Swiss tomatoes bottom out in August, when domestic supply peaks and a crate of ripe cooking tomatoes drops to around CHF 1.50/kg. Turning that glut into passata now — canned in jars or frozen in tubs — locks in summer prices for the whole winter, instead of paying spring rates for sauce from October onward.
The maths is simple. Twelve 500 ml jars hold roughly six litres of sauce, and six litres needs about 10 kg of tomatoes. At the August crate price that is around CHF 15 in tomatoes; the same six litres made from CHF 5.50/kg spring tomatoes would run close to CHF 55. One afternoon of chopping and simmering banks a saving of about CHF 40 on a single batch, before you count what you would otherwise spend on branded bottled passata.
Why does batching passata in August pay off
Two things line up in August that rarely coincide the rest of the year: tomatoes are cheap, and they are actually good. Domestic supply is at its peak, so the fruit is ripe, full-flavoured and heavily discounted — the opposite of the pale, pricey imports on the shelf in March. Buy a crate, spend an afternoon, and you convert a short-lived seasonal low into sauce that keeps for a year.
There is a waste angle too. Ripe tomatoes bought cheap in bulk are exactly the food that spoils on the counter before you get to it. Swiss households throw out around 119 kg of food per person every year, much of it fresh fruit and vegetables, according to the Federal Office for the Environment (BAFU). Cooking a glut down into passata is one of the most reliable ways to turn a food that is about to spoil into a shelf-stable jar that lasts for months.
When are Swiss tomatoes actually cheapest
Swiss tomato season runs from June to October, but the price floor lands in August and early September, when field and greenhouse harvests overlap and volume Aktionen appear across the chains. Loose tomatoes on promotion sit around CHF 2.50/kg; very ripe tomatoes sold by the crate at markets, farm shops and some Aligro branches go lower, often near CHF 1.50/kg. Our guide to Swiss tomato season tracks the monthly price curve in detail.
Compare that with spring, when almost every tomato is imported from Spain, Morocco or the Netherlands and shelf prices climb to CHF 5–6/kg. Swiss food prices already run about 61% above the EU average, and out-of-season produce is where that gap bites hardest. Passata is simply how you buy at the August price and eat at it in February.
How much passata will a crate of tomatoes make
Tomatoes are mostly water, so the yield is lower than most people expect. A kilo of ripe tomatoes cooks down to roughly 600 ml of pourable passata — a little more than one standard 500 ml jar. Reduce it into a thick sugo and you land closer to 400 ml; keep it looser and barely cooked for the freezer and you get a touch more.
Rule of thumb: plan about 2 kg of tomatoes for every litre of sauce you want on the shelf. A standard 5 kg crate makes roughly six 500 ml jars of pourable passata, or four jars of thick sugo.
What does a jar of homemade passata really cost
Honestly, it depends what you compare it against. Here is the per-jar cost of three home methods, all starting from an August crate at CHF 1.50/kg, with two shop-bought references for context.
| Method | Tomatoes per batch | Yield | Cost per 500 ml jar |
|---|---|---|---|
| Freezer (blitz, freeze in tubs) | 5 kg | ~3 L (6 tubs) | ~CHF 1.55 |
| Water-bath canned, pourable | 10 kg | ~6 L (12 jars) | ~CHF 1.65 |
| Water-bath, reduced sugo | 10 kg | ~4 L (8 jars) | ~CHF 2.30 |
| Bought own-brand passata (reference) | — | 500 ml | ~CHF 1.50 |
| Bought branded passata (reference) | — | 500 ml | CHF 2.50–3.50 |
The takeaway: homemade passata will not undercut the very cheapest own-brand jar on ingredients alone, but it beats branded passata comfortably and buries the cost of making sauce from out-of-season tomatoes. Factor in the quality and the zero-waste use of a glut, and the case is easy.
Jars or freezer: which way should you store it
Both work; they trade effort for freezer space. Freezing is foolproof — blitz, cool and pour into tubs or flat freezer bags, and you are done. The only cost is a slot in the freezer and the electricity to keep it cold. Water-bath canning frees up the freezer and gives you jars that sit in a cupboard for a year, but it asks for a little more care around sterilising and acidity.
The one non-negotiable for canning is acidity. Passata sits right at the pH border where preserving gets risky, so add one tablespoon of lemon juice (or a pinch of citric acid) per 500 ml jar before sealing. Would rather skip the chemistry? Freeze it — the freezer sidesteps the acidity question entirely.
Our broader guide to preserving the summer glut covers sterilising, sealing and shelf life across jams, pickles and sauces if you want to put up more than tomatoes.
How do you make and put up a batch, step by step
The method is simple and scales to whatever crate you bought. Set aside two or three hours and do it in one go:
- Wash and core the tomatoes and cut out any bruises. No need to peel if you will pass the sauce through a food mill or sieve later.
- Roughly chop and add to a wide, heavy pot with a splash of water so nothing sticks before the juices run.
- Simmer 20 to 40 minutes until soft and broken down — longer if you want it thicker.
- Pass through a food mill (passatutto) or sieve to remove skins and seeds. This is what makes it passata rather than crushed tomatoes.
- Reduce further on the heat if it is thinner than you like, stirring so it does not catch.
- To freeze: cool fully, portion into tubs or bags, label with the date and freeze flat.
- To can: add one tablespoon of lemon juice to each sterilised 500 ml jar, fill leaving 1 cm headspace, seal, and process in a boiling water bath for 35 to 40 minutes.
- Cool and check the seals. Store sealed jars in a cool, dark cupboard; anything that did not seal goes in the fridge to use within days.
Because it is a one-afternoon job that stocks the shelf for months, passata is a natural anchor for a wider batch-cooking routine — make the sauce, then build sugo, soups and bakes on top of it all winter.
How much does batching actually save over a winter
Take a household that gets through about half a litre of tomato sauce a week — one pasta night plus the odd soup or bake. Over the six months from October to March that is roughly 13 litres.
- Batched in August from a crate at CHF 1.50/kg: about 22 kg of tomatoes, so roughly CHF 33 in tomatoes plus lids and energy — call it CHF 40 for the winter's sauce.
- The same 13 litres as branded bottled passata at CHF 3/L: about CHF 39 — near break-even, but lower quality.
- The same 13 litres made fresh from spring tomatoes at CHF 5.50/kg: about CHF 120.
Against fresh out-of-season tomatoes, batching saves on the order of CHF 80 across the winter; against premium bottled sauce it roughly pays for itself while giving you far better passata and no waste. The saving grows the more sauce your household eats — and it is biggest of all when the tomatoes were a garden glut or a giveaway crate that cost nothing to begin with.
Frequently asked questions
When are Swiss tomatoes cheapest?
From late July to September, when domestic field and greenhouse tomatoes flood the market and undercut imports. August is the low point: expect around CHF 2.50/kg on Aktion for loose tomatoes, and CHF 1.50/kg or less for a crate of ripe cooking tomatoes at markets and farm shops. By spring the same tomatoes are imported and cost CHF 5–6/kg.
How much passata from 1 kg tomatoes?
Roughly 600 ml of pourable passata, a little over one standard 500 ml jar. Reduce it into a thick sugo and you get closer to 400 ml; freeze it barely cooked and you keep a touch more. Plan about 2 kg of tomatoes for every litre of sauce you want to store.
Is homemade passata cheaper than jarred?
It depends on the comparison. Against the cheapest own-brand passata at about CHF 1.50 for 500 g, homemade from full-price tomatoes barely breaks even. Against branded passata at CHF 2.50–3.50 a litre, or fresh sauce from out-of-season tomatoes at CHF 5–6/kg, homemade from a crate of August tomatoes wins clearly — and the quality is not comparable.
How do I store passata safely?
Two safe routes. Freeze it in tubs or bags for up to a year, which is simplest and foolproof. Or water-bath can it in sterilised jars with one tablespoon of lemon juice per 500 ml to guarantee acidity, then store the sealed jars in a cool, dark cupboard for up to 12 months. Never rely on the oven or dishwasher alone to seal jars, and discard any jar with a bulging lid or off smell.
Does Eini track tomato prices?
Yes. Eini's algorithm follows fresh produce prices and Aktionen across Coop, Migros, Lidl, Aldi, Denner and Aligro, so you can see when Swiss tomatoes hit their August floor and time your batch. It then folds the sauce into your meal plan and grocery list automatically.
Plan smarter, spend less with Eini.
Real prices from Coop, Migros, Lidl, Aldi, Denner & Aligro. Smart meal plans. Automatic grocery lists.
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