Hello Dahlia Nerds! 

Over the past couple of weeks, I’ve absolutely loved sharing my tuber storage series with you on Instagram. There’s been so much conversation, so many great questions, and I know storage can be one of those parts of growing dahlias that feels a little daunting at first.

After spending all that time lifting, dividing and labelling our precious tubers, the last thing we want is to lose them over winter!

This is simply how I store my own dahlia tubers, what has worked for me over the years, and the little things I’ve learnt along the way. From choosing your storage container and medium, to temperature, humidity, checking for rot and knowing when your tubers might need a little extra moisture — I’m covering it all.

So grab a cuppa, settle in, and let’s talk tuber storage.

Why Do We Store Dahlia Tubers?

So, why do we go to all the trouble of lifting, dividing and storing our dahlia tubers over winter?

For me, it comes down to one thing — giving my dahlias the best possible start for next season. 

Dahlias are incredibly tough little things, but our cold, wet winter conditions can sometimes be their worst enemy. Leaving tubers sitting in cold, waterlogged soil for months can increase the risk of rot, disease and tuber loss.

By lifting and storing my tubers, I have much more control over their environment. I can keep them protected from excess moisture, regularly check their condition and remove any tubers that show signs of rot or mould before problems spread.

It also gives me the opportunity to reset my dahlia patch each year. I can prepare my beds, improve the soil, reorganise my varieties and start the new growing season with healthy, carefully selected tubers.

And when you’ve spent an entire season growing, photographing, labelling and obsessing over your dahlias, those tubers become pretty precious! 

Do you have to lift and store every dahlia tuber? No. Plenty of growers successfully leave their tubers in the ground over winter, particularly if they have well-draining soil and suitable conditions.

Getting Your Tubers Ready for Storage 

Good storage really starts before the tubers ever go into the coir.

Inspect every tuber – check carefully for rot, soft spots, mould, damage or anything suspicious.

Remove anything unhealthy – one rotten tuber isn’t worth risking the others around it.

Trim away excess roots and stalk – tidy them up so they’re easier to inspect and store.

Make sure each tuber is viable – check that it has a healthy body, neck and crown/eye area.

Deal with minor mould – explain what you do if you find a small amount of surface mould versus actual rot.

Let fresh cuts heal – if you’ve made any cuts while cleaning or dividing, allow the cut surfaces to dry/callus before putting them into storage.

Label, label, label! – make sure varieties are clearly identified before they disappear into storage.

Don’t put wet tubers away – you want them clean and ready, but not sitting wet when they go into their storage medium.

What to Store Your Dahlia Tubers In

The container you choose can make a big difference to how well your tubers hold their moisture over winter. There’s no single container that everyone needs to use — the best option is one that suits the number of tubers you have, your storage space and your climate.

stackable plastic drawers

I love them because they keep everything organised, they’re easy to access, and I can dedicate individual drawers to different varieties. I can simply pull out a drawer and check the tubers without disturbing everything else.

Styrofoam boxes

Are another great option. I’ve used them in the past and found they store tubers really well. They provide some insulation and help create a fairly stable environment. The downside for me is organisation — once you start stacking lots of boxes, getting to the one you need can become a bit of a mission!

Bulb crates

Be careful with ventilation. I’ve also used bulb crates, but I find all the holes around the sides allow too much moisture to escape. If your storage environment is already quite dry, this can increase the chance of your tubers dehydrating and shrivelling.

You definitely don’t need an expensive setup. If you only have a handful of tubers, a plastic tub, an old pot or even a snap-lock bag can work. It’s less about having the fanciest container and more about creating the right little environment around your tubers.

Dahlia Nerd Tip

The goal is to protect your tubers, help prevent them from drying out, and still make it easy enough to check on them throughout storage. 

What Medium Should You Store Your Dahlia Tubers In?

Once you’ve chosen your container, the next question is what are you actually going to pack around your tubers?

The job of your storage medium is simple: help protect your tubers and maintain the right amount of moisture around them while they’re dormant.

For me, my number one choice is coconut coir.

Coconut Coir – My Favourite

I’ve tried a few different storage mediums over the years, but I keep coming back to coconut coir.

I find it holds just the right amount of moisture without staying overly wet. It surrounds the tubers nicely and helps stop them from drying out during storage.

I like to put a layer of coir in the bottom of my container, place my tubers on top, and then completely cover them with more coir.

I also prefer not to have my tubers touching each other. If one tuber does develop rot, giving them a little separation may help reduce direct contact with the tubers around it.

Potting Mix

Potting mix can also be used and, depending on what you have available, it can be a perfectly practical option.

Personally, I find it doesn’t hold moisture quite as consistently as coconut coir for my storage conditions, which is why coir is still my preference.

Wood Shavings

Wood shavings aren’t something I recommend for my setup.

I find they can draw too much moisture away from the tubers, increasing the chance of them becoming dehydrated and shrivelling during storage.

Vermiculite

Vermiculite is another medium you’ll often hear recommended for storing dahlia tubers.

Again, it comes down to your climate and storage conditions. For me, I find it a little too dry, so it isn’t my preferred method.

There Is No One Perfect Medium

This is something I really want to emphasise throughout this guide.

What works brilliantly for one Dahlia Nerd may not work for another.

Storing Your Dahlia Tubers

Now we’ve got our tubers prepared, we’ve chosen our container and we’ve decided on our storage medium — it’s time to actually put them to bed for winter!

This is the method that works for me using my favourite combination: stackable drawers and coconut coir.

Step 1 – Start With a Layer of Coir

I start by putting a good layer of coconut coir in the bottom of each drawer.

You want enough underneath the tubers so they’re surrounded by the coir rather than sitting directly against the bottom of the container.

Step 2 – Add Your Tubers

Next, I lay my tubers gently on top of the coir.

I like to leave a little bit of space between each tuber rather than having them touching. My thinking is simple — if one tuber develops rot during storage, I don’t want it sitting directly against the next one.

Don’t overcrowd them. Give your tubers a little room.

Step 3 – Cover Them Completely

Once my first layer of tubers is in place, I cover them completely with coconut coir.

I like approximately 10 cm of coir over the top of my tubers. This gives them a nice protective layer and helps maintain a more consistent environment around them.

Depending on the depth of your container, you can then continue layering — coir, tubers, coir — making sure the tubers aren’t touching each other.

Step 4 – Label Everything!

Trust me on this one — label as you go!

Once those tubers are covered in coir, one variety looks exactly like another.

I clearly label the front of every drawer with the variety name. If you’re storing multiple varieties in one container, make sure you have a system that leaves absolutely no doubt about what’s what.

There is nothing worse than discovering a beautiful mystery dahlia next season because a label disappeared!

Step 5 – Put Them Into Their Storage Space

Once they’re packed away, I move the drawers into their winter storage position.

The goal from here is to keep the tubers dormant, protected from frost, and neither too wet nor too dry.

And then comes one of the most important parts of storing dahlias…

Don’t completely forget about them!

Things That Can Go Wrong in Storage – And What to Look For

Your tubers are tucked away for winter — but unfortunately, this isn’t the time to completely forget about them!

Even with a storage system that has worked beautifully in previous years, things can still go wrong. Temperature and humidity can change, individual tubers can behave differently, and sometimes a problem doesn’t show itself until weeks into storage.

That’s why I like to check my tubers regularly throughout winter.

You don’t need to pull every single tuber out each time, but having a look through your collection every few weeks can help you catch a small problem before it becomes a big one.

1. Shrivelling and Dehydration

One of the most common things to look for is tubers starting to shrivel.

A little wrinkling doesn’t necessarily mean you’ve lost the tuber. But if they’re becoming very soft, light or extremely shrivelled, your storage environment may be too dry.

This is where your storage medium becomes really important. Check your coir — if it has become completely dry, you may need to carefully add a little moisture.

2. Rot

At the other end of the scale is too much moisture.

A rotting tuber will usually become soft or mushy and may develop a smell. If you find one, remove it straight away.

Check the tubers around it as well, particularly if they’ve been touching.

This is one of the reasons I like to leave a little space between my tubers when I store them.

3. Mould

Seeing mould doesn’t automatically mean your tuber is destined for the bin.

You may occasionally find some surface mould developing during storage, particularly if the conditions are humid.

Have a good look at the tuber underneath. If the tuber itself is still firm and healthy, surface mould can often be dealt with.

Gently using a tooth brush, you can brush the mould off

The important thing is to work out why the mould has appeared. Is your storage medium too damp? Is there too much humidity?

4. Tubers Starting to Shoot

Sometimes your dahlias decide winter is over before you do!

If you start seeing eyes swelling or shoots developing, your storage conditions may be too warm.

A small eye beginning to wake up isn’t necessarily a disaster, but significant growth is a sign that it’s worth checking the temperature of your storage area.

The aim during storage is to keep our tubers dormant until we’re ready to wake them up.

5. Temperature and Humidity Changes

Your storage conditions won’t necessarily stay exactly the same all winter.

A run of particularly cold, warm, wet or dry weather can change the environment inside your storage area.

This is why I don’t rely purely on how the room or shed feels. Keeping an eye on the actual temperature and humidity can tell you a lot about what’s happening around your tubers.

We’ll get into the numbers and the technical side of storage in the next chapter.

Don’t Panic – Observe and Adjust

If you open a drawer and find one shrivelled tuber or a little bit of mould, don’t assume your entire collection is in trouble.

Remove anything that’s clearly rotten, look at what the rest of your tubers are telling you, and adjust your conditions if necessary.

Your tubers are actually pretty good at giving you clues.

Shrivelling? They may be too dry.
Rotting? Things may be too wet.
Shooting? They may be too warm.

The more seasons you store dahlias, the better you’ll become at reading those signs.

Temperature & Humidity – Getting the Balance Right

Now we’re getting into the slightly nerdier side of tuber storage — temperature and humidity! 

The goal is simple: keep your tubers cool enough to stay dormant, but protected from freezing, while maintaining enough humidity to prevent them from drying out without encouraging rot.

Temperature

For dahlia tubers in storage, a good target is generally around 4–10°C.

You don’t necessarily need to hit one exact temperature every day. What we’re looking for is a cool, relatively stable environment without big temperature swings.

If your storage area becomes too warm, your tubers may start waking up early and producing shoots.

If it gets too cold, particularly if the tubers freeze, they can be permanently damaged.

This is why knowing what actually happens in your shed, garage or storage room overnight can be really useful. The temperature at 2 pm may be very different from the temperature at 4 am!

Humidity

As a general guide, around 70–80% humidity 

Your storage medium and container are also creating a small environment immediately around the tuber, so the humidity reading in the room doesn’t tell the whole story.

You don’t need anything fancy — you’re simply trying to understand the environment your tubers are living in.

Check your coir and tubers every week or so

 Dahlia Nerd Tip

Firm, healthy, dormant tubers = you’re doing something right.

I hope this guide has taken some of the mystery out of storing your dahlia tubers and given you the confidence to find a system that works for you. Remember, there’s no one perfect way to store tubers — your climate, your space and your setup will all play a part. Keep an eye on them, learn what your tubers are telling you, and don’t be afraid to make little adjustments along the way. And most importantly, enjoy the process — because before we know it, we’ll be waking them all up again and starting another season of dahlia madness! 

Happy storing, Dahlia Nerds!