How do you use salt to preserve vegetables from the garden?

Salt preservation is one of the oldest food preservation methods in human history. Salt draws moisture from vegetables through osmosis, creating an inhospitable environment for the bacteria and moulds that cause spoilage. At high concentrations, salt essentially dehydrates the surface of the vegetable while preserving its structure — the result is a product that keeps for months without refrigeration, heat treatment, or any other processing.

Salt preserving is particularly useful as a method for herbs and for vegetables like runner beans that can be difficult to preserve while maintaining good texture through freezing. It is also an excellent technique when you want to preserve something quickly with no equipment at all — just salt and a jar.

Salt-packing runner beans — a traditional method

Salt-preserved runner beans were the standard method for storing this crop in British kitchen gardens before freezers became universal. The technique is simple: top and tail fresh beans, slice diagonally, and layer in a wide-necked jar alternating with layers of coarse salt — roughly 100g of salt per 500g of beans. Pack tightly, pressing down between layers. As the beans release moisture, the salt dissolves into a brine that preserves the beans below. Seal the jar and store in a cool place. The beans keep for up to twelve months.

Before using, remove the required beans and rinse thoroughly under cold water. Soak in fresh cold water for two hours, changing the water once, to remove most of the salt. Cook without adding any additional salt to the dish. The texture after soaking and cooking is remarkably similar to fresh beans.

Salt-preserved herbs

Soft herbs like parsley, basil, chives, and coriander that lose flavour when dried can be preserved in salt. Wash and dry herbs thoroughly, then blend or chop finely. Mix one part salt with three parts herb by weight and pack into small jars. Press down firmly and seal. The salt-herb mixture keeps in the fridge for six months or at room temperature for two to three months. Use it as you would fresh herbs in cooking, reducing any additional salt in the recipe. Salt-preserved basil retains its green colour and aromatic oils far better than dried basil.

Dry-salting versus brining

There are two approaches to salt preservation: dry-salting, where solid salt is packed directly with the vegetable, and brining, where the vegetable is submerged in a salt solution. Dry-salting (as with beans and herbs above) produces a more concentrated result that functions as a seasoning ingredient. Brining — submerging vegetables in a solution of 5–10% salt in water — produces a milder result, similar to a lightly pickled vegetable. Brined vegetables need refrigeration unless fermentation is allowed to continue and produce lactic acid (at which point it becomes lacto-fermentation rather than plain salt preserving).

Salt ratios and what happens if you use too little

For dry-salt packing, use at least 15–20% of the vegetable weight in salt to achieve reliable preservation. Below this threshold at room temperature, spoilage can still occur in warm weather. Using more salt — up to 25–30% — is safe and more reliable, but the pre-soaking time before eating needs to be longer. For brining at cool temperatures (fridge or cellar), a 5% brine is safe. For room-temperature brine storage without fermentation, use 10% brine. Always use non-iodised salt — sea salt, rock salt, kosher salt, or pickling salt. Iodised table salt inhibits fermentation and can cause discolouration in salt-packed vegetables.