acid and aspirin and add them to the boiling water. Mix until dissolved.

Give the mixture another stir before pouring it carefully into your jam jars. Split it evenly between the jars first. If you have any gaps, boil more water and top it up (no need to add more preserving ingredients).

Immediately screw on the jam jar lids (use kitchen towels to hold the jars).

Leave the canned watermelons on a work counter until they cool down completely, before storing them somewhere cold and out of direct sunlight.

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How else you can make this recipe?

You can make the brine sweeter by increasing the amount of sugar and reducing the amount of salt. This will make the watermelons sweeter and taste more like fresh ones.

How to serve canned watermelons

Canned watermelons are perfect to use for fruit or vegetable salads, as a side fruit to serve with pate or cheese.

Depending on how you make it, you can add less salt and use the watermelons like a fresh watermelons for making smoothies, adding to breakfast oatmeal or making fruit salads or simple puddings with ice cream.

Batch size

This recipe is based on 1 medium to large watermelon, which should give you 2-4 medium to large jam jars full of preserved watermelons.

Can I scale up or down this recipe?

Yes, of course, you are welcome to make double or triple quantities of this recipe. You can also make less by reducing the recipe based on how much watermelon you have.

Keep the proportions of the ingredients the same, but don’t worry if you add more or less of one or the other ingredients. If you fancy slightly sweeter brine add more sugar.

How to store canned watermelons

Store in cold, dark place away from direct sunlight. Check once in a while for any mould developing. A slight foggy discolouration of water is usually fine, all you need to do is to shake the glass jar to disperse it.

How long will canned watermelons last for?

Canned watermelons should be eaten within 1-6 months. They do have a shorter shelf live since we are not canning them in a hot bath and only using simple pickling method.

But, unlike cold pickling method, we have added aspirin, which helps to preserve the watermelons and keep bacteria away.

Once open, keep the canned watermelons in the fridge (with the lids firmly screwed back on) and make sure that you use them within 7 days.