By Elizabeth Spence
Dahlias are such gorgeous flowers. They come in an enormous variety of shapes, heights and colours. (Geek alert: if you’re interested in why there are so many variations in dahlias, look up “dahlia octoploid” and “dahlia jumping genes.”)
Stunning in the flower bed or in containers, they can be real showstoppers or they can be expressions of the noblest simplicity
But there’s a price to pay if you want to keep them for next year. In our climate where it freezes heavily during the winter, we have to mollycoddle them. We have to dig the tubers up, do things to them and find the perfect place to store them.
The correct storage is essential, because if the slightest frost gets them, they rot and become a mushy mess and this obviously happens if you leave them in the ground over winter as well.
If they are too warm in storage they may rot, and they will certainly start to bud out way before planting time.
In fact, the main reason that many of our readers don’t even bother trying to overwinter the tubers is that they simply don’t have a suitable storage space.
One of our readers summed up his overall attitude to dahlias in a fairly straightforward way: “I wouldn’t touch them with a bargepole! Too much fuss and bother!”
Yet many people love them so much that they will go to any lengths to keep the tubers alive throughout the winter with the hope of another stunning display next year. And, of course, it’s cheaper than buying new ones every year.
Here is what some of our readers do:
Valerie Cunningham says:
I usually dig them after the first frost and remove as much soil as possible. After a good rinse I lay them out to get relatively dry and put them in a crate lined with newspaper. I always farm them out to someone with an unheated basement for the winter.
Magi Nams says:
To store my dahlias, I dig up the tubers after the first real frost, cut the stems back to about two inches, gently hose all the soil off the stems and tubers, cut off any damaged or rotting tubers, allow the tubers to dry completely, and store them in my basement cold room, in brown paper bags filled with lightly dampened sphagnum moss. A couple of times during the winter, I check the tubers for rot. If the moss is completely dry, I lightly dampen it with a spritzer again.
Jeanne Forbes says:
Rinse some mud off with the hose and include some detergent if you have earwigs. Let them dry out – they should be quite dry before storing and they need to be spread out some, so they won’t rot. Store in a basket in cold room for the winter.
Silvana Valiani says:
I dig them up, put them in cardboard boxes and keep them in my barn. My barn is insulated and the sheep and bunnies keep the temperature around 45/50F. Mostly, they all survive and I replant in the spring.
Jennifer says:
I dig them up, set them out to dry, wipe/brush off any soil I can, then store them in paper bags in my garage.
What I do:
Cut off foliage, dig them up, shake off excess soil, cut off any rotting bits, leave them to dry for a few hours, sprinkle with cinnamon (anti-fungal and anti-bacterial), place upside down in paper bags with dry potting soil and store in my basement. Spritz occasionally through the winter if they are drying out.
Mine are still (October 20) blooming away, and there hasn’t been a hard frost. No need to dig them yet.
Here is the generally accepted order of doing things, although there are arguments about most of these steps:
- Let the frost blacken the foliage and then cut it off leaving a 2-6” stem. In other words, wait for the first noticeable frost;
- Cover the stems to stop the water getting in;
- Wait a couple of weeks before digging. Some maintain that this is necessary so that the tubers develop their “winter skin” – i. e. harden up, and that new eyes will start to form;
- Make sure they are labelled;
- Dig up the tubers, being careful not to slice or spear them with your fork or spade;
- Hose the soil off completely;
- Disinfect pruners, snips, etc; Most seem to use a 10% bleach solution.
- Cut off any damaged or rotting bits, the stringy roots and tiny tubers;
- Divide them, making sure there is a piece of stem with at least one eye on each one. (This is a job and a half.)
- Dry them, frost-free, on a rack or similar with good ventilation for a day or two;
- Some sprinkle sulphur powder on them;
- Pack them.
- Store between about 4 and 10 degrees C with 70-80% humidity;
There are so many steps here that it looks a bit overwhelming. Here’s some advice:
You will see that none of us around here goes to these lengths, yet we all manage to have wonderful displays every year. We do, it is true, lose a few tubers during storage. But not enough to make any difference.
To be quite honest, I can’t be bothered with a lot of what is generally recommended. For the decades I’ve been growing dahlias, I’ve kept it all very simple but not as simple as Silvana: she digs them up, puts them in cardboard boxes and keeps them in her barn. The end. This is in fact the very old-fashioned way of doing things.
We do NOT hose them down or divide them at this time. In fact, Jennifer makes the point that since the winters can be very dry here, it is better not to get rid of all the soil. It actually helps to stop the tubers drying out.
Some dahlia growers will be horrified by this, but all I can say is that our methods work for us.
At this time of year garden burn-out isn’t far off. I do want to keep my dahlias and it’s sometimes a miracle that I dig them up at all! I have about a 90% storage success rate, so I do wonder if it’s necessary to do all the other stuff.
In the end, all experienced growers have a method that works for them, so it’s a question of experimenting to see what works for you. For me, the simpler the better.
General Observations
LABELLING
This is something that is often forgotten: putting labels on the dahlias before you dig them up.
There are always times when the labels or the tubers have slipped while I was moving them, or I’ve mishandled them or something, or the odd tuber has fallen off the clump, and I’ve no idea what they are.
There are various ways of labelling them but I have found that writing the name on surveyors’ or painters’ tape and wrapping it around the stems before digging is fairly successful – and cheap. When I remember to do it.
All sorts of commercial labels are available, of course, but here are some really economical ones. Just attach them to the stems or place them securely (!) in between the tubers in a clump:
Many people write the dahlia names directly on the individual damp tubers. I suppose you could do this on the tubers in a clump as well.
I will also write the names of the dahlias on the paper bags I store them in, so that I can identify them without having to open everything.
STORAGE OPTIONS
- in paper bags, carboard boxes, paper-lined crates, plastic totes, feed bags, plant pots, wrapped in newspaper, in zip-lock bags;
- in a medium: coarse vermiculite, shredded paper, peat, shavings, dry pine needles, moist sand, pet bedding or nothing at all;
- in plastic wrap. In this method people usually clean, dry and disinfect individual tubers, wrap them in cling-film and store them in a box or tote.
How I do it:
It is worth stressing again, that the main goal in storing dahlia tubers is to keep the temperature between about 4 -10 C and the humidity about 70-80%.
Some people store their tubers in the regular fridge. Others say they lose them if they do that. Many do store them in a bar fridge which seems to be able to hold the correct temperature.
The overall message is – if you can’t find appropriate storage, there’s really no point even trying.
THE DREADED LEAFY GALL AND CROWN GALL
These are a bacterial infections of dahlias which make growers’ blood run cold. With leafy gall, the bacteria instruct the plant to put out masses of little shoots all clumped together near the bottom of the stem. Crown gall produces cork-like masses where the tubers meet the stems
“Throw the whole lot away,” we are told. “Disinfect everything in sight, get rid of the soil the infected tubers were grown in.” Panic stations again!!!
As with so many things in gardening, there is disagreement here. Some say leafy gall, anyway, is not such a big deal. I’m not getting into that argument. I leave it to you guys to toss or not to toss.
If, at the end of the dahlia season, you don’t have a suitable storage place for your tubers, there are other things you can do with them. You can use them in the kitchen. Yes! Dahlia tubers are edible. Here’s a recipe for dahlia tuber bread from a dahlia grower in the States:
Dahlia Tuber Bread Ingredients:
Preheat your oven to 350 degrees.
2 eggs
1 cup of sugar
2 teaspoons of vanilla extract
1/2 cup of cooking oil
Mix those ingredients in a mixer and then add the following:
1 and 1/2 cups of all-purpose flour
½ teaspoon baking powder
½ teaspoon salt
½ teaspoon baking soda
2 teaspoons cinnamon
½ teaspoon all spice
¼ teaspoon cloves
¼ teaspoon nutmeg
Mix well. Peel your dahlia tubers. Using a box grater, shred the dahlia tubers. You will need 1 cup of shredded dahlia tubers. Fold that into your batter. Grease and flour a 9×5 loaf pan. Pour the batter into the prepared pan and bake it at 350 degrees for about 1 hour. It is done when a toothpick comes out clean. I let it cool in the pan for about 10 minutes and then place the dahlia bread loaf on a serving plate. Enjoy!
Other things you can do if you don’t have appropriate storage for your dahlias, is find someone who lets you park them with them until you retrieve them in the spring.
Or you can dig them up yourself and give them away, or, better still, ask a dahlia addict to come and dig them up and take them away themselves.
Keep in mind that there are some people who can’t live without these gorgeous flowers. If you donate them to friends and acquaintances, your reward will be that they will love and remember you forever!
Copyright © 2024 Elizabeth Spence