Lift your dahlias as soon as the first frost has blackened the foliage, at the latest by the end of November. Cut the stems back to about 10 centimetres, let the tubers dry upside down for a few days, then store them in boxes of dry soil, sand or straw in a dark, cool, frost-free place.

Why do dahlias have to come out of the ground?

Dahlias come from the highlands of Mexico and are not hardy. If the ground freezes down to the tubers, they turn soft and rot. In most gardens in Switzerland and its neighbouring countries, frost penetrates deep enough into the soil in winter, so lifting them is the safe choice. Only in very mild spots with light, free-draining soil can a thick mulch of around 15 centimetres over the tubers be enough. In heavy, wet soil the tubers rot even without frost.

How do I recognise the right moment?

The most reliable sign is not the date but the foliage: after the first frosty night it turns black and collapses. By then the plant has stored its energy in the tubers. If frost comes late, lift the tubers by the end of November anyway, so a sudden cold snap does not freeze them in the ground.

How do I lift the tubers without damaging them?

  • Push a garden fork into the soil about 20 centimetres around the plant and lift the root ball carefully.
  • Do not pull on the stem, because the crown breaks easily.
  • Remove the soil by hand and cut away damaged or already soft parts, because rot starts at wounds during storage.
  • Stand the tubers upside down for a few days in an airy, frost-free place so water can drain from the hollow stems.

How do I store dahlias properly?

Lay the dried tubers in shallow boxes and cover them with dry potting compost, sand, straw or newspaper. A cool cellar, a frost-free garage or a garden shed that you also cover with fleece on cold nights are all suitable. Check the tubers every few weeks and remove soft or mouldy pieces at once.

Whether frost is on its way in your garden depends on location and weather, not on the calendar. The page How Maluna works shows how Maluna relates this kind of context to your plants.