How to store dahlia tubers before the frost reduces them to blackened tatters

Famed for their riotous ruffles and dinnerplate-sized blooms, it's little wonder so many of us want to learn how to store dahlia tubers. It is, after all, the easiest way to fill your garden with these timeless treasures... and for free, no less.

It's all well and good knowing how to plant dahlia tubers, but you won't get those non-stop blooms all midsummer and autumn long unless you've lifted and stored them properly over winter.

Any gardener worth their salt knows that timing is everything when it comes to outdoor tasks. So, if you're wondering when to lift dahlia tubers, hold your horses: you should actually wait for the first frost before taking action.

'Frost reduces dahlias to blackened tatters, so [that] will be [the best] time to bring them in. However the tubers will not be harmed unless the ground freezes, so do not panic,' says Monty Don reassuringly via his popular gardening blog.

Once you've gotten your tubers out of the ground, though, it's important you set to work quickly on prepping them for storage... particularly as excess moisture can cause rot.

With that in mind, then, how best to go about this important gardening task? We've consulted the experts to bring you the ultimate guide...

What you'll need

While some gardening jobs come with a long shopping list in tow, you don't need all that much when it comes to storing your dahlia tubers. Just be sure to have the following to hand...

• a breathable container, such as a cardboard box, wooden crate, or even brown paper bags from Amazon
• dry packing material (something like Gro-Sure Vermiculite from Amazon works well)
• a plant mister, like this Fine Mist Spray Bottle with Top Pump Trigger from Amazon

Step-by-step guide

Amateur gardeners will be pleased to know that there aren't all too many steps involved in our How To Store Dahlia Tubers 101 guide. Still, if you want to keep them and grow dahlias in pots or garden borders, it's worth paying attention to them all the same...

1. Dry the tubers

Once you've removed your dahlia tubers from the ground, it's important to shake off any excess soil without the use of water.

Once this is done, you'll want to 'let the tubers air dry in a cool, dry place for a few days, ideally keeping them upside down,' says Christopher O'Donoghue, one of the co-directors at Gardens Revived. 'This will help reduce the risk of rot during storage.'

Christopher O'Donoghue

A gardener with almost two decades of experience under his belt, Christopher set up Gardens Revived with his brother, Andrew, in 2018 to create a thriving family business. Together, they have worked on residential gardens, listed buildings and gardens, flower shows and large estates with some exceeding 70 acres – many with historical significance.

2. Trim and inspect

The next thing you need to do when learning how to store dahlia tubers is simple enough; take the time to look at them and examine them carefully.

'Once you've trimmed any remaining stems, you need to check the tubers for damage,' says Christopher. 'Be sure to discard any that are soft, shrivelled, or show signs of rot.'

3. Get packing

Once you've got the cream of the crop together, it's time to store your dahlia tubers in earnest and both Christopher and Monty are in agreement; you want to keep them as dry as possible for this bit.

'Look for a breathable container, such as a cardboard box or wooden crate,' says Christopher, ' and then pack in your tubers, taking care to layer them with sawdust or vermiculite. This will help to keep them insulated and prevent moisture build-up.'

Monty adds that a 'tray or pot packed with old potting compost' works just as well here.

4. Find the perfect spot

When it comes to overwintering your dahlia tubers, you'll ideally want to store them in something like in a frost-free shed or greenhouse.

'Find a location that stays between 4–10°C, such as a basement, garage, or garden shed, and avoid areas that might freeze or get too warm,' says Christopher.

5. Check them periodically

When it comes to storing dahlia tubers, this isn't a case of out of sight, out of mind. Rather, you need to keep checking in on your plant babies throughout the winter.

'The idea is to keep them cool but frost-free, dark and dry but not to let them dry out completely or else the tubers will shrivel,' says Monty.

'I lightly water mine after layering them into large pots or crates and then check them every month to see if any are mouldy or shrivelling up.'

FAQs

What is the best way to store dahlia tubers for the winter?

The best way to store dahlia tubers for the winter is to make sure they stay dry in a cool, dark spot. Christopher O'Donoghue of Gardens Revived advises storing them in paper bags, cardboard boxes, bulb crates, trays, or pots filled with old potting compost, vermiculite, sharpsand or sawdust.

'Throughout the winter, check on the tubers occasionally,' says Christopher. 'If any start to shrivel, lightly mist the packing material to add moisture. Remove any tubers that show signs of rot.'

Can you store dahlia tubers in an unheated garage?

You can store dahlia tubers in an unheated garage, shed, greenhouse, or frost-free spot that stays between 4–10°C. Aim for somewhere that's dark, dry, and with good air circulation, to help prevent rot or any unpleasant diseases taking hold.

Now that you know how to store dahlia tubers, you can sit back and wait for the first frosts to strike (remember, you shouldn't begin the lifting process until the top has fully died back).

Once you've got them bundled up and safe from the chilly outdoors, you can sit back safe in the knowledge that you have a plethora of pretty flowers sat ready for replanting in spring!