How to Preserve Fruit and Vegetables

A good garden often grows more than you can eat. In August a few tomato plants can outrun the kitchen, and by September the courgettes just keep coming. Preserving turns that glut into food for the months ahead.

Here are the main ways to do it in a UK kitchen, what each suits, and how long things keep. Bottling has a few safety rules that really matter, and they’re all here. For tested bottling recipes and times, the US National Center for Home Food Preservation (NCHFP) is the go-to source.

Which preserving method suits each fruit and vegetable?

Each crop has one or two methods that suit it best. Tomatoes bottle well, while runner beans are better frozen or salted. Here’s a quick guide.

Produce	Bottling	Drying	Salting	Sugar	Freezing
Tomatoes	Good, with added acid	Good	No	No	Good
Courgettes	No	Good	No	No	Fair
Runner beans	Pressure canner only	Good	Good	No	Good
Beetroot	Pickled, or pressure canner	Fair	No	No	Good
Apples	Great	Great	No	Great	Good
Pears	Great	Good	No	Great	Fair
Raspberries	Good	Fair	No	Great	Great
Strawberries	No tested method	Good	No	Great	Good
Chillies	Pickled only	Great	Fair	No	Good
Onions	Pickled only	Great	No	No	Good
Plums	Great	Good	No	Great	Good
Blackberries	Good	Fair	No	Great	Great

Handy tip: Preserve your crops as soon after picking as you can. They lose sweetness and go soft quickly once picked.

Bottling in Kilner jars: the water bath method

Bottling means packing fruit into jars with hot syrup or juice, then boiling the sealed jars in a big pan of water. The heat kills moulds and yeasts and pushes the air out, so the lid seals as it cools. It’s only safe for fruit and other acidic foods.

Equipment needed

• Jars with new seals or lids. Two-piece screw-top lids, like Kilner ones, are what the tested times are for. With clip-top jars, follow the maker’s instructions and fit a new rubber seal every time.
• A deep pan with a rack, deep enough to cover the jars by at least 2.5cm of water
• A jar lifter or strong tongs
• Clean tea towels

Step-by-step water bath method

1. Wash the jars in hot soapy water and keep them hot until you fill them
2. Wash the fruit, peel if needed, and cut it into even pieces
3. Pack it into the hot jars, leaving about 1cm at the top
4. Pour over hot syrup or fruit juice. About 200g sugar per litre of water makes a very light syrup
5. Run a clean plastic spatula round the inside to let air bubbles out
6. Wipe the rims clean and fit the lids
7. Stand the jars on the rack and cover with at least 2.5cm of water
8. Bring to a rolling boil and only start timing once it’s boiling
9. Lift the jars out and leave them to cool, undisturbed, for 12-24 hours
10. Check the seals (see below)

Cover the jars with at least 2.5cm of water and only start timing once it’s at a rolling boil. This method is for fruit only.

Do you need to sterilise jars before bottling?

Not if the jars will be boiled for 10 minutes or more, as the boiling does it for you. For anything processed for less than 10 minutes, sterilise the jars first. Boil them for 10 minutes, or heat them in a 140C oven for 15 minutes, and fill them while hot. Don’t put rubber seals or lids in the oven.

Processing times for water bath bottling

These tested times work for most UK homes, up to 300m above sea level. “Pint” and “quart” are US jar sizes: a pint is about 470ml and a quart about 950ml. Treat a 500ml jar as a quart. Don’t use jars bigger than a quart.

Fruit	Pack	Pint	Quart
Apples (sliced)	Hot	20 minutes	20 minutes
Pears (halved)	Hot	20 minutes	25 minutes
Plums (halved or whole)	Hot or raw	20 minutes	25 minutes
Raspberries, blackberries	Raw	15 minutes	20 minutes
Gooseberries, currants	Hot	15 minutes	15 minutes
Rhubarb (stewed)	Hot	15 minutes	15 minutes
Tomatoes (whole, in water, with lemon juice)	Hot or raw	40 minutes	45 minutes

There’s no tested method for bottling strawberries, so freeze them or make jam.

Tomatoes always need extra acid, because some aren’t acidic enough on their own. Add 1 tablespoon of bottled lemon juice per pint jar, or 2 per quart. Use bottled juice, not fresh lemons, as it’s always the same strength.

How do you know a jar has sealed?

The middle of the lid should dip down slightly and not pop back when you press it. If a jar hasn’t sealed, either redo it within 24 hours with a new lid, or keep it in the fridge and eat it within a few days.

Important: Never bottle plain vegetables like beans, carrots, peas, sweetcorn or beetroot in a pan of boiling water. They can carry botulism spores that survive boiling. Freeze them, use a pressure canner, or pickle them with a proven recipe.

Once cool, a sealed lid dips slightly in the middle and doesn’t pop back. Any jar that hasn’t sealed goes in the fridge to eat soon.

Pressure canning for low-acid vegetables

A pressure canner is the only safe way to keep plain vegetables in jars. Run at 10 PSI on a weighted gauge or 11 PSI on a dial gauge, it gets hot enough to kill the botulism spores that survive boiling.

Pressure canners are common in America but hard to find in the UK. Buy one made for canning, with a rack and a gauge, and follow its manual exactly. Have a dial gauge checked every year, as one that reads wrong can leave food unsafe.

Can you use a pressure cooker or multi-cooker instead?

No. An ordinary pressure cooker is too small and heats and cools too fast for the tested times to work. Electric multi-cookers aren’t made for canning either. Without a proper canner, freeze your vegetables instead.

Pressure canning times (up to 300m altitude)

Vegetable	Pint	Quart
Green or runner beans	20 minutes	25 minutes
Carrots (sliced or diced)	25 minutes	30 minutes
Peas (shelled)	40 minutes	40 minutes
Sweetcorn (whole kernel)	55 minutes	85 minutes
Beetroot (hot pack)	30 minutes	35 minutes
Asparagus	30 minutes	40 minutes

As with fruit, treat a 500ml jar as a quart.

Botulism prevention rules

Botulism is rare, but the NHS describes it as a serious, life-threatening illness. These simple rules keep you safe:

1. Never bottle plain vegetables without a pressure canner.
2. Only use proven recipes and times. Never make up or shorten them.
3. Don’t rely on home pH strips to tell you a recipe is safe.
4. Throw away any jar with a broken seal, bulging lid, spurting liquid or odd smell.
5. When in doubt, throw it out. You can’t see, smell or taste the danger.

Is freezing the safest way to preserve vegetables?

For most garden vegetables, yes. There are no exact times to get right, so it’s very forgiving. Blanch most vegetables first. A quick dip in boiling water stops them losing colour, flavour and crunch in the freezer.

Drop the prepared vegetables into boiling water, then cool them fast in iced water. Green beans need 3 minutes, peas 1.5 minutes, sliced carrots 2 minutes and courgette slices 3 minutes. Sweetcorn needs 4 minutes on the cob before you cut the kernels off. Drain well, freeze on trays, then bag up. Our freezing garden produce guide goes through each crop.

Blanch, cool fast in iced water, then freeze on trays before bagging. Runner beans need about three minutes in the pan.

Dehydrating fruit and vegetables

Drying takes out enough water to stop moulds growing. Dried food takes up very little room and keeps in airtight jars. It’s one of the easiest methods and suits lots of crops.

Equipment options

• Electric dehydrator: stacking trays with a temperature dial. The most reliable choice. Set it to about 60C.
• Oven: on its lowest setting with the door propped open a little. It works but uses more energy and dries less evenly.
• Air drying: good for herbs and thin chillies hung somewhere warm and airy. Most UK homes are too damp to air-dry fruit.

Dehydrating times and temperatures

Produce	Prep	Temperature	Time
Apple rings	Core, slice 5mm thick	60C	8-12 hours
Tomatoes	Halve, scoop out seeds	60C	10-14 hours
Courgette slices	Slice 5mm thick	60C	8-10 hours
Onion rings	Slice 5mm thick	60C	6-10 hours
Chillies	Whole or halved	60C	8-12 hours
Herbs	Bunch or strip the leaves	35C	2-4 hours
Peas	Blanch 2 minutes, drain	60C	8-10 hours
Runner beans	Slice, blanch 3 minutes	60C	10-14 hours
Mushrooms	Slice 5mm	60C	6-8 hours

Times depend on thickness and how full the trays are. Dried fruit should feel leathery and bend without being sticky. Dried vegetables should be crisp and snap. Anything not dry enough will go mouldy.

Slice apple rings about 5mm thick and dry at around 60C. They’re done when they feel leathery and bend without being sticky.

How long does dried produce keep?

Dried fruit keeps about a year somewhere cool. Dried vegetables keep about half as long. Pack them into airtight jars once cool, add a date label, and store somewhere cool and dark. Check after a week: if there’s condensation inside, dry them a bit more.

Making fruit leather

Fruit leather is fruit purée spread thin and dried into a bendy sheet. It’s a fun way to use soft fruit that’s too ripe for jam making.

Basic fruit leather method

1. Prepare 500g of ripe fruit (strawberries, raspberries, blueberries, plums, or a mix)
2. Blend until smooth. Sieve out the seeds if you like
3. Add a tablespoon or two of honey or sugar if it’s sharp
4. Spread it 3-4mm thick on a silicone mat or lined dehydrator tray
5. Dry at 60C for 6-12 hours, until it’s no longer sticky and peels off easily
6. Roll it up in baking paper and cut into strips
7. Keep it in an airtight box for up to a month, or up to a year in the freezer

Fruit leather is ready when it’s no longer sticky and peels off easily. Roll it in baking paper and cut it into strips.

Best fruit combinations

• Strawberry and apple (apple helps the texture)
• Raspberry and pear
• Blackberry and apple
• Plum and cinnamon
• Rhubarb and ginger (add extra sugar, as rhubarb is very sharp)

A 500g batch fills one big tray.

Salt preserving vegetables

Salting draws water out of vegetables so spoilage can’t take hold. Salted runner beans are the classic British way.

Dry salting method for runner beans

1. Wash and slice 1kg of young, fresh runner beans
2. Layer salt and beans in a clean jar: salt, beans, salt
3. Use about 250g of coarse salt for 1kg of beans
4. Press down firmly after each layer
5. Finish with a thick layer of salt
6. Cover and keep somewhere cool and dark
7. Over a few days the beans shrink and make liquid. Top up with more beans and salt

To use them, rinse and soak in cold water for about 2 hours, changing the water twice. Then cook as normal. Throw away any that turn slimy or smell bad.

Layer beans and coarse salt, pressing down well, and finish with a thick layer of salt. Top up as the beans shrink over the next few days.

Sauerkraut and other ferments

Sauerkraut uses much less salt, about 20-22g per kilo of shredded cabbage. That lets friendly bacteria ferment the cabbage and turn it sour. Our pickling and fermenting guide covers ferments and vinegar pickles.

Handy tip: Use coarse pickling or preserving salt. The anti-caking stuff in table salt can make brine cloudy.

How long do vegetables in oil keep?

Only a few days, unless you freeze them. Keep fresh vegetables, garlic or herbs in oil in the fridge and eat them within 4 days. Oil shuts out the air, and vegetables left in oil at room temperature can grow botulism.

Safe ways to enjoy vegetables in oil

• Chargrilled courgettes and roasted peppers: cover with oil and herbs, keep in the fridge and eat within 4 days, or freeze in portions
• Garlic and chilli oils: make small batches, keep them in the fridge and use within 4 days

Shop-bought garlic in oil is made under careful controls, which is why it can sit on a shelf. Home versions can’t be made safe the same way.

Sugar preserving

Sugar preserving uses lots of sugar to stop moulds growing. It’s how jam, marmalade and candied fruit keep.

Other sweet ways to preserve:

• Fruit syrups: dissolve sugar in fruit juice and boil briefly. Keep in the fridge and use within a few weeks, or freeze.
• Candied peel: soak citrus peel in stronger and stronger sugar syrups over 7-10 days, then dry in a low oven.
• Fruit in syrup: bottle it using the water bath times above.
• Fruit pastes (membrillo): cook quince with sugar until really thick, set it in moulds and wrap in baking paper.

Low-sugar jams don’t keep as well, so keep them in the fridge once opened.

Vacuum packing

Vacuum packing sucks the air out of food bags. It stops freezer burn and keeps dried food dry, but it doesn’t make food last longer in the fridge.

How to use vacuum packing safely

Produce	In the fridge	In the freezer
Blanched vegetables	Same as unpacked: a few days	Up to a year
Soft fruit	Same as unpacked: a few days	Up to a year
Fresh herbs	Same as unpacked	Up to 6 months
Dried produce	Not needed	Not needed: keep in a cool cupboard

In the fridge, treat vacuum-packed food just like anything else. The real benefit is in the freezer, where flat bags save loads of space too. See our guide to freezing garden produce.

Handy tip: Freeze soft fruit on a tray before vacuum packing so the berries don’t get squashed.

Seasonal preserving calendar for UK gardens

Here’s what to preserve, and how, through the harvest season.

Month	Harvest	Best ways to preserve
June	Strawberries, gooseberries, broad beans	Jam, freezing, bottling gooseberries
July	Raspberries, blackcurrants, peas, beans	Jam, freezing, bottling berries
August	Tomatoes, courgettes, plums, runner beans	Bottling, drying, chutney, freezing, salting
September	Apples, pears, blackberries, beetroot	Bottling, drying, sugar preserving, pickling
October	Pumpkins, squash, late apples, chillies	Drying, freezing, apple storage
November	Quinces, medlars, stored roots	Membrillo, storing roots in a clamp

Our monthly harvest guide shows what to pick and when.

Equipment and shelf life compared

Method	You’ll need	How easy	Keeps for
Freezing	Freezer, bags or boxes	Easy	Up to a year
Water bath bottling	Jars, deep pan with rack	Medium	Use within a year
Pressure canning	Pressure canner, jars	Hard	Use within a year
Drying	Dehydrator or oven	Easy	Fruit a year, veg about 6 months
Salting	Jars, coarse salt	Easy	Several months, kept cool
Sugar preserving	Preserving pan	Easy to medium	Depends on the recipe
Vegetables in oil	Jars, fridge	Easy	4 days in the fridge, or freeze
Vacuum packing	Vacuum sealer	Easy	Depends on fridge or freezer

Common mistakes when preserving

Using damaged or old seals

Rubber seals perish and two-piece lids are made to be used once. Use new ones every time. A seal that looks fine can still fail.

Using unvalidated recipes or times

Times depend on the food, the jar size and how it’s packed. Family recipes and old cookbooks may not be safe. Use tested times from the NCHFP or the jar maker. No tested time? Freeze it instead.

Getting the headspace wrong

Food swells as it heats. Too little space and food gets under the lid. Too much and air is left in the jar. Either way the jar may not seal. Leave the gap your recipe says, usually about 1cm for fruit and tomatoes.

Storing preserves in warm or light locations

Warmth and light spoil preserved food. Keep jars and dried food in a cool, dark cupboard, never on a sunny windowsill. Our easy recipes for home-grown vegetables have ideas for using it all up.

Next, why not try making jam from garden fruit?

Warmth and light fade colour and flavour. A cool, dark cupboard keeps your preserves at their best.

Frequently asked questions

What is the safest way to preserve vegetables at home?

Freezing is the easiest safe way. Blanch beans, peas, carrots or sweetcorn, cool them quickly and freeze. Bottling plain vegetables in jars is only safe with a proper pressure canner and a proven recipe, because boiling water isn’t hot enough.

How long does bottled fruit last in Kilner jars?

Use it within a year. Keep sealed jars somewhere cool and dark. Check the seal before opening and throw away any jar that has lost its seal, is bubbling or smells off. Once opened, keep it in the fridge and eat it within a few days.

Do I need special equipment to preserve food?

Not much for most methods. Bottling fruit needs jars with new seals or lids, a deep pan with a rack and a jar lifter. A dehydrator helps with drying, but a low oven works. Freezing, salting and sugar preserving need only a normal kitchen.

Can I use a normal oven for dehydrating?

Yes. Set it to its lowest setting and prop the door open a couple of centimetres with a wooden spoon. Lay the slices on wire racks and swap the trays round every couple of hours. It works, but it’s less even than a dehydrator and uses more energy.

Which fruits and vegetables should not be water bath canned?

Plain vegetables like beans, carrots, peas, sweetcorn, beetroot and asparagus. Boiling water doesn’t get hot enough to make them safe. Freeze them, use a pressure canner, or pickle them with a proven recipe that has plenty of vinegar.

How do I know if preserved food has gone off?

Look for bulging lids, broken seals, cloudy liquid, bubbles, mould or odd smells. Liquid spurting out when you open it is a warning sign too. Never taste anything you’re unsure about. The dangerous kind of spoilage can’t be seen or smelt, so if in doubt, throw it out.

What is the difference between water bath and pressure canning?

A water bath boils jars at 100C, which is fine for fruit. A pressure canner gets much hotter, which is needed to make plain vegetables safe in jars. Always use the method your proven recipe says, and never swap one for the other.