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Broken Dahlia Tubers: How To Tell if They Are Worth Keeping

Broken Dahlia Tubers: How To Tell if They Are Worth Keeping

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Native to Central America, perennial tuberous dahlias have flourished in the climate of North America. These tall plants display magnificent blooms, adding beauty to the late summer and autumn seasons.

Dividing dahlia tubers is the ideal way to propagate them, but those tubers have to be in good condition to sprout a new bushy plant.

Will broken dahlia tubers grow? Dahlia tubers are quite sensitive and will only grow if they have intact necks, a potion of crown, and at least one eye. If the dahlia tuber has no crown, neck or eyes, it will not grow even if it looks intact with no scars or blemishes on the skin. Throw it away, and plant a tuber with a crown, neck, and eyes.

Not all the dahlia tubers you dig out from a mature plant or buy at a garden center will grow into healthy plants. Some will not even grow at all. Read more to find out how to identify healthy dahlia tubers.

How To Identify Viable Dahlia Tubers

Dahlias are complex and intricate plants, not just in their bushy foliage but also in what grows underground.

When you have a mature dahlia that you want to propagate, you’ll usually dig out some of the tubers, divide them, and plant them, but this is not always as easy as it sounds. Some tubers won’t grow at all even though they look good.

Difference Between Dahlia Clumps and Tubers

Tubers are dahlia’s energy-storage units. The plant will use that stored energy to start new growth the next spring.

Dahlia tubers grow in clumps attached together. You’d need to divide those clumps every few years because the original tuber that started the mother plant often dies and decays. 

Parts of a Dahlia Tuber

Dahlia tubers are lumps of tissue with a neck at the top and roots at the other end. The neck often has one or more growing points called eyes. Both the neck and the eyes are crucial for growing a new plant out of the tuber.

The crown is located at the top of the neck. Since eyes will form from the crown, it is vital to leave as much of the crown intact when dividing tubers. No crown = no eyes = no dahlias.

When you plant the tuber, you want to keep the neck facing upward. If you can’t tell which part of the tuber is up, just lay it on its side, and cover it with soil. The shoots will grow and breach the surface of the soil on their own.

What To Look For

When choosing a dahlia tuber to plant, you might be tempted to pick the largest tuber since it has a lot of stored energy to promote healthy and fast growth, but when it comes to dahlia tubers, size doesn’t matter.

What really matters is the neck of the tuber and the number of eyes on it. 

Without a neck, the tuber won’t grow no matter how large and fat it is, so always make sure the neck is intact on the tuber. Even a broken tuber with a healthy neck has a good chance of growing. 

The other thing to look for is the number of eyes or growing points on the crown. The more eyes the tuber has, the more likely it is that it will grow. Ideally, the tuber should have between 4 and 5 eyes.

How To Tell if Dahlia Tubers Are Dead

Although dahlia tubers look more or less the same, you can still tell when a tuber is dead or too bad to grow. Here are the signs to look for when identifying a good dahlia tuber to plant.

  • Mold: Dahlia tubers are quite sensitive. If you see mold on the skin of the tuber, that’s a bad sign that the tuber is either dead or dying. Even if it looks good in every other way, the chances of this molded tuber growing are slim.
  • Dry and Brown: The healthy dahlia tuber is dark yellow and packed with juices. So, if the tuber looks withered and dry with brown skin, that means the tuber is most likely already dead and should be tossed away.
  • Bad Odor: That’s another sign that you have a dead or diseased tuber on your hands. If the odor coming off the tuber is funky or rotten, get rid of the tuber. A healthy tuber has an earthy smell or no odor at all.
  • Soft Texture: A good tuber is firm in your hand and won’t give in under your thumb. A bad tuber has a squishy texture due to loss of moisture. You can cut off a piece from the bottom of the tuber to be sure the inside shows no signs of rot.

Dahlia Tubers Without Eyes

The eyes on the dahlia tubers are the growing points where shoots develop and grow into whole plants. Without those eyes, the tuber is just a storage unit to feed the plant when it comes out of dormancy.

If your tuber has no eyes, don’t dig it out, and don’t try to plant it. It just won’t grow.

Soft Dahlia Tubers

Soft or squishy dahlia tubers have lost their moisture due to exposure to high temperatures and the absence of moisture in the soil.

The tubers can also get soft when they’re damaged, infected with fungi or mold, or dying for some reason or another. Dispose of those soft tubers when dividing your clumps.

When To Dig Up Dahlia Tubers

Even under unfavorable weather conditions, the dahlia tubers continue to grow in the soil.

In the winter, the plant’s crown dies back and is unlikely to survive the frost, but the tubers underground are still healthy and viable. That’s the best time to dig them up and store them throughout the winter to plant the next spring.

When To Divide Dahlia Tubers

You should divide dahlia tubers every 2 to 3 years. The original tuber of the plant often decays over time, which means that the plant will stop growing and eventually die.

Divide your dahlia clumps in the winter or early spring. If you get frost, you should dig out the clumps and divide them in the early winter once the first frost has killed the foliage.

How To Separate Dahlia Tubers

You need to take precautions when separating dahlia tubers. The tubers are quite sensitive and might lose their vital parts during the process. Here’s how to separate dahlia tubers in easy steps.

  1. Start digging 1 foot away from the stalk of the dahlia, and avoid damaging the roots while digging.
  2. Hose away the dirt from the root system to uncover the tubers.
  3. Dig out the entire root system of the dahlia including the tuber clumps. Don’t pull them out until you have dug out the soil around the whole root ball.
  4. Locate the mother tuber, and get rid of it.
  5. Look for eyes on the neck of the tubers, and then cut off individual tubers with sterilized shears, leaving the neck intact and keeping as much crown as possible on each one.
  6. Cure any cuts or scars on the body of the tuber with sulfur to prevent infections.

When To Plant Dahlia Tubers

The sensitive tubers won’t survive frost or harsh cold conditions. Plant them indoors in the early spring for a jumpstart on the growing season, and transplant them to the garden when the soil becomes workable and the threat of the last frost is over.

Related Questions:

Do Dahlia Tubers Multiply?

A single dahlia tuber can multiply and produce between 3 and 10 tubers in the span of a year. You can plant the new tubers as long as they have their neck and eyes intact.

Can You Plant a Single Dahlia Tuber?

You can plant a single dahlia tuber as long as it has at least one eye on the neck. The tuber will grow and produce more tubers after the plant matures.


A dahlia tuber with a healthy body, intact neck and crown, and a few eyes on the neck is more likely to grow than one missing any of those parts.

Make sure the tuber doesn’t have a bad odor or squishy texture or is covered with mold before planting it.