Food & Drink, Kitchen Staples

How to Sterilise Glass Jam Jars Four Ways

Today let me show you how to sterilise glass jam jars four different ways – in the microwave, in the oven, in an aga, and in the dishwasher.

I love pickling and preserving fruit and vegetables, and making delicious jams and marmalade.  However, I find I frequently have to rummage through old recipes to remind myself of how to sterilise jam jars correctly.

So partly to help myself, and partly to help any readers also a bit stumped by sterilisation, I’ve put together this quick and easy guide.  It shows you exactly how to sterilise glass jam jars in the oven, microwave, dishwasher, and aga.  Something to suit all preferences, if you will!

Why Do You Need to Sterilise Jam Jars?

Sterilising jam jars is a really important part of the jam, preserve, and pickle-making process.  For a start, there is a risk of botulism if you don’t sterilise your jars correctly.  And secondly, your preserves will last longer. They’ll last up to a year, as sterilisation removes any bacteria, yeast, or other organisms from your jar. This means these organisms are less likely to grow and spoil your hard work before you have got a chance to eat your jam.  Therefore, don’t be tempted to skip over the sterilisation stage!

how to sterilise jars

How To Sterilise Jam Jars In Any Situation

Here are my failsafe four methods to sterilise jars, whatever your situation:

In the Oven

To sterilise your jam jars in the oven:

1.  Heat your oven to 140°C /  275°F / Gas Mark 1.

2.  Wash your jars and lids in warm soapy water.  Next, rinse well to ensure no traces of soap.  Do not dry your jars.

3.  Place a piece of baking paper on a baking tray and place your wet jars on it.  Ensure the jars aren’t touching each other.

4.  Place in the oven and heat for twenty minutes.

5.  Whilst the jars are in the oven, place your wet lids in a saucepan of water, and boil for twenty minutes.

6.  That’s you done!  If your jam/pickle/preserve hasn’t finished cooking once the twenty minutes are up, keep your jars in the oven with the door closed and keep the lids in the saucepan of water.  Cold jars will crack or shatter if you put hot food/liquid in them so you want to keep them warm.

Please note, to sterilise Kilner jars with rubber seals then it’s best to remove the rubber seal and boil that in water.  This is because rubber doesn’t tend to react well to being dried in hot air.  The jar (minus the rubber seal) can be placed in the oven with no problem.

How to Sterilise Jam Jars In the Microwave

This method of sterilising jars in the microwave is a good quick trick to have up your sleeve.  Particularly if you find that you’ve used up all of your jars that you sterilised in the oven and still have jam/pickle/preserve waiting to be jarred!  Just don’t put metal lids or jars with metal clasps in your microwave.  That would be very bad!

If you’re recycling old jars, make sure you’ve removed any label that might have had any kind of metallic paint/ink on it too.

Now that we’ve gotten the safety stuff out of the way, the quickest way to sterilise jars in the microwave is just to wash your jar in hot soapy water, and rinse as before.  Then place your wet jar in the microwave on full power for about 45 seconds (or until bone dry).  Once it’s done in the microwave, make sure fill you fill the jar whilst it is still hot.

If you’re in a proverbial pickle and need to sterilise metal lids quickly, don’t worry.  Even just washing them in warm soapy water then placing them in a bowl of boiling water while you microwave your jars quickly is probably sufficient.

In the Dishwasher

To sterilise jam jars in your dishwasher just put your dishwasher on at its maximum temperature.  My dishwasher has a top heat of 70°C. Then allow it to run through a full wash and dry cycle so that the jars and lids are bone dry and still hot when you take them out.  Here’s my guide to plastic-free dishwasher detergent in case it’s of interest!

Sterilising jars in a dishwasher does take a bit of planning though, so be warned!  Bearing in mind the jars have to be warm and bone dry when you jar up your preserve, you have to know exactly how long it takes for your dishwasher to complete a whole wash and dry cycle. I personally prefer the oven method, as it takes less planning.

In an Aga

I don’t have an Aga.  However, I have it on good authority that to sterilise jars in an Aga simply wash your jars in the same manner as above.  Then place the jars in the simmering oven of your Aga for twenty minutes, again in the same manner as you would the oven.  Again, make sure you fill your jars whilst they are still hot.

Other Things to Bear In Mind

There are a few other pointers to bear in mind when sterilising jars.

  • Firstly, check your jam jars for any cracks or nicks before you start.  If you find any put them in your glass recycling.  The high temperatures involved in sterilisation could cause them to smash or shatter.
  • Sterilisation liquid or tabs are fine for sterilising jars intended for pickles or chutneys, or anything else strongly flavoured.  However, I would avoid them if you’re making delicately flavoured jams.
  • Any lids that are a bit rusty-looking should be put in your recycling.

I hope you’ve found this sterilisation guide useful!  If there are any hints or tips I’ve missed out on, or if you do things differently then do share in the comments below!

ps: here are some preserve recipes you might like: easy organic marmalade, blackberry and vanilla jam, and quick pickled cucumber with fennel flowers.  I’ve also pinned this delicious-sounding recipe for the plum season this year. You might like it too!

Food & Drink, Summer

Pickled Cucumber Recipe with Fennel Flowers

pickled cucumber recipe
pickled cucumber recipe

Here’s an easy pickled cucumber recipe, for when cucumbers are at their very best.

We’ve got an overabundance of flowering fennel right now. It takes over quite a large corner of our garden. However, rather than dig up the bulbs to eat, the flowering fennel is something we want to keep. The bees and wasps absolutely love it.  As well as helping wildlife, attracting wasps to our garden helps keep our caterpillar population at a minimum – companion planting for the win!

I like to use fennel fronds in cucumber salad. Served with feta cheese, they are delicious. However, I’ve never done anything with fennel flowers.  

I’ve always wondered if I could perhaps share the fennel flowers with the bees and wasps. As such, I thought about pickling cucumbers with fennel instead of traditional dill.  I gave it a go and was pretty delighted with the results.  So delighted in fact, that I thought I’d share the pickled cucumber recipe with you guys.  The fennel gives the pickled cucumber that extra flavour hit.  And the good thing is the pickled cucumber recipes uses only a few fennel flower heads so there will be plenty left for the bees and wasps!

cucumber recipe idea

Before You Start

One note before you get started. I made one large jar and five small jars of cucumber pickle, so make sure you’ve got enough jars to hand for your pickled cucumber!  You also want to ensure your lids are vinegar proof – meaning there isn’t any metal that can touch the vinegar.  If you don’t use vinegar-proof lids, the vinegar can react with the metal lid, giving the pickled cucumber a metallic taste.

If you’re using old jars that you’re recycling, then look for lids with a plastic lining in them.  The good thing is if you’re using jars that previously contained any kind of pickle, chutney, mayonnaise, or tomato sauce then the lids are sure to be vinegar proof.  The only lids I’ve seen which aren’t vinegar proof tend to be lids from honey jars.  Kilner clip jars are also good for pickle making.

summer preserving ideas
pickling and preserving
cucumber with fennel

Easy Pickled Cucumber Recipe with Fennel Flowers

adapted from Debora Robertson

Easy Pickled Cucumber Recipe with Fennel Flowers

This delicious and easy pickled cucumber recipe with fennel is so easy to prepare and perfect for adding a touch of summer flavour to any meal.
Prep Time 15 minutes
Cook Time 10 minutes
Total Time 2 hours 10 minutes
Servings 6 jars


  • 3 cucumbers
  • 500 ml cider vinegar
  • 400 ml white wine vinegar
  • 120 ml water
  • 4 tablespoons sugar
  • 2 teaspoons mustard seeds
  • 1 teaspoons peppercorns
  • 6 garlic cloves finely sliced
  • 2-3 tablespoons salt


  1. Slice the ends of off your cucumbers and discard, then slice the cucumbers into coins, roughly 1.5cm thick.
  2. Sprinkle salt on a plate and cover the plate with one layer of the slices of cucumber. Sprinkle salt on top of that layer then add another layer of cucumber on top. Continue salting and layering your cucumber until all of your cucumber has been salted. I ended up using two plates. Leave for two hours to macerate.
  3. Whilst you are waiting on your cucumbers to macerate it’s best to make the pickling brine. To do this it’s really easy – simply add the vinegars, water, sugar, garlic slices,, mustard seeds and peppercorns to a pot and heat gently over a low heat, stirring until the sugar has dissolved. Once you’ve done this leave this mixture to cool.
  4. After about 1 hour and forty minutes sterilise your jars and lids. To sterilise jars see this guide to sterilising jars.
  5. Once your two hours is up rinse the salted cucumbers and pat dry with clean tea towels.
  6. Place the cucumbers into your jars and evenly divide your fennel flowers between the jars. Pour the brine over the cucumbers and fennel, leaving just half a centimetre from the lid of the jar. Seal and leave in a cool dark place for 48 hours at the absolute least, but preferably a week. The longer you leave it the greater the taste, so patience really is a virtue!
  7. The jars should keep for around 3 months unopened. If you want you can place your sealed jars in a bath of boiling water for 5 minutes to process them – this should mean they will keep for around a year, unopened. They do soften a bit using this method.
  8. Once opened, keep your pickles in the fridge and use within a fortnight.

I hope you enjoy this easy pickled cucumber recipe!  It’s definitely a firm favourite in our house!