How to Preserve Vegetables at Home: Canning, Freezing, and Fermentation

The courgettes come in August and they do not ask permission. Last year I harvested 47 courgettes from four plants over six weeks. My husband ate as many as he could bear. We gave armfuls to neighbours. We made courgette bread, courgette soup, courgette fritters, stuffed courgettes, and courgette cake.

We still had to compost about a third of them.

This year I did not. This guide explains what I changed.

Home vegetable preservation is not complicated. It is four methods — canning, dehydrating, fermenting, and freezing — each suited to different vegetables and different outcomes. Once you understand which method works for which vegetable, and what equipment each method requires, the rest is practice.

The Four Methods: Which One for Which Vegetable

Pressure Canning

Pressure canning uses steam pressure to raise the temperature inside jars above 100°C (212°F), which destroys botulism spores in low-acid foods. This is the only safe method for preserving low-acid vegetables (beans, peas, corn, carrots, potatoes), stocks, and meats.

What it does well: shelf-stable products that last 1-3 years. No refrigeration required. Large batches processed efficiently.

What it does not do well: delicate textures. Pressure-canned vegetables are soft — fine for soups and stews, not for things you want to eat fresh.

The learning curve: real but not steep. The safety rules are specific and non-negotiable (always use tested recipes, never improvise processing times). See How to Can Food at Home for the full method.

The Presto 23-Quart Pressure Canner (Model 01781) is the standard recommendation for beginners. Dial gauge for precise pressure reading, 23-quart capacity handles 7 quart jars or 20 pint jars in one batch, and spare parts are widely available. The limitation: not compatible with induction cooktops (the 01784 is the induction version).

Water Bath Canning

Water bath canning uses boiling water to process high-acid foods: tomatoes (with added lemon juice), most fruits, jams, jellies, pickles, and chutneys. The boiling water (100°C) is sufficient to destroy pathogens in high-acid environments because botulism spores cannot germinate at pH below 4.6.

What it does well: jams, pickles, chutneys, tomato products. The equipment is a large stockpot with a rack — you probably already own something that works.

What it does not do: low-acid vegetables. Trying to water bath can green beans, peas, or corn is dangerous — the pH is not low enough to prevent botulism growth without the higher temperatures of pressure canning.

Dehydrating

Dehydrating removes moisture from food, preventing bacterial growth and enzymatic deterioration. It works for a wide range of vegetables: courgettes, tomatoes, peppers, onions, mushrooms, root vegetables, leafy herbs.

What it does well: preserves flavour and nutrition better than canning for many vegetables. Dehydrated vegetables take up a fraction of the space. Excellent for soups, stews, and additions to cooked dishes.

The courgette answer: courgette dehydrates well when sliced thin. We slice mine to 4mm, coat lightly in olive oil and seasoning, and run them at 60°C for 8-12 hours. They come out as courgette chips that are genuinely edible as snacks — not just survival food.

The Excalibur 3926TB is the workhorse recommendation for serious home dehydrating. Nine trays, 1.7 square metres of total drying surface, a temperature range of 35-74°C, and the horizontal airflow design that dries all trays evenly without rotating. It is not cheap, but it is the piece of equipment we use most often from October through March.

For lower-volume use, the Cosori 6-tray dehydrator is adequate and costs significantly less.

Fermentation

Fermentation uses salt to create an anaerobic environment in which beneficial bacteria (primarily Lactobacillus) proliferate, acidifying the food and preventing pathogen growth. It works for cabbage (sauerkraut, kimchi), root vegetables, cucumbers, and various other vegetables.

What it does well: genuinely improves the nutritional profile of some vegetables. Creates products with complex flavour that cooking cannot replicate. No equipment beyond jars and salt.

What it does not do: everything. Fermentation suits certain vegetables and certain flavour profiles. It is not a general-purpose preservation method the way dehydrating or canning is.

The entry point: sauerkraut. Shred a cabbage, massage with 2% salt by weight, pack into a clean jar, weigh it down so the cabbage stays submerged below the brine, leave at room temperature for 1-4 weeks. Nothing can go wrong if the cabbage stays submerged — if it goes above the brine and mould grows on the surface, scrape it off and the rest underneath is fine.

Freezing

The method I am not covering in detail here, because it is both obvious and not technically "preserving" in the sense of creating shelf-stable food. But worth noting: blanching vegetables before freezing (brief submersion in boiling water, then ice water) stops the enzymatic processes that degrade colour and texture in the freezer. Unblanched frozen vegetables deteriorate noticeably within a few months; blanched vegetables hold for 8-12 months.

The limitation, which is why I have a full 200-litre chest freezer: it requires electricity. My chest freezer is what the EcoFlow DELTA 2 in the garage is there to protect during power cuts.

Quick Reference: Method-to-Vegetable Chart

The Equipment You Already Have vs What You Need

You probably already have: - Large stockpot for water bath canning - Tongs for handling jars - Oven mitts - Kitchen scales (critical for fermentation, useful for everything) - Sharp knife and mandoline

Worth buying: - Jar lifter (essential for both canning methods — about $10) - Wide-mouth funnel (less mess when filling jars — about $5) - Bubble remover/headspace tool (the thin spatula that removes air bubbles from jars — about $5) - Thermometer (for dehydrating and for fermentation temperature monitoring)

For pressure canning specifically: - A proper pressure canner (not a pressure cooker — different tool with different safety certification)

You do not need: - Expensive electric canning appliances. The Instant Pot is not suitable for pressure canning low-acid vegetables unless you specifically have the Max model and use only tested Instant Pot recipes. Stick to a stovetop pressure canner for reliability.

our August Preservation Schedule

The garden produces unevenly. August in a Somerset garden is a firehose: courgettes, tomatoes, cucumbers, beans, and sweetcorn all at once, faster than any reasonable family can eat them.

My working schedule for August:

Week 1: Tomato focus. Water bath canning for crushed tomatoes (add lemon juice for safety). Some tomatoes dehydrated for soup use over winter.

Week 2-3: Courgette dehydrating. Slice, season, dehydrate in bulk. Start fermenting cabbage for sauerkraut — it takes 3-4 weeks so start early.

Week 3-4: Beans. French and runner beans go in the pressure canner in pint jars with water. Some go in the freezer (blanched). Some become pickled dilly beans via water bath.

Ongoing: Everything that cannot be processed in time goes in the freezer immediately after harvest. Freezing is imperfect but better than composting.

Common Mistakes (Including Mine)

Improvising processing times. Pressure canning times are not suggestions — they are food safety calculations based on jar size, food density, and the specific heat penetration of that food. Processing green beans for 20 minutes instead of 25 minutes because you are tired does not reduce safety by 20%. It potentially creates conditions for botulism growth. Follow tested recipes exactly.

Using commercial jars. Spaghetti sauce jars, peanut butter jars — they look the same as Mason jars. They are not. Commercial jars are not designed for repeated thermal cycling under pressure and can crack or fail to seal. Use only purpose-made canning jars (Ball, Kerr, Kilner, Le Parfait).

Reusing old canning lids. The sealing compound on canning lids is single-use. The jar rings can be reused; the flat lids cannot. Always use new flat lids.

Skipping the bubble removal step. Air bubbles in a jar of pressure-canned food affect heat penetration and can compromise the seal. Run a thin spatula around the inside edge of the jar before lidding.

Expecting fermentation to be foolproof. It mostly is, but "keep the vegetable below the brine" is not optional. If vegetables oxidise above the brine, they discolour and develop off-flavours. If significant mould grows inside the jar rather than just on the surface, discard and start again.

Frequently Asked Questions

Is home food preservation safe?

Done correctly, with tested recipes and proper equipment, yes. The USDA and the National Center for Home Food Preservation have tested thousands of recipes specifically for safety. The main risks come from improvising (wrong processing times, wrong acid levels) or using the wrong equipment (pressure cooker instead of pressure canner).

How long does home-preserved food last?

Pressure-canned and water bath-canned foods: USDA guidance is 1 year for best quality, with food remaining safe beyond that if seals are intact. Dehydrated food stored in airtight containers: 1-3 years depending on moisture content and storage temperature. Fermented food in the refrigerator: weeks to months depending on the product.

Do I need a lot of equipment to start?

Not much. Water bath canning requires a large pot with a lid and a rack — you can start with equipment you likely already own. A jar lifter is worth buying (around £8-10). Pressure canning requires the pressure canner itself, which is a more significant investment.

Related Guides

Pressure canning equipment: Best Pressure Canner 2026: What to Buy First Dehydrating equipment: Best Food Dehydrator 2026: What we Uses What to grow for preservation: How to Start a Vegetable Garden for Food Security

The courgette problem is the best entry point into home preservation. It is the moment most kitchen gardeners realise they need to do something with the surplus, and it is a forgiving crop to start with — you cannot pressure can courgettes safely, but you can dehydrate them, ferment them, freeze them, and make them into everything else. Start with a dehydrator and a bag of courgettes and go from there.