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Dahlia vs. Zinnia (The Key Differences to Know)

Dahlia vs. Zinnia (The Key Differences to Know)

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If you’re looking for gorgeous and colorful flowers for your garden, then you might be drawn to both dahlias and zinnias. A dahlia and a zinnia will be similar in certain ways, but it’s important to know that they’re distinct.

Both of these flowers are members of the sunflower family, and their flowers have a similar look. They both produce blooms that are made of several smaller flowers that come together to form a large head.

This classic look leads some people to mistakenly think of zinnias and dahlias as being the same. There are important differences between the two that you should note.

Continue reading to learn more about the differences between dahlias and zinnias. This might help you to decide which of the two plants will be right for your garden.

The Flower Size Might Be Different

Variety of Dahlias
Variety of Dahlias

When looking at dahlias vs. zinnias, it’s important to know the differences between the two. One difference that you should note right away is that the flower sizes will be different.

Dahlias, in particular, have a wide range of different sizes. There are many varieties of both dahlias and zinnias, and some are going to be bigger or smaller than others.

Depending on the variety that you purchase, you’ll see that the sizes will change. Even the diameter of the flowers will differ.

Some might have a diameter of only one inch while others will be as large as fourteen inches. Zinnias have good size diversity as well, but you’ll typically only see zinnias with flower diameters as large as seven inches.

If you want the flowers of either a zinnia plant or a dahlia plant to be a specific size, then you’ll need to look at specific information about the variety that you’re purchasing. You should be able to learn about how large the blooms are on average.

Those looking for the biggest flowers might go for the larger varieties of dahlias. There are also large zinnia blooms to consider, but dahlias do have the potential to be larger due to the fact that there are dahlias out there with fourteen-inch diameters.

Different Flower Shapes

Multiple Zinnias
Multiple Zinnias

Although dahlias and zinnias might appear to be similar at first glance, you’ll notice that they have different flower shapes. Zinnia flowers are actually a bit more diverse in the types of shapes that they take.

You’ll find zinnia flowers that are dome-shaped, but there are also flowers that are circular. Dahlia flowers are a lot different because they will usually appear to be flatter and bigger.

There are some dahlia flowers that are almost ball-like, but they’re still much flatter than the zinnia flowers are. If you’re caring for both zinnias and dahlias, then you’ll see that the two have very distinct flowers even if they’re aesthetically similar when viewed at a distance.

You might be drawn to one flower type or the other depending on your preference. Both flowers are very beautiful, and this means that you can’t go wrong either way.

They Have Different Colors

Three Colorful Zinnias
Three Colorful Zinnias

You should also know that dahlias and zinnias have different colors. There are some colors that are shared between the two, but there are significant differences as well.

Dahlias produce blooms that are either yellow, purple, orange, pink, red, and some dark purple shades. Zinnia blooms will be either yellow, white, off-white, pink, lilac, pale green, gold, red, purple, and orange.

As you can see, zinnias produce a wider array of different colored blooms. The only colors not represented by zinnia blooms are blue, brown, and black.

If you want to have more color options, then going with zinnias might be best. Both produce flowers that are gorgeous and you’ll have many colors that can potentially bloom either way.

Height Differences

Tall Pom Pom Dahlia
Tall Pom Pom Dahlia

There are height differences to consider when looking at dahlias and zinnias as well. Zinnia plants will usually grow between six inches tall and fifty inches tall.

Dahlia plants have the potential to be quite a bit taller. These plants will usually be at least one foot high and some grow as tall as six feet.

If you purchase one of the taller varieties of dahlia plants, then you’re going to get very big flowers. These flowers will be substantially larger than any that zinnia plants can produce.

Anyone who is looking for the biggest blooms possible will be pleased with dahlia plants. This doesn’t mean that the zinnia plant isn’t also bold and beautiful in its own right, though.

Different USDA Zones

Both dahlia plants and zinnia plants will thrive in different environments. There is some overlap, but these two plants don’t have the same USDA zone recommendations.

Dahlia plants are meant to be grown in USDA zones 8 through 10. If you don’t live in those zones, then you’re not going to have good luck growing these flowers outside of a greenhouse environment.

Zinnia plants have a wider range of USDA zones that they can thrive in. You can grow zinnia plants in USDA zones 2 through 11.

That means that zinnias will thrive in the same zones as dahlia plants. However, dahlia plants can’t survive in the majority of the zones where zinnias will do well.

Which Is Better?

Planting a Dahlia

There isn’t really an answer to this question. Whether you will want to plant zinnias or dahlias in your garden will depend on what you’re looking for.

Dahlia plants are going to be taller and they have the potential to produce larger blooms. Zinnias are going to have a wider variety of colors.

Both of these plants are similar in many ways, but they have big differences, too. Even the flower shapes are quite distinct once you examine them up close.

Zinnias are going to be more practical to own for many people. They’re capable of thriving in USDA zones 2 through 11, and this makes it possible for them to be planted in many places where dahlias cannot survive.

Simply take all of this information and pick out the right flower for your garden bed. If you live in the right USDA zone, then you might even be able to plant both in your yard.

Final Thoughts

After reading the above information, you’ve been able to determine the differences between zinnias and dahlias. Both of these flowers are similar, but they’re different enough that you shouldn’t mistake them for being the same type of plant.

These are both flowers that are considered to be part of the sunflower family. They both produce colorful and pretty blooms, but the differences mostly end there.

Dahlia plants are much taller on average and they have the potential to produce very large flowers. Zinnias come in more colors, but they won’t be quite so large.

Zinnias are hardier than dahlias because they can thrive in more USDA zones. For many, zinnias will be a more practical choice simply for this reason.

Growing either of these beautiful plants will help to make your garden more aesthetically appealing. They can provide color to your yard and they’re both not too hard to take care of overall.

If you have friends who are confused about the differences between zinnias and dahlias, then you can tell them what you’ve learned. It might help them to better care for the plants so that they can continue to thrive and look stunning in their yards.