How to Grow Zinnias - The secrets to keeping vibrant blooms all summer


Zinnias are one of the most rewarding flowers to grow. They germinate quickly and can be sown directly outside or started indoors. Zinnias seem determined to bloom no matter what, and the more you cut them, the more they grow. Learn the simple techniques to grow this beautiful flower and enjoy vibrant blooms all summer. 

bouquet of pink zinnia flowers

Why Zinnias are our favorite flower. And why they'll soon be your favorite.

At Sow Right Seeds, we love zinnia flowers for several reasons.

  • Zinnias are incredibly easy to grow. You'll appreciate their quick germination.

  • They come in a range of colorful, show-stopping blooms for your garden. Their vibrant colors will bring a smile to your face.

  • They attract pollinators. Spend a relaxing summer day watching all the butterflies and hummingbirds appreciate your zinnia flowers.

  • Zinnias bloom continuously all summer and into fall until the frost kills them off. You won't have to spend time rearranging your flower garden.

  • They bloom profusely. Cut as many blossoms as you want to share with your friends. The more you cut them, the more they grow.

How to Grow Zinnias From Seed

How to plant zinnia seeds

Zinnia seeds are easy to plant directly in the garden. 

Once the air and soil temperature are at 70º, seeds can be planted outdoors.

Choose a sunny location with nutrient-rich soil that drains well.

Plant zinnia seeds at a depth of 1/4”. 

Space seeds at least 6” apart and up to 18” depending on the variety.

Water the seeds, keeping them moist until they germinate in 7 to 10 days.

This Zinnia Starter Kit comes with everything you need to start your zinnia flower garden. It’s made from 100% natural and compostable materials. It also makes a perfect gift for all your gardening friends. 

Kit includes: 5 fiber planting pots, 5 expanding soil discs, 5 wooden plant markers, and 1 large packet of California Giants Zinnia seeds.

How to start zinnias indoors

For earlier blossoms, zinnia seeds can be started indoors. 

Start seeds indoors 5 to 7 weeks before the last spring frost date. 

When seedlings are several inches high and have 3 to 4 true leaves, it will be time to start hardening them off so they are ready for outdoor conditions.

After all danger of frost has passed, transplant zinnia seedlings to a sunny location with enriched, moist soil.

bright pink zinnia flower

The secrets to vibrant zinnia blooms all summer long

Zinnias love to produce flowers, so getting them to bloom all summer is relatively easy. Getting the water, soil, sun, and cutting right will ensure continuous summer colors. 

Zinnias need warm temperatures and full sun. Don't plant them outside until the temperatures are above 70º F, and make sure they receive a full day of sunlight. 

Although zinnia plants can tolerate dry conditions and poor soil, planting your zinnias in nutrient-rich soil that drains well will result in better flowering.

To keep zinnias blooming, cut off flowers regularly. It may seem harsh to keep cutting, but zinnias love to share. Clip the stem just above a leaf or bud node, and new branches will emerge.

Don't be afraid to do this often so that the plants keep producing more flowers.

Succession planting will also ensure zinnia blossoms all summer long. Plant new zinnia seeds every 2 to 3 weeks to have new plants coming up when others are done growing. 

Zinnias come in a variety of bright colors and even Polar Bear white. Growing a mix of bright-colored Zinnias is a visual joy and will attract local pollinators. With different varieties and colors to choose from, you can have a field of mixed colors or planned sections of all the same color.

Some varieties have a single row of petals, while others are as fluffy as a pompom. Zinnias can grow 4 feet tall, but dwarf varieties, like Thumbelina, will be shorter. Blooms can be 3" wide and up to 5" for California Giants

monarch butterfly on zinnia

Zinnias for pollinators

Beyond their beauty, zinnias are a beneficial flower in vegetable gardens because they attract pollinators so effectively. Butterflies, bees, and even hummingbirds are attracted to the bright colors and readily available nectar. Planting zinnias will increase the biodiversity in your yard and create a healthy habitat for beneficial pollinators.

pile of zinnia blossoms

Zinnia FAQ

Are zinnias easy to grow?

Zinnias are one of the easiest flowers to grow. They can be sprinkled into wildflower gardens, and they will grow without any maintenance. Even though zinnias prefer rich, moist soil, they can tolerate poor soil and drought.

How tall do zinnias grow?

Zinnia plants can reach as high as 4 feet tall. They will spread out 1 to 2 feet wide. The Canary Bird Zinnia is one of the biggest plants, and its blooms are 4" wide.

Dwarf varieties grow only 6" to 12" tall.

How do you care for zinnias?

Zinnias don’t take any special care. They need warm temperatures and full sun. Zinnias will grow best in enriched soil that is moist but drains well. However, they can tolerate heat and dry conditions. Water weekly with a deep soaking for good growth and the best blooms. Avoid getting the leaves and flowers wet, which can lead to powdery mildew. Drip irrigation and soaker hoses work well (This is an excellent watering method for most flower gardens.)

When should I plant zinnia seeds?

The best time to plant zinnia seeds is when the soil and air temperature are 70º and above. Make sure that all danger of frost has passed.

Can I save zinnia seeds?

Zinnia seeds are easy to save and sow next year. At the end of the season, let the flowers continue growing until they go to seed. Once they are dry, they can be stored in envelopes to plant next season.

white zinnia flower

Tips for growing zinnias in a cut flower garden.

Zinnias are perfect flowers to grow in cutting gardens. They have big, colorful, long-lasting blooms that last 7 to 10 days in vases, which makes them easy to use in beautiful bouquets.

When growing zinnias in a cut flower garden, plants can be spaced 1 foot apart since you will be cutting the blooms often. Succession planting will also be vital so you can continuously supply fresh flowers.

When zinnia stems are stiff, not bendy, then they are ready to cut for flower arranging. You can learn more about cutting flowers in our blog.

We love growing zinnias in our flower garden. They are easy to grow from seed, and with so many blooms, they are fun to share in all kinds of bouquets. 

Take a look at the different varieties of zinnia seeds and try growing some in your garden. You might just discover having a green thumb is not so hard.

If you found this blog helpful, share it with your gardening friends!

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