Storing dahlias over the winter

Most growers will dig their dahlia tubers in the mid-late autumn or winter, when plants naturally die back or lose their vitality due to the decreasing daylight and lowered temperatures. Some will sell their tubers as soon as they dig, if they are confident they can see tuber ‘eyes’ (where new growth emerges) and don’t have room to store hundreds or thousands of tubers until spring when the eyes sprout.

If you buy and receive tubers during the colder months, there are two options depending on your climate and resources.

1. You can store tubers in a cool, dry place in boxes, in a medium that will allow them to breathe but not dry out or get too moist.

The most common storage mediums are coir or sawdust. Some lightly dampen their coir or compost so that tubers don’t dry out: I have found that in the warm subtropical winters we have, moisture = mold and so I don’t add any moisture to my boxes. If your tubers arrive in a plastic bag, make sure you open the bag so that your tubers aren’t stuck in a moisture trap - even if the bag has holes in it. Check tubers regularly for signs of mold. If you see any, remove that tuber from the box and wash/apply a fungal treatment depending on the severity of the problem, and then re-store separately to the others. Good places for storage are garages and sheds, and places in your house that will stay cool and not get too stuffy.

2. You can put them into pots with your preferred potting mix or compost.

This is a good option for growers in warm climates who want to get a head start on the season. Putting tubers into pots means you can lightly moisten the potting mix and encourage eyes to shoot, and you can move them around your garden as they emerge from the surface depending on the weather conditions. Tubers don’t like to have their roots disturbed though, so make sure you either put them in a big pot if you plan to grow them in pots (30cm diameter or more), or that you transplant into the garden once you can lift the entire plant out of the pot and into its forever home. If you intend to take cuttings, plant the tuber in the pot with it’s neck above the surface so you can cut new shoots accurately.