By Magnus von Kageneck, cellar master · Updated: August 2026
Every year in September I get the same question, usually over the garden fence: “Magnus, my grapes — can you make wine from them?” The honest answer: yes, and better wine than most people think. Garden grapes almost never fail because of the grape. They fail because of three avoidable things: picked too early, too much air, too little measuring of acidity.
1. When to pick — measure, don't guess
The berries taste sweet weeks before they are ripe. What counts is the must weight: squeeze out a handful of berries and measure the juice with the Oechsle must hydrometer. Below 60 °Oechsle the wine turns out thin and sour; from 70–80 °Oechsle it gets seriously good. Home-garden grapes without much sun often stay at 55–65 — then you're allowed to help things along with sugar: around 250 g of sugar per 10 litres raises the must weight by about 10 °Oechsle, which later gives a good 1.2 % vol more alcohol.
2. Mash or juice?
White grapes you press, then ferment the juice. With black grapes all the colour sits in the skins — so they are crushed and fermented as a mash (in German: “Maische”), and only pressed after a few days. That, incidentally, is the word this shop owes its name to. A splash of pectic enzyme in the mash breaks down the pectin and draws out noticeably more juice and colour.
3. Acidity — the underrated lever
Garden grapes often bring 10–12 g/l of acidity; a wine drinks pleasantly at 6–8 g/l. Measure it with the acidometer — it's a five-minute job — and deacidify overly sour musts with calcium carbonate. Conversely, a must that is too flat gains definition with a little lactic acid. Exactly how to do both is explained in the article on acidity.
4. Ferment as usual — only cleaner
Cultured wine yeast instead of spontaneous fermentation (all the more so in home gardens with visiting wasps — they bring in acetic acid bacteria), yeast nutrient, a fermenter fitted with an airlock, 18–22 °C. After the main fermentation: first racking off the yeast, fining with kieselsol and gelatine, stabilising before bottling. We have described every single step in our Wine School — from sulphuring to sweetening without bottle bombs.
What you can realistically expect
Depending on the pressing, 10 kg of garden grapes give you 6–7 litres of must and, in the end, a good 5 litres of wine. The first year will be decent, the second good — because by then you know how your grapes tick. My neighbour is now on his fourth vintage. These days he no longer hands me questions over the fence, but bottles.
Related in the shop: Making Wine and Measuring & Testing