One of the best ways of growing Dahlias is in pots, this way you can plant them in a well draining potting mix and keep them safe from pests like slugs and snails. Growing them in pots is especially useful if you have clay soil, as Dahlias do need a well draining soil and they will struggle to grow in clay.
You can leave your Dahlias in pots over the winter, as long as you store them indoors in a cool, dry, and dark environment. Only leave out your potted Dahlias during the winter if your area doesn’t get any frost. There is no need to water your potted Dahlias over the winter, as at this point the tubers are dormant and will not actually absorb the water. If you water them while they are dormant you increase the risk of them rotting or mold growing in the pots.
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The main thing that tends to kill off Dahlias in the winter is frost, they are really sensitive to it and even a light frost can damage the tubers. Once the tubers get frost damaged they usually will go soft and rot, oftentimes the healthy tubers without any frost damage can also rot if they are in direct contact with rotting tubers. Dahlias in pots that are left outside during the winter are prone to frost damage and rot.
If you do not have enough space indoors for the potted Dahlias then under no circumstances stack the pots one on top of the other. This way the tubers will get damaged due to the increased pressure, instead just dig the tubers up and store them separately. If your Dahlia tubers are soft then check out my recent article Soft Dahlia Tubers ( Top 4 Reasons ).
Can You Leave Dahlias In Pots Over Winter?
Yes, you can leave dahlias in pots over winter, but it’s important to take proper precautions to ensure their survival. Dahlia tubers are not as hardy as bulbs, so they are more susceptible to frost damage. Before winter arrives, it’s recommended to lift the dahlia tubers from the pots and store them in a cool, dry place where the temperature stays above freezing, such as a basement or garage. Shake off excess soil from the tubers and allow them to dry for a few days.
Then, place the tubers in a box or container filled with dry peat moss, vermiculite, or sawdust to protect them from moisture and prevent drying out. Store the tubers in a location with consistent temperatures around 40-50°F (4-10°C). Periodically check on the tubers during winter to ensure they remain in good condition. In spring, when the risk of frost has passed, you can replant the tubers in pots or directly in the ground for another season of beautiful dahlias.
Leave The Dahlias In Pots And Bring Them Indoors
It is highly recommended that you bring the potted Dahlias indoors during the winter, even if your area doesn’t get any frost during the winter. Winters can be fairly humid, with a lot of rain, and as Dahlia tubers will not be able to absorb all the excess moisture they might start to rot. On the other hand, if your area gets below freezing during the winter, then the potted Dahlias that are left outside will get frost damage which will eventually kill off most of the tubers.
There are a lot of people who can over winter Dahlias in the soil, by adding a generous amount of mulch on top of them. Although this approach will not work for potted Dahlias, as pots are not well insulated and will allow the cold to penetrate the soil. If you want to know what will happen if you do not divide your Dahlias then check out my recent article What Happens If You Don’t Divide Dahlias? ( Top 4 Outcomes ).
Store The Potted Dahlias Indoors In A Cool Environment During The Winter
A cool environment is extremely important for Dahlias, this way they can go dormant during the winter. If the temperatures are too high then the potted Dahlias will not be able to go dormant and they will simply continue growing. The problem is that this new growth will be extremely weak, as the plants try to reach any source of light. By continuously sprouting in storage, the Dahlias tubers can run out of energy and will not be able to sprout once spring comes.
Avoid storing potted Dahlias in rooms that are constantly hot, like the kitchen or living room. Make sure to store the potted Dahlias on the ground and not on a shelf, as the temperatures tend to be higher near the ceiling. For more information about Dahlias sprouting in storage, check out my recent article Dahlia Tubers Sprouting In Storage ( Top 3 Reasons ).
Cover The Potted Dahlias
It is highly recommended that you cover your Dahlias during the winter, and make sure that the tubers do not get any direct sunlight. Oftentimes Dahlias tubers can sport in storage if they get direct sunlight, this is not ideal as the stem of these plants will be tall and leggy. In addition to this, covering up the potted Dahlias also limits the evaporation which means that the tubers are less likely to dry out in storage.
Just make sure that the cover allows air to circulate, if air doesn’t circulate then mold might form in the pot which can kill off the Dahlia tubers.
Do Not Water The Potted Dahlias During Winter
Dahlia tubers have everything they need in order to sprout, this includes a lot of water as well. Once the Dahlia tubers go dormant they do not actually need additional water as they have more than enough to survive in the tubers. Dormant Dahlias will not be able to absorb excess water, and oftentimes watering them during the winter will lead to tuber rot. The ideal place to store Dahlias during the winter is in a cool and dark environment, and increasing the humidity might also lead to mold growing in the pots.
Some people do water their potted Dahlias during the winter with 1-2 cups of water, for the most part, this is not necessary. In rare circumstances, Dahlia tubers can dry out during the winter, although the good news is that once they get some water in the spring most of the dried-out tubers will bounce back. To put it simply, if you water your potted Dahlias during the winter then they might rot, and if you don’t then they might dry out.
With that being said I still don’t recommend you to water them, as dried-out tubers can bounce back, but a couple of rotten ones will kill off all the healthy tubers as well.
Bring Out The Potted Dahlias In Spring
Once all danger of frost has passed, in the spring, you can simply bring out the potted Dahlias. At this point, most people will drench them in water, do not do this, as the tubers might rot. Instead, wait for the Dahlias to grow a couple of leaves, usually, this is an indication that it is safe to water them as the tubers will start actually absorbing the water with their roots. From here on you can care for your Dahlias just as you do with your other plants.
Key Takeaways
- There is no need to water the potted Dahlias during the winter.
- Only leave outside your potted Dahlias if your winters do not go below freezing.