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Dahlias are one of the superstars of the summer garden. They provide stunning visual interest with their colorful blooms, and they’re beautiful cut flowers.

However, in order for your dahlias to thrive and produce the best blooms, you’ll need to do a bit of maintenance. Topping and disbudding are two essential—and easy!—gardening tasks that will help your dahlias create larger, higher-quality blossoms. To help you get started, we spoke with dahlia experts about how you can properly groom these beautiful flowers—along with a few common mistakes you should always avoid.

What Is It?

Topping and disbudding are each very important. However, they’re very different methods, and should be performed at different times during the growing season. 

Topping

Topping is also called pinching or pinching out, and it’s performed early in the season when the flower is about 12 to 14 inches tall.

“Topping removes the central growth tip of the plant,” says dahlia breeder Kristine Albrecht. This is important because the central growth tip produces hormones that suppress branching in the axillary buds lower down in the plant. Removing the growth tip reduces the hormones, allowing the plant to produce additional lateral branches, making it bushier and more productive.

Disbudding

Disbudding is done later in the season, when the plants are actively producing buds.

“On a typical dahlia stem, you’ll see one central bud, flanked by two smaller, lateral buds,” says horticulturist Kate Walz. “Disbudding is the practice of removing the smaller side buds, which enables the plant to put all its energy into the central flower.”

Benefits of Topping

Topping your dahlias early in the growing season can make a big difference in the plant’s future appearance.

“Removing this central stem encourages the plant to branch out, creating more flowering stems,” says Walz. “Although this process will delay the blooming time slightly, overall, it will give the plant better structure—and ultimately more flowers.”

Benefits of Disbudding

“Disbudding doesn’t affect the shape or growth pattern of the plant,” says Albrecht. However, this method still plays an important role.

Dahlia plants typically produce one main bud at each bud location, along with two secondary buds. “The main bud is further along in the blooming process and will bloom first. If that bloom is cut from the plant, the secondary buds will never bloom,” she adds. “They’re too far behind in the maturity cycle.”

By removing the two secondary buds early on, the dahlia puts all of its energy into the main bud, making it a bigger, more beautiful bloom. That isn’t the only benefit of disbudding. It can also help preserve the plant’s energy, which it can put into tuber production. 

Another key benefit: “[Disbudding] gets growers to routinely look closely at their plants. When disbudding, growers often see pest or nutrient issues that they wouldn’t have seen [otherwise,]” adds Albrecht.

How to Do It 

Topping and disbudding are very easy processes that won’t take up too much of your time. Here’s everything you need to know to successfully perform both methods.

Topping

Topping is as simple as pinching off the tiny tip of the plant’s main stem.

The best time to top is when young plants have four to five leaf junctions and are 12 to 14 inches high. “At that age, the plants don’t have a hollow stem,” says Albrecht. “The growth bud is easily removed by snapping it off with your fingers. The wound heals in a few days.”

Disbudding

When dahlias set buds, each bud location has one central bud and two smaller lateral buds.

Disbudding is the process of removing those lateral buds. You can do this with a clean pair of pruners, or you can bend the small buds with your fingers so they easily break off. “Proper disbudding involves snapping off the buds, not pinching them,” says Albrecht. 

Common Mistakes

Despite everyone’s best efforts, it’s not unusual to make mistakes when topping or disbudding dahlias. Here are a few that you should avoid making.

Topping Multiple Times

Topping is a singular moment in the plant’s growth that will last for its lifetime.

“The most common mistake people make is [topping] it more than once,” says Albrecht. Once the original terminal bud has been removed, the plant will branch for the rest of its life cycle. “People new to dahlias often top a plant and then continue to top it as the plant produces more lateral branches,” she warns. “That will reduce the plant’s ability to produce copious blooms.”

Disbudding Too Late

“Once the buds start to open, the energy from the plant to make the flowers has already been spent,” says Walz. Be sure to disbud when the lateral buds are still quite small. Disbudding too late can leave a large scar.

Topping Too Early

It’s important not to pinch the plant too low, even if it’s early in the season.

“Removing too much of the plant (leaving only one to two sets of leaves) weakens [it] and delays its growth as it tries to recover,” says Walz. The sweet spot for topping is just above the third or fourth set of leaves. 

Topping Too Late

“[Another] common mistake is that growers wait too long before removing the growth bud,” says Albrecht. “Growers who wait until the plant is 3 to 4 feet high must use tools to remove the growth bud. By then, the stem is hollow, and will collect water that could rot the tubers—or provide a habitat for earwigs.”

Using Your Fingernails

When disbudding, remember to use pruners—or just carefully snap the buds. “Some growers use their fingernails to pinch off the wing buds,” says Albrecht. “This gets the plant’s juices on the fingers, and when they pinch on the next plant, they could spread viruses or diseases.”

Using Dirty Tools

“For both pinching and disbudding, it’s crucial to ensure you have clean, sharp pruners,” says Walz. “Dirty or dull tools can introduce disease or cause ragged wounds that don’t heal well—and they may even compromise the entire plant.”

For nearly a century, scientists have been puzzling over fossils from a strange and robust-looking distant relative of early humans: Paranthropus robustus. It walked upright, and was built for heavy chewing with relatively massive jaws, and huge teeth with thick dental enamel. It’s thought to have lived between 2.25 million and 1.7 million years ago.

Humans today have a diverse array of hominin distant relatives and ancestors from millions of years ago. The South African fossil record ranges from early hominins such as Australopithecus prometheus, A. africanus (Taung child), A. sediba and P. robustus, to early members of the genus Homo (H. erectus/ergaster, H. habilis), to later hominins such as H. naledi and Homo sapiens (humans).

Fossils show how these early relatives evolved from as far back as A. africanus, 3.67 million years ago. They also document milestones in evolution, including the transition to walking on two legs, tool making and increased brain development. Ultimately, our species – Homo sapiens – appeared in South Africa 153,000 years ago.

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Palaeontology: a way of reaching into the past to build lessons for the present

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Fossils of P. robustus were first discovered in South Africa in 1938. But crucial questions remained. How much variation was there within the species? Were the size differences related to sex, or did they reflect the presence of multiple species? How was P. robustus related to the other hominins and early Homo? And what, genetically, made it distinct?

Until now, answers to these questions have been elusive. As a team of African and European molecular science, chemistry and palaeoanthropology researchers, we wanted to find answers but we couldn’t use ancient DNA to help us. Ancient DNA has been a game-changer in studying later hominins like Neanderthals and Denisovans but it doesn’t survive well in Africa’s climate because of its simple structure.

We experienced a breakthrough when we decided to use palaeoproteomics – the analysis of ancient proteins. We extracted these from the enamel of the 2-million-year-old teeth of four P. robustus fossils from Swartkrans Cave in South Africa’s Cradle of Humankind.

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Luckily, proteins that are millions of years old preserve well because they stick to teeth and bones and are not affected by the warm weather. One of these proteins tells us the biological sex of the fossils. This is how we found that two of the individuals were male and two were female.

These findings open a new window into human evolution – one that could reshape how we interpret diversity in our early ancestors by providing some of the oldest human genetic data from Africa. From there, we can understand more about the relationships between the individuals and potentially even whether the fossils come from different species.

More than one kind of Paranthropus?

The protein sequences also revealed other subtle but potentially significant genetic differences. One standout difference was found in a gene which makes enamelin, a critical enamel-forming protein. We found that two of the individuals shared an amino acid with modern and early humans, chimpanzees and gorillas. The other two had an amino acid that among African great apes is, so far, unique to Paranthropus.

What’s even more interesting is that one of the individuals had both the distinct amino acids. This is the first documented time we can show heterozygosity (a state of having two different versions of a gene) in proteins that are 2 million years old.

When studying proteins, specific mutations are thought to indicate different species. We were quite surprised to discover that what we initially thought was a mutation unique to Paranthropus robustus was actually variable within that group – some individuals had it while others did not. Again, this was the first time anyone had observed a protein mutation in ancient proteins (these mutations are usually observed in ancient DNA).

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When did our ancestors start to eat meat regularly? Fossilised teeth get us closer to the answer

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We realised that instead of seeing a single, variable species, we might be looking at a complex evolutionary puzzle of individuals with different ancestries. This shows that combining analyses of morphology (the study of the form and structure of organisms) and the study of ancient proteins, we can create a clearer evolutionary picture of the relationships among these early hominin individuals.

However, to confirm that P. robustus fossils have different ancestry, we will need to take samples of tooth enamel protein from more of their teeth. To do this, we plan to sustainably sample more P. robustus from other sites in South Africa where they’ve been found.

Preserving Africa’s fossil heritage

Our team was careful to balance scientific innovation with the need to protect irreplaceable heritage. Fossils were sampled minimally, and all work followed South African regulations. We also involved local laboratories in the analysis. Many of the authors were from the African continent. They were instrumental in guiding the research agenda and approach from the early stages of the project.

Doing this kind of high-end science on African fossils in Africa is an important step towards transformation and decolonisation of palaeontology. It builds local capacity and ensures that discoveries benefit the regions from which the fossils come.

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By combining data on molecules and morphology, our study offers a blueprint for future research – one that could clarify whether early hominins were more or less diverse than we’ve known.

For now, the Paranthropus puzzle just got a little more complex – and a lot more exciting. As palaeoproteomic techniques improve and more fossils are analysed, we can expect more surprises from our ancient relatives.

(Jesper V. Olsen, Rebecca R. Ackermann and Enrico Cappellini were also the principal investigators on this project.)

A recent study published in the Monthly Notices of the Royal Astronomical Society reveals the discovery of the most distant and most pristine fossil galaxy ever found, KiDS J0842+0059, located about 3 billion light-years away from Earth. This galaxy, which has remained largely unchanged for an astonishing 7 billion years, provides a unique opportunity to study the early universe and the processes that shaped the formation of massive galaxies.

The discovery was made possible by the work of a team led by the Italian National Institute for Astrophysics (INAF), who used cutting-edge tools like the Large Binocular Telescope in Arizona. The galaxy is not only the most distant fossil galaxy discovered so far but also the first of its kind observed beyond the local universe, a region only about 1 billion light-years from Earth. This find expands the frontiers of what we know about the early cosmos.

What Are Fossil Galaxies and Why Are They So Important?

Fossil galaxies are rare objects that provide a glimpse into a universe long past. They are galaxies that, unlike most others, escaped the typical evolutionary processes such as mergers and active star formation. After an initial, rapid burst of star formation, fossil galaxies stopped evolving. For reasons not yet fully understood, they remained undisturbed for billions of years.

“Relic galaxies, just by chance, did not merge with any other galaxy, remaining more or less intact through time,” explained Crescenzo Tortora, a researcher at INAF and lead author of the study. “These objects are very rare because, as time goes on, the probability to merge with another galaxy naturally increases.”

What makes fossil galaxies particularly fascinating is that they essentially serve as time capsules, preserving an image of the universe in its infancy. Studying these galaxies allows scientists to understand how galaxies first formed and how star formation occurred in the early stages of the universe. While most galaxies grow larger and merge with others, these fossil galaxies avoided such chaos, providing clues about the original conditions that led to their formation.

The Early Stages of Fossil Galaxy Formation

Fossil galaxies are born in two distinct phases. The first phase is marked by a sudden burst of star formation that is quick and violent. This intense period results in a galaxy that is compact, dense, and small — essentially the “progenitor” of the fossil galaxy.

“First, there’s an early burst of star formation, a very quick and violent activity,” said Chiara Spiniello, co-author of the study and researcher at the University of Oxford. “We end up having something very compact and small, the progenitor of this relic.”

The second phase is where the typical galaxy evolution takes place: galaxies grow larger by interacting with one another, merging and evolving their shapes and star populations. Fossil galaxies, however, missed this phase entirely. They formed almost entirely during the first star formation burst, and, as a result, they have a unique structure, with their mass nearly fully established in that first phase.

Why Are Fossil Galaxies So Dense and Unchanging?

One of the most defining features of fossil galaxies is their remarkable density and lack of star formation. Unlike our own Milky Way, which is still actively forming new stars, fossil galaxies have stopped producing new stars altogether. They contain billions of stars, each as massive as the sun, but they are static, doing “essentially nothing.”

“They contain billions of stars as massive as the sun and they are not forming any new stars — they’re doing essentially nothing, and they are the fossil records of the very ancient universe,” said Spiniello. “They formed when the universe was really, really young. And then, for some reasons that we honestly don’t understand yet, they did not interact. They didn’t merge with other systems. They evolved undisturbed, and they remained as they were.”

This feature is what makes fossil galaxies such valuable objects of study. They have avoided the chaotic processes that most other massive galaxies have gone through, providing astronomers with a direct link to the conditions of the universe billions of years ago.

The Role of Supermassive Black Holes in Fossil Galaxies

Another aspect of fossil galaxies that remains a mystery is why they stopped forming stars so abruptly. Michele Cappellari, a professor of astrophysics at the University of Oxford, believes that feedback from supermassive black holes may be responsible for halting star formation in these galaxies. Supermassive black holes, found at the center of most large galaxies, can emit powerful winds that either expel or heat the gas within a galaxy, preventing the formation of new stars.

“As ‘living fossils,’ they have avoided the chaotic mergers and growth that most other massive galaxies have experienced. Studying them allows us to reconstruct the conditions of the universe in its infancy and understand the initial bursts of star formation,” said Cappellari. “Evidence from both local and distant observations suggests that feedback from supermassive black holes may be responsible. These black holes can produce powerful winds that expel or heat the gas in a galaxy, preventing further star formation. However, this remains an active area of research.”

What Makes KiDS J0842+0059 So Special?

KiDS J0842+0059 stands out even among other fossil galaxies for its extreme nature. It is what scientists call an “extreme relic” because almost all of its stars (99.5%) were formed during the initial starburst phase of the galaxy’s creation. After this burst, the galaxy has remained inactive, making it the perfect example of a fossil galaxy.

“This is what we call an extreme relic,” said Spiniello. “Because almost all, or 99.5% of its stars were formed incredibly early on in cosmic time, and the galaxy did absolutely nothing thereafter.”

This galaxy’s status as an extreme relic has important implications for our understanding of galaxy formation. It provides valuable information about the early universe and could help scientists understand why some galaxies evolve while others remain static.

The Future of Fossil Galaxy Research

The confirmation of KiDS J0842+0059 as a distant fossil galaxy is a major milestone in the study of the universe’s ancient past. As technology continues to advance, astronomers expect to discover more fossil galaxies, particularly with the help of telescopes like James Webb and Euclid, both of which are designed to observe distant objects in the universe. These instruments will make it easier to find and study these rare and mysterious objects, helping scientists further unravel the mysteries of the early universe.

“There must be something that prevents them from merging, but without knowing what, we cannot really predict what’s going to happen in the future,” said Spiniello, pointing out that while fossil galaxies have avoided mergers for billions of years, their future remains uncertain.

The Rarity of Fossil Galaxies

The rarity of fossil galaxies makes their study particularly important, but also challenging. The number of known fossil galaxies is very small, and it’s difficult to know exactly how rare they are. Sébastien Comerón, an astronomer at the Universidad de La Laguna in Spain, emphasized the rarity and mystery of these objects.

“Relic galaxies are mysterious,” Comerón said. “The fact that a few galaxies are nowadays untouched relics of the first large galaxies needs an explanation.”

The discovery of KiDS J0842+0059 gives scientists hope that more fossil galaxies can be identified and studied, offering a unique window into the early universe. By studying these ancient objects, astronomers may uncover vital clues about the birth of galaxies, star formation, and the evolution of the cosmos itself.