If you’re making homemade jams, chutneys, cordials, or fermented drinks, sterilising your bottles and jars is essential to prevent unwanted bacteria or mould from spoiling your hard work. The process is simple, but it’s important to do it correctly for food safety and the best results.

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Why Sterilise?

Even brand-new jars can contain dust, invisible bacteria, or lingering smells. Sterilising ensures your containers are clean and safe, extending the shelf life of your preserves and keeping their flavour pure.

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Method 1:

In the Oven

1. Preheat the Oven
   Set your oven to 140°C (275°F) or Gas Mark 1. You don’t want it too hot—glass can crack if the temperature changes too quickly.
2. Wash the Jars or Bottles
   Clean jars and bottles in hot soapy water, then rinse well.
3. Dry and Heat
   Place the jars (and/or glass bottles) upright on a baking tray.
   ⚠ Important: Do not place any plastic caps, rubber seals, or lids in the oven—they will melt or warp. Keep these aside to sterilise separately.
4. Bake
   Heat for 20 minutes. Keep them in the oven until you’re ready to fill them to prevent re-contamination.

Tip:

It’s best not to put jars or bottles on their side in the oven during sterilisation.

Here’s why:

• Uneven heating – When glass lies on its side, hot air can’t circulate evenly inside, and any residual moisture may pool rather than evaporate.
• Risk of rolling – Round bottles can roll, risking breakage.
• Potential for contamination – If the open mouth of the jar touches the tray or rack, it’s no longer sterile.

For oven sterilising, jars and bottles should be placed upright, spaced apart on a baking tray, so the heat can circulate inside and around them fully.

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Method 2

On the Stove (Boiling Water)

1. Wash First
   As before, wash thoroughly with hot soapy water and rinse.
2. Boil
   Place jars and bottles in a large pan, fully submerged in water. Bring to a boil and keep boiling for 10 minutes.
3. Remove Safely
   Use tongs to take them out and place upside-down on a clean tea towel to drain.
4. Lids & Caps
   This is the best method for metal lids and plastic caps—boil them for 5 minutes instead of putting them in the oven.

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Extra Tips

• Always fill jars and bottles while they’re still warm to avoid thermal shock.
• Work on a clean, clutter-free surface to reduce contamination.
• Use sterilised utensils for filling to keep things as clean as possible.

With these methods, your glass bottles and jars will be perfectly prepped for whatever delicious creation you’re making next.

Safety Disclaimer:

• Always handle hot jars, bottles, and lids with heatproof gloves or tongs to avoid burns.
• Do not place cold glass directly into a hot oven, as sudden temperature changes can cause cracking or shattering.
• Only use heatproof glass jars and bottles in the oven—never place plastic, rubber, or non-oven-safe materials inside.
• Keep children and pets away from the work area during sterilisation.
• This guide is for general information only. Always follow manufacturer instructions for your specific jars, bottles, and oven

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