If you’re a gardener, then you understand how important dahlia tubers can be.
These tubers serve as the lifeblood in the growth of dahlias and ensuring that they are looked after will help you enjoy dahlias in the spring season.
But, how do you know when dahlia tubers are dead?
And, how do you bring them back to life if they are dead? Find out below.
What Are Dahlia Tubers?
Dahlia tubers are the dahlia plant’s underground storage organs.
They are generally spherical to ovoid and can vary in size from a few centimeters to more than a dozen centimeters.
The inside is typically white or cream-colored, with a small amount of fleshy tissue.
Did you know? Dahlia tubers have a thick skin that protects against predators and parasites, and it also plays an important role in the plant’s ability to take in water and nutrients.
The Importance of Dahlia Tubers
Dahlia tubers are key to the growth and flowering of dahlias.
The tubers store water and nutrients that are vital to the plant’s survival during drought periods or other adverse conditions.
Dahlia tubers also produce hormones that are important to the growth and development of the plant. Without tubers, dahlias would lose the ability to either create seeds or flower.
How to Care for Dahlia Tubers
If you take care of your dahlia tubers, you will never experience another loss again, and you won’t have to read another article like this.
Soil
Dahlias grow best in a sandy loam soil.
Sandy loam soil drains well, is loose, is full of organic content, and has a neutral pH, which is very important for dahlias.
If your soil is too heavy or clay-like, you can improve drainage by adding some peat moss or sand.
When you are actually putting dahlias into the soil, you want to be sure it is not cold and dry.
You will not want to plant a dahlia until the soil temperature reaches 50 degrees Fahrenheit consistently.
Water
Watering is the most important factor that we need to think about when maintaining dahlia tubers.
The tubers must be maintained moist, but not wet. You will typically want to water deeply and routinely, especially during dry conditions.
When the plant is established, you should be watering your plants as much as three times a week.
The takeaway is that you need to be using well draining soil. If your soil doesn’t drain, the tubers will sit and rot in the water.
Sunlight
Dahlias require a minimum of six hours of sunlight each day in order to grow and flower properly.
Eight hours of sunlight would be even better.
Fertilizer
Dahlias require a lot of nutrients and will need to be fertilized every two weeks through the growing season.
You can give them a water-soluble fertilizer or a slow-released granular fertilizer high in phosphorus to promote blooming.
Signs Your Dahlia Tubers Are Dead
When you lift your dahlias to save them for winter, you might find that they don’t look so great.
But, unless the whole tuber is dead, your tuber will likely grow new sprouts in spring.
Before you toss those unattractive dahlias, take a minute to examine these signs.
1. Bad Smell
Dahlia tubers possess no scent, or sometimes a light, earthy aroma.
If you’ve uncovered your dahlias and they possess the fragrance of pungent rotting flesh? Yes, there’s a “bad” tuber.
You should smell the dahlia flower before digging up your dahlia tubers.
Heads Up! If it smells sweet, or if it smells rancid, there’s a good chance the tuber is dead. If the tuber is dead, the flower isn’t getting nutrients or water to sustain it, and it will wilt and rot.
2. Completely Dry
A dahlia tuber is very similar to a potato in a few ways other than in appearance.
Of course, the texture and shape are similar, but if you cut a potato in half, you can see that there is moisture inside.
A healthy dahlia tuber will appear the same way.
When you cut through a tuber, the knife should take a bit of effort to cut through, but should slice through without too much pulling, to show the moisture inside.
If the inside of the tuber is completely dry and brittle, then the dahlia tuber is dead – and it will not sprout with any new growth in the spring.
Have you Paid Attention? When tubers dry out they will also begin to shrivel and wrinkle. The skin will become completely wrinkly and the tuber will shrink down to half the size, about the size of a pencil lead, with no moisture inside.
There are varying degrees of a tuber drying out, and the point of no return on the drying out is when the sides start to cave inwards and they have dark brown spots.
There is a point of drying out, but when there is just a little wrinkling – you’d be surprised to know that you can still plant those tubers in the spring and see some growth.
3. Moldy
If you find any mold or fungus on the tuber, it’s likely too far gone to save.
If only a small amount of the tuber is affected, cut away the mold and hope that the rest of the tuber is still alive.
Dahlia tubers will grow mold that is white or brown if they are sitting in too much water.
If you dig up your tubers and they are covered in mold, you should amend the soil you are using or your watering schedule.
4. Soft Texture
I informed you that dahlia tubers are similar to potatoes in more ways than one.
When testing a fresh potato, it shouldn’t take too much pressure to squeeze it. The potato should be firm with no soft spots.
The same is true with dahlia tubers. They should be firm and any soft spots would be evidence that they are retaining too much water.
Can You Save a Dead Dahlia Tuber?
Surprisingly, Dahlia tubers are resilient.
Some that I thought were dead and I tossed into the compost piled themselves up the following year.
If you want to do a little work for the chance to save them, here are some options:
- Remove your dahlia tubers from the ground and clean them. Shake out as much dirt as possible, and wash the rest away. Let the tubers dry out completely or dry off completely with a clean paper towel.
- Use bleach or rubbing alcohol to sanitize a sharp knife. Having clean tools prevents further setback or infection.
- Remove all the parts of the dahlia tuber that are very damaged or have an active infection. Cut off the soft spots, dark spots, or dead/stressed spots.
- Now that the insides of the tuber are exposed, apply a sulfur fungicide to the areas you cut to avoid infections from growing and overtaking the rest of your tuber.
- Change out or treat your soil. If your soil has excess bacteria, you should pull it from the garden and change out for new dirt, several bags/pints if that is necessary, or use another fungicide treatment.
- Now that your dahlia tubers are clean and hopefully your soil is treated, these dahlia tubers should now be placed in storage for next spring.
Final Thoughts
Knowing when your dahlia tubers are dead is important not just so you will stop thinking you can plant and grow them next season, but so you can hopefully take steps to avoid it happening in the future.
We identified a few ways to determine if your tuber is dead; looking for dried out skin, mold, or soft as a marshmallow texture. If you have one of these textures, sorry to say, but it is likely too far gone to save.
While it can be disappointing to have a dead-looking dahlia tuber, there are still actions you can take to save it.
If you are willing to do some extra work, you should be able to revive your dahlia and hopefully enjoy its blooms the following season.