How To Grow Zinnias From Seeds Indoors: 5 Easy Steps

Last Updated on December 19, 2022 by Cristina

Zinnias are one of the prettiest flowers that you can grow. Learning how to grow zinnias from seeds indoors is a beneficial thing for any gardener to know. It is relatively easy to do and is something that gardeners of any experience level can achieve.

The beautiful, colorful blossoms of zinnia flowers will stand out in your garden. These attractive flowers are one of the most popular additions to gardens. They are a particularly great choice to grow if you are looking to attract butterflies to your yard.

All About Zinnias

Zinnias are a type of annual that is a member of the Asteraceae family. There are different species with Zinnia Elegans being the most popular.

Zinnias can be single, semidouble, or double. The distinction between these flowers comes from the number of rows of petals and whether or not you can see the center of the flower.

Zinnias can come in many different colors including orange, multicolor, red, pink, purple, white, and yellow. They can be grown outdoors in USDA zones 3-10. They are relatively easy to care for and can make a beautiful addition to bouquets.

How To Grow Zinnias From Seeds Indoors

Zinnia seeds can be sown directly into the soil outside. However, you can also get a head start and begin growing your seeds indoors. This is a great option if it is still cold out where you live at the beginning of spring.

When planting zinnia seeds indoors they should sprout within weeks. Once established, you can transplant the healthy seedlings outdoors. They can grow in a garden bed or a container, depending on the space you have where you live.

It is important to know when to start zinnia seeds indoors. You should start them inside five to seven weeks before when you plan to plant them outside in spring. You only want to plant them outside when the last freeze has passed otherwise your plants may not survive.

Prepare The Soil And Containers

To start, prepare the soil and the containers you are going to plant your zinnia seeds. You can use a seed tray or peat pots to plant your zinnia seeds.

You should use a starter potting mix that is well-draining for your zinnias. After adding your soil to your peat pots or seed trays, moisten it in order to prepare it for your seeds.

Plant The Seeds – How To Grow Zinnias From Seeds Indoors

After preparing your peat pots or seed trays with a starter potting mix that is well-draining, add your seeds. Knowing how deep to plant zinnia seeds is important for your seeds successfully sprouting.

Place your seeds 1/4 inch to 1/2 inch down and cover them with soil and then moisten the soil. Place two to three zinnia seeds per compartment.

Keep The Soil Moist And Provide A Sunny Location

Continue to keep the soil moist and keep your container on a sunny windowsill to ensure your seeds get enough sunlight. If you don’t have a sunny windowsill for your zinnias to grow, you can use fluorescent plant lights.

Keep the lights on for 16 hours a day and place them three to four inches above your containers. Move the lights up as the plants grow for optimal growth.

Keep your containers in an area where the temperature is between 70 to 75 degrees Farenheit. If your house is chillier than that you can use a heating mat for your containers to encourage germination.

Move To A Sheltered Place Outside

Once the seedlings begin to grow, thin to one seedling per cell once they have two sets of leaves. Around three to four weeks you can add a starter solution fertilizer at half strength according to the manufacturer’s instructions.

After your seedlings are established, move them to a sheltered place outside to harden. Be sure to protect them from wind and harsh sun and also bring them inside if the temperatures get too cold at night. The hardening-off process toughens the cell structure of the plant while also reducing shock and scalding when transplanting.

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Transplant The Seedlings – How To Grow Zinnias From Seeds Indoors

Once the soil is warmed up outside to about 70 degrees Farenheit and the last frost is over, you can transplant your seedlings to your garden.

Carefully dig holes in your garden that are at least 12 inches apart. Carefully transplant your zinnias to the garden, covering them with soil and then watering them. If you planted your seeds in peat pots you can plant them directly into the soil.

Caring For Zinnia Plants

Zinnia plants are relatively easy plants to care for and make great flowers to grow in your garden. With the right steps, you can successfully grow bright, colorful zinnia plants.


Zinnias are drought-tolerant flowers. When grown outside they typically don’t need supplemental water as long as you get regular rain.


Zinnias can adapt to most soil conditions, but the soil should be well-draining. Ideally, the soil for zinnias should be rich in organic matter.

Sunlight – How To Grow Zinnias From Seeds Indoors

Zinnia light requirements are often easy to meet. They do best when you grow them in an area with full sun.

Temperature And Humidity

Zinnias can continue to grow in hot summer temperatures. They don’t have specific humidity requirements, so you don’t have to worry about that when planting your zinnias.


Zinnias can benefit from occasional feedings of a well-balanced fertilizer, however, it is not necessary. Be sure to read the instructions before fertilizing your zinnias.

Caring For Zinnia Plants

Containers Or Garden Bed 

While most people grow zinnias in gardens, you can also grow zinnia in pots, though they do best in gardens. Your pot needs to be at least 12 inches wide and 12 inches deep.

How To Grow Zinnias From Seeds Indoors: What To Know

Growing zinnia flowers from seeds indoors is simple as long as you follow the steps above. Their bright, beautiful colors will stand out in your garden and they are simple flowers to care for, making them great for all levels of gardeners.

Do you have any questions regarding how to grow zinnias from seeds indoors? If so, please ask your zinnia growing questions in the comments.

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