The tiny yellow dandelion flowers add color to any garden or prairie. However, not everybody likes these weed-like plants because they spread very easily. Nonetheless, there’s something fascinating and magical about how their yellow blooms become a puffy white.
Dandelions turn white as a sign that they have successfully pollinated and have moved on to the next stage of their life–seeding. The white fluff that replaces the flower contains hundreds of bristles called pappuses that fly with the wind and carry the seeds with them to start a new life cycle.
Let’s get into more detail about the science behind dandelions turning white. I’ll discuss how dandelions turn from yellow to white, how long the process takes, how to prevent the pappuses from spreading, and more.
How Do Dandelions Turn From Yellow to White?
To fully explain the science behind how and why dandelions turn white, we must start with the entire growth process of the weed. So, let’s get into the details of how a dandelion grows and matures.
Seed
Dandelions multiply through apomixis. This is an asexual process that allows plants to reproduce by spreading their seeds. This process makes the reproduction of dandelions quick and easy, as the seeds can spread naturally, even with a light breeze.
Once the dandelion seed reaches its new location, it will enter the soil and begin to form roots. Dandelion seeds work quickly to form roots that become very dense and strong.
So, when you see a dandelion growing, the roots are most likely already well established in the ground. It’s not rare to notice new growth within the same year.
Dandelions spread their seeds during their second phase of blooming. As we get further into the growth process of a dandelion, we will talk about how the seeds spread.
Cotyledons
As the seed of the dandelion begins to germinate, it will first emerge from the ground as two cotyledons. Cotyledons are the first leaves that appear from some plants, and they are used as a food source to help them grow stronger. This is how the dandelion gets the sunlight and other nutrients it needs to grow.
The cotyledons of dandelion contain important nutrients that they push into the weed roots, feeding them. As the cotyledons feed the roots of the dandelion, they will continue to grow downward in the soil, becoming stronger.
Eventually, the roots will be strong enough to absorb nutrients by themselves and grow true leaves. The two cotyledons help the dandelion grow its true leaves to replace them.
Cotyledons are small and barely noticeable unless you intentionally look for them. You probably won’t notice the dandelion growing at this stage. Instead, it is more likely you will notice them at the next stage when the true leaves come out.
True Leaves
Once the two cotyledons have provided enough nutrients for the dandelion roots to grow strong, the plant will begin to grow new leaves over top of the cotyledons. These are the real dandelion leaves, which will take over the photosynthetic and food-making functions of the plant.
Once the true leaves take over, you are more likely to begin noticing the dandelion. The true leaves are a light green color and can have a yellow tint to them. The leaves of the dandelion will form a circular pattern around the center in the form of a rosette. They can grow anywhere from 2-14 inches (5.1-35.6 cm) long.
The color of the leaves will darken as they grow. So, the darker the leaves, the closer the dandelion is to blooming. Once the rosette forms, the stalk is not far behind. The stalk will grow from the center of the circle of leaves.
The stalk typically grows up to 12 inches (30 cm) long and quickly produces a small bud that will eventually open as a yellow dandelion flower.
Blooming
Once the small bud at the tip of the stalk opens, you will notice a beautiful yellow dandelion. A dandelion has a composite flower with several yellow rays called florets. Each dandelion head can hold up to 200 small yellow florets.
At this stage, the dandelion plant is considered mature, and the reproduction process begins. As the dandelion reaches maturity, it develops a mix of male and female parts, allowing pollination to take place.
Dandelions can pollinate in two ways. The most common way is through the help of pollinators like bees that can transport the pollen from one flower to the ovule of another through their legs. This natural phenomenon allows cross-pollination among neighboring flowers and helps create future dandelion seeds.
Alternatively, dandelions can pollinate themselves by curling inward and dropping pollen down to the ovule.
Self-pollination can be important for the spreading and growth of dandelions because the blooms are not always open. Dandelions do not stay open after they bloom. Instead, they will open each morning and close each night.
Depending on the environment they are growing in, they can’t always rely on insects for the pollination process to occur. That’s where self-pollination plays an important role in the spread of dandelions.
When some buds remain closed after a few days of blooming, it’s a sign that the flowers have pollinated and are undergoing the next stage in their development.
Successful Pollination
When the dandelion completes the pollination process, the bud will close. This is normal behavior and is difficult to distinguish from the regular opening and closing of the bud that the plant does at night.
The main difference is that the bud will not open right away. Instead, each fertilized floret will produce a seed. When the floret produces a seed, that seed will form at the bottom of the floret.
As the seeds develop, they push the remaining bits of the florets to the top of the bud. Once all florets are at the top of the bud, the dandelion is ready to open. Right before it opens, the dandelion will allow the remaining parts of the florets that have gathered at the top to fall away.
The bud slowly dries up and the sepals gradually fall away. Eventually, a burst of white, feathery fluff breaks out of the bud. This fluff contains bristles or strands individually called a pappus.
The Now White Dandelion
Each pappus on the white fluff contains a seed. Because the pappupes are so light, the wind can easily blow them away from the plant. Taking the light seeds with them as they fly, the pappuses help spread them around.
As discussed, the seeds can easily grow in other places where they land, and the cycle continues. Other seeds that are buried too deep in the soil may remain dormant but viable for up to five years.
After the wind or any other force removes each pappus from the dandelion, the life cycle is complete. However, this does not mean the end of the dandelion after reseeding. They have very strong root regenerative properties that allow them to regrow after the process is complete.
How Long Does It Take for a Dandelion To Turn White?
It takes about a month for a dandelion bud to bloom yellow and eventually turn white. The buds need about ten days to generate energy and release the yellow flowers that bloom for about a week. After that, it can take around 8-12 days for the seeds to ripen and come out as white pappus.
Overall, the plant takes approximately 90 days to grow from seed to a mature plant with flowers. Here’s a breakdown of the stages:
- 10-14 days: seed to germination
- 40-50 days: root establishment and shoot growth
- 10-14 days: buds to flowers
- 7-10 days: blooming period
- 8-12 days: flowers to seeds
After the dandelion blooms, you will only see it for about a week before it begins the pollination process that turns it white.
The weed will remain closed for several days while the seeds move to the top of the florets and leave behind the white pappus. This means that it can be difficult to tell what stage of growth the dandelion is in when closed.
Overall, it does not take a long time to see the white dandelion fluff that we all recognize. Once you see the yellow flower, you only have a couple of weeks at most before it turns white.
If you want some more information about how and why dandelions are able to grow so fast, check out my article on that topic: This Is Why Dandelions Grow So Fast
How to Prevent Dandelion Pappuses from Spreading
It’s important to note that dandelion seeds generally take less than two weeks to germinate. Mature dandelions are also tolerant to nutrient-poor and compacted soil, so they can still reproduce.
Another reason that dandelions are so difficult to stop from spreading is that they still grow in colder weather. The growth process slows down when it is cold, but it doesn’t stop. That said, the cold weather will not help kill these weeds. Dandelions will simply remain less active until the weather gets warm again and they get ready to bloom.
Moreover, dandelion seeds can remain in the ground for several years and germinate when the conditions become favorable. So don’t be surprised if you see new dandelion seedlings growing out of your soil a few years after you’ve cleared your garden of matured ones.
That’s why you’d want to prevent those pappuses from spreading. Overall, there are several ways to prevent dandelions from pollinating or reproducing:
- Remove the unwanted dandelions and their roots completely. Dandelions can regenerate from the roots, making them rather challenging to control. Pulling them out along with their roots will prevent them from growing back.
- Keep removing the buds that have started to dry up. That’s a sign that the seeds and pappuses are starting to develop inside, and it’s only a matter of time before they break out from the bud.
- Collect the pappuses as soon as they emerge from the buds. Yellow dandelion flowers add beauty to any garden, so you may become hesitant to remove the buds so soon. That should be fine. However, be vigilant for the moment the pappuses come out and collect them as quickly as possible.
- Pull out the newly germinated dandelions as soon as you spot them. If some pappuses managed to spread before you could get to them, you can watch out for new growth. As mentioned, dandelions take less than 14 days to germinate. You can check the ground for new shoots as early as ten days after the first pappuses emerged.
How Often Do Dandelions Bloom?
Dandelions can bloom twice per year. They tend to bloom once in early spring and again in the fall. This is because they grow and mature very quickly, which is why they spread so quickly.
The composition of a dandelion allows it to bloom quickly and often. Once the roots have developed, the rest of the growing process comes quickly and easily. Part of the reason for this is that the bloom sits on a hollow stalk instead of a stem. This makes it flimsy but easier for the weed to replace.
There doesn’t need to be a full year between blooms for dandelions, as the roots work quickly to grow another bloom. You can expect the first bloom from a dandelion in early spring, particularly from May to June. These are the most potent months for the growth and blooming of dandelions.
The second bloom won’t occur until fall, around September or October, just before it gets too cold. Late fall blooms typically aren’t as strong as spring blooms, but they will still bloom and pollinate during this period.
Dandelions can bloom twice per year for as long as they survive. Undisturbed, they can survive for up to about 13 years. This means that over its lifespan, a healthy, undisturbed dandelion can bloom over 20 times before it dies off.
This means that one dandelion left alone can bring about many more dandelions around it because of flexible pollination options and the prolific spreading process.
This is why it is so important to remove unwanted dandelions and do it carefully so they don’t come back, especially if you have limited garden space. As mentioned, they can spread their seeds very easily, and these seeds can grow quickly.
You need to remove the buds after pollination or the pappuses as soon as they come out to control the plant’s spread. For more information, check out my guide on how to control dandelions: How to Prevent Dandelions from Spreading: Complete Guide
Will Every Dandelion Flower Pollinate?
Every dandelion that can reach maturity will pollinate unless there’s human intervention. Insects are helpful but unnecessary for pollination because of a dandelion’s ability to self-pollinate. You should control your dandelions if you don’t want them to spread.
If left undisturbed, every dandelion will pollinate. This is what makes them so invasive and sometimes frustrating to deal with. Even one dandelion plant left alone can reproduce into many by the end of the year.
Are Dandelions Bad for Allergies When They Turn White?
White dandelions can cause issues for those who have allergies but only if the seeds reach them. Most of the time, they are not a problem because the wind keeps the pappuses low to the ground. However, picking one up can cause an allergic reaction to people with hypersensitivity.
If you suffer from allergies, like many others, you probably wonder what sets them off. When looking at white dandelions, you may think that they are the cause behind your constant sneezing during spring or fall.
While they can be behind your allergy problems, it isn’t very likely they are the only culprit. Seeing a field of white dandelions can cause concern for anyone with allergies, but just one lone dandelion will rarely cause any type of reaction.
So, unless your yard or garden is overrun with them, they won’t affect you much as long as you don’t pick them up.
Dandelion pappuses are only likely to affect you as they become airborne. That may sound alarming, as they’re light and easily carried off by gentle winds. Depending on the direction of the wind, they may or may not get to you.
Wearing a mask during the blooming season can help prevent allergic reactions. Remember that dandelions are not the only source of allergic reactions. Several other flowers have pollens that can trigger more severe reactions.
Final Thoughts
While dandelion flowers start off as the beautiful yellow blooms we all know, it doesn’t take long for them to turn white and fluffy. This is the plant’s way of showing its transition from flowers to seed.
While they are pretty and fun for children to play with during this stage, this is also when the seeds spread to other places. If you don’t want more dandelions in your garden, you can collect these white fluffs and put them in a bag before they spread elsewhere.
