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How to Grow Beautiful Zinnia Flowers

Zinnia flowers are the perfect flower to grow for both beginner and experienced gardeners alike. They are fast-growing, easy, colorful flowers that attract pollinators and are a welcome addition to any garden! Learn how to grow zinnia flowers.

Zinnia flowers & my tips for how to grow and care for them

Zinnia flowers were one of the first things I ever grew from seed. My mom recommended them to me as a beginner because they are so easy. And she was right—they are a total confidence booster for new gardeners.

But they are also perfect for experienced gardeners. They grow quickly, are easy to care for, aren’t terribly vulnerable to pests, and provide gorgeous color in your garden from spring up until the first frost. Oh—and they make fantastic cut flowers and pollinators love them.

Where are zinnias from?

The full name for the zinnia flowers we know and love is zinnia elegans. It is an annual plant grown for its flowers. Native to Mexico, it is grown worldwide and has even been naturalized in locations through North, Central, and South America; the West Indies, Australia, and Italy. 

zinnia elegans growing in a garden

Table of contents

This is a big post, so I’ve created a table of contents to help organize things. If there is something specific you are looking for in this post, see the list below. If you just want to browse all of it and learn about growing zinnias, that’s great too!

  1. Zinnia history
  2. What are the different types of zinnias?
  3. How tall do zinnias get?
  4. Are zinnias sun or shade?
  5. What month do you plant zinnias?
  6. Can I just scatter zinnia seeds?
  7. Where is the best place to plant zinnias?
  8. Do zinnias do well in pots?
  9. How quickly do zinnias grow?
  10. Do zinnias bloom all summer?
  11. How long do zinnia flowers last?
  12. Will zinnias rebloom after cutting?
  13. Do zinnia come back every year?
  14. How to harvest seeds from zinnia flowers
  15. Do zinnias attract bees?
  16. Do zinnia flowers attract butterflies?
  17. Are zinnia flowers poisonous to dogs?
  18. What are the white powdery spots on my zinnias?
  19. How do I keep zinnias from falling over?
zinnia elegans growing in a garden
giant purple zinnia

What are the different types of zinnias?

According to the University of Wisconsin-Madison, there are 13 different species of the zinnia genus. However, that doesn’t mean there are only 13 different species of zinnias. There are A LOT of zinnias.

One different species of zinnia might have a bunch of different varieties, cultivars, and hybrid types. Flowers on zinnia plants can be single or double, and they can also have a variety of different shapes and sizes.

Here are a few different more common zinnia types you’ll likely encounter:

  • Zinnia elegans, the classic—it is tall and upright with wide leaves and large flowers
  • Zinnia angustifolia—a smaller, bushier variety that produces orange, yellow, and white flowers
  • Profusion zinnias—I fell in love with these last summer! They are compact but spread nicely about a foot wide. The colors can be pink, red, orange, and more.
  • Zahara zinnias—these disease-resistant zinnias have large flowers in a lot of colors. Some even produce double blooms.
bright pink profusion zinnias
polar bear zinnia

How tall do zinnias get?

As you might imagine, the different types of zinnias can have very different growth patterns. The more common zinnia elegans variety can grow to be up to 3 feet high and 1-2 feet wide (depending on pruning). 

These types of zinnias make a great choice for the back of a garden. Don’t make the same mistake I’ve made and plant them along the border of a garden (unless there’s something taller or nothing behind them!). 

Other smaller varieties of zinnia like profusion zinnias don’t even reach 1 foot tall. Instead, they spread a bit more. I have some profusion zinnias growing in my front beds—and they are right at the front with other plants behind them.

When you purchase your zinnia seeds or plants, just look on the label to see exactly what type you’re buying. It will tell you how large they’ll grow, so plant accordingly.

multicolored profusion zinnias

Are zinnias sun or shade?

Zinnias are full sun plants—that means 6+ hours of sun per day for the best blooms. However, I should note that I planted profusion zinnias in my front garden, which is more of a morning sun space. They went absolutely nuts all spring, summer, and early fall!

What month do you plant zinnias?

Zinnias are sensitive to frost. Don’t plant them in the ground until your last frost date has passed (Google to find yours since they are different everywhere).

You can get a jump start on your seeds indoors. Simply pop a seed or two into a small cup with soil. Give the seeds plenty of sun; consider a sunny window or a grow light with a heat lamp.

Then, when the plants are large enough to be transplanted and your last frost date has passed, move them to the garden. This is what I did this last summer.

bright pink and orange profusion zinnias

Can I just scatter zinnia seeds?

However, you can also just scatter your zinnia seeds! I’ve done this in the past. If you do this, just make sure you space them out according to the variety you’re growing. You can put more seeds than you need, though.

Then, once they sprout, just thin them out to adhere to the required spacing. This way, you won’t have any large gaps if a seed or two fails to germinate.

When you do scatter them, simply stick your finger down into the soil an inch or so and drop the seed. Then cover. Or scatter them and then cover with an inch or two of soil. Keep the soil moist for a few days.

zinnia varieties growing in a garden

Where is the best place to plant zinnias?

As mentioned previously, look for a spot with full sun. You also want to make sure the soil your plant is in is well-draining. We have a very dense, rocky, clay-like soil where I live.

Therefore, I ammend the soil with leaf compost mixed in when I plant in the ground. This gives it plenty of nutrients and a looser substrate to grow in. 

If you’re planting zinnias in containers, you can use any well-draining soil labeled as designed for “container gardening.” I did this for the profusion zinnias I planted in a pot last summer, and they were very happy!

Do zinnias do well in pots?

Speaking of, zinnias can do quite well in pots. I would recommend planting only the smaller varieties in pots. The taller varieties like zinnia elegans can get quite top heavy, and a larger root system anchored in the ground can help.

However, I have planted taller zinnias in large pots before, and it just required some pruning to keep things looking nice. Also make sure to monitor the soil moisture since the water evaporates faster in pots.

light pink zinnia flowers

How quickly do zinnias grow?

Zinnias grow quite quickly. If you start the seeds indoors, you should notice that your plants sprout in only 1-2 weeks. It will be a number of weeks to a month or so before you see your first flowers.

Do zinnias bloom all summer?

Yes, zinnias bloom all summer. They will likely begin blooming in the late spring. In my experience, the plants really take off around late June. 

Mine have exploded in size and flower production around then and continue to do so right up until the first frost. I’ve found that the shorter varieties hold up the best, though—likely because they are less vulnerable to powdery mildew. 

For more gardening, see my tips for How to Plant a Garden From Scratch and my post on How to Plant Tulips!

bright pink profusion zinnias

How long do zinnia flowers last?

While the plants themselves last up until the first frost, the individual zinnia flowers do not last that long. You’ll notice that some of the flowers begin to dry, brown, and die off about midway through summer.

This is okay. As long as the plant overall looks healthy and you’re keeping the soil evenly moist, it isn’t cause for concern. Simply prune off the unsightly stems and flowers—consider this deadheading.

You’ll likely notice more dying flowers as the season progresses. In early September, I did a large pruning of my taller zinnias. The smaller profusion plants required very little pruning all season.

drying zinnia flower

Will zinnias rebloom after cutting?

Yes! Don’t shy away from cutting your zinnias to make arrangements. When you cut your zinnia flowers at the stem, the plant will respond by sending out a new stem that will produce a flower.

Cutting the flowers can also help to encourage fullness. I generally cut about midway down the stem to the most recent growth point to prevent the plant from getting too leggy.

cut flowers in a vase

Do zinnia come back every year?

Zinnias are annuals, which means that they must be replanted every year. However, as the flowers die off, they will drop their seeds. Depending on your climate, it’s entirely possible—likely, even—that the seeds will resprout in the spring.

That’s right—the seeds will live through the winter and nature will pick back up where she left off in the spring when temperatures start to rise. If you don’t want your zinnias to spread, deadheading the dying flower heads helps.

Toward the end of the season when the flowers begin to decline much faster, you can also harvest zinnia seeds to plant for next year. I love harvesting seeds because, although you don’t really save that much money, it’s neat thinking about the plant continuing next year.

orange zinnia

How to harvest seeds from zinnia flowers

I have a whole post on how to harvest seeds from zinnia flowers and did a quick YouTube video showing the steps as well. However, here’s a quick overview of the process:

  1. Wait until the flower dries completely; there should be no color left, and it should be literally crumbling to the touch.
  2. Crumble the flower heads onto a paper towel and pick out the seeds; the seeds are the little pieces that look like arrowheads.
  3. Let dry for another 24 hours or so and then store in a plastic baggie or paper bag for next year.
dried zinnia flowers
dried zinnia flowers
harvesting zinnia seeds
zinnia seeds harvested from a flower

Do zinnias attract bees?

Yes! Zinnias attract many different types of beneficial bees. However, they prefer the larger varieties. I have seen countless bees on my elegans zinnias. Zinnias can also attract hummingbirds.

Do zinnia flowers attract butterflies?

Zinnias are also a wonderful addition to a butterfly garden. Monarchs and swallowtails love them. Check out the picture below I got on one of the zinnias in my mom’s backyard. I couldn’t believe my luck!

Keep in mind, though, that smaller or more compact zinnia types are not nearly as attractive to butterflies. They prefer the larger flowers with larger areas to feed on; see this list for varieties butterflies are more likely to visit.

butterfly on a red zinnia

Are zinnia flowers poisonous to dogs?

If you have pets, you may be wondering if zinnias are toxic to animals. According to the ASPCA, zinnia flowers are not toxic to dogs, cats, and horses.

spring garden
large light pink zinnia elegans plant

What are the white powdery spots on my zinnias?

This is powdery mildew. It is a common disease among many plants, not just zinnias. It shows itself as white to gray powdery spots on the plant’s leaves—occasionally on the stems and flowers, too.

It might not look great, but if it’s only a bit of powdery mildew, it isn’t a huge cause for concern. Zinnia plants can grow happily with powdery mildew. It just doesn’t look great.

But what is it? Remember, zinnia plants are from hot, dry climates. They don’t do well with excessive moisture—whether it’s from humid air or too much rain. And we can get both of those in our Maryland summers.

Here are a few things you can do to prevent or control powdery mildew:

  • Good air circulation can help to prevent powdery mildew infestations. Don’t plany your zinnias too close together, and consider pruning if they are really going bonkers growing.
  • Water the base of the plant, not the leaves; water in the morning so the hot summer sun can quickly dry out the leaves.
  • Choose varieties that are resistant to powdery mildew like zahara zinnias and profusion zinnias.
powdery mildew on a zinnia elegans
powdery mildew on a zinnia elegans

How do I keep zinnias from falling over?

The taller varieties of zinnias will generally grow strong enough to support themselves. However, if you’re growing a large number of flowers in a cut flower garden, you may choose to add some support.

You can use a simple bamboo stake and some twine to prop a plant up. Or you can use cut flower support cages or netting. You can see some wire concrete remesh used as a trellis in the photo below—something like that could work quite well horizontally attached to stakes.

zinnias and other plants in a garden

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