Ideally dividing dahlias should happen every 2-3 years, as at this point the tubers have grown and multiplied to a point where they are already competing with the other tubers. A lot of people tend to divide their Dahlias once they pull them out of the ground during the autumn, this is the safest time to do so. On the other hand, there are people who can overwinter their Dahlias in the ground and never divide them.
If you don’t divide your dahlias and the clump of tubers grows larger, then the plant’s energy will get divided among the numerous stems, resulting in fewer flowers and less vibrant blooms. To promote optimal blooming, it is recommended to divide the dahlia clump every few years. By dividing the tubers, each plant will have more space and resources to thrive, leading to a greater abundance of beautiful and vibrant flowers.
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Dahlias that grow in the wild are not being divided by anybody, yet they still grow well. Although Dahlias that grow in the wild tend to have a lot smaller flowers like the dinner plate Dahlias for example. The main reason why people divide their Dahlias is to keep the plants as healthy as possible and to eliminate the completion between the Dahlia tubers. The more tubers a Dahlia clump has the higher its needs are going to be.
Each tuber needs to be able to access nutrients and water, which tends to be rather hard if the Dahlias are overcrowded. Old tubers can simply die off, and the new ones will absorb their nutrients, but this also exposes them to diseases and rot as well. One of the main reasons why you should divide your Dahlias is to check for soft tubers, for more information check out my recent article Soft Dahlia Tubers ( Top 4 Reasons ).
What Happens If You Don’t Divide Dahlias?
If you don’t divide dahlias regularly, several issues may arise. Over time, clumps of dahlias tend to become crowded, resulting in reduced flowering and smaller blooms. The lack of division can lead to competition for nutrients, space, and sunlight among the plants, resulting in weaker growth and decreased overall vigor. Additionally, overcrowded clumps are more susceptible to diseases and pests as airflow and sunlight penetration become limited. Dividing dahlias every few years, ideally in early spring or after the first frost in fall, helps rejuvenate the plants, promotes better flowering, and allows for proper spacing and airflow.
They Will Get More Sprouts
The more tubers a Dahlia clump has the more sprouts it can grow, usually, this means a bushy Dahlia although it depends on how large the actual clump is. Once these sprouts start to mature you can easily thin them out, this way only the strongest sprouts are allowed to grow which will result in larger or more flowers. On the other hand, if you do not thin them out then the plants will be smaller, and not all of them will be able to flower due to the increased competition for nutrients. Even if you do not divide your dahlias, you should still check the tubers, for more information check out my recent article How To Tell If Dahlia Tubers Are Dead? ( Top 7 Signs ).
They Can Get Overcrowded
Overcrowded Dahlias tend to perform relatively badly, the plants will be smaller, and the flowers as well, although they might not even be able to flower. The good news is that with more completion only the strongest Dahlia tubers will survive, and you will end up with fewer but healthier plants. The bad news is that this process can take several years and your Dahlias might not look so good for a while.
Just keep in mind that the bigger the Dahlia tuber clump is the more water and nutrients they need, oftentimes what tends to kill off an entire clump is not having access to either water or to nutrients. Overcrowded dahlia tubers are also prone to drying out, especially once they start flowering, so make sure to water them every day.
Thin And Weak Stems
Although not dividing Dahlia tubers usually means that there will be more sprouts in the spring, but this is not always a good thing. If you do not thin out the sprouts then the stem of the plants will be thin, weak, and leggy. This tends to happen because of the increased competition for sunlight, water, and nutrients. As long as the Dahlias have plenty of nutrients and water they will try to outgrow the other sprouts.
Dahlias have to be staked, but staking thin and leggy Dahlias that have weak stems will be difficult. Oftentimes even when staked these weak stems will simply snap under a light wind, especially once they start to flower. If you do not want to divide your Dahlias then make sure to at least thin out the sprouts, this was only a couple of them will grow but their stems will be a lot stronger if they do not have to compete for sunlight. If your Dahlias are starting to sprout in storage then check out my recent article Dahlia Tubers Sprouting In Storage ( Top 3 Reasons ).
Prone To Rotting
Usually what tends to kill Dahlia tubers is tuber rot which is a result of too much water. Dahlias that have never been divided will form larger clumps of tubers that need more water, but giving them more water increases the chance of one or two tubers sitting in water for so long that they eventually start to rot. Once a couple of Dahlia tubers start to rot it is only a matter of time until the entire clump dies off.
People who dig up their Dahlias every year will remove any rotten, damaged, or soft tubers this way only the healthy ones get replanted in the next season. As the older tubers start to die off they will increase the humidity in the soil, as the tubers contain a lot of water. If only a couple of tubers die off one at a time then this isn’t a big problem, but the larger the Dahlia clump is the more tubers will start to die off eventually.
Key Takeaways
- If you do not divide your Dahlias then they will grow more sprouts, although you will have to thin them out, or else they will become weak and leggy. If the Dahlias have not been divided in a long time then they can get overcrowded, which means smaller plants and fewer flowers due to the increased competition for water and nutrients. In addition to this, Dahlias that are not divided are prone to tuber rot, which can rot away even a large clump of Dahlia tubers in a matter of weeks.
- Dahlias that have never been divided will sooner or later get overcrowded which usually means smaller plants and fewer flowers.
- Dahlias that are not divided are prone to getting tuber rot.