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How to Grow Zinnias from Seed

Learn how to grow zinnias from seed with our step-by-step guide. Find tips on planting, care, and enjoying these vibrant flowers.

how to grow zinnias

Zinnias are known for their vibrant colors and easy-to-grow nature. These flowers can add a splash of cheer to any garden, coming in various shapes and sizes to suit your aesthetic.

Zinnias also make excellent cut flowers, with tall varieties that can grow up to 4 feet. Petal types include single, semi-double, and double petal arrangements, so you can mix and match varieties in a bouquet. 

In this article, I'll show you how to grow zinnias from seed, providing you with everything you need to nurture these beautiful blooms from the ground up.

Let's get growing!

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Zinnia overview

Botanical NameZinnia elegans, angustifolia or marylandica
Plant TypeAnnual flower
Plant Height8-48" (from dwarf to cut flower varieties)
Plant Spacing6-12" apart (depending on variety)
Sun RequirementsFull sun
Soil RequirementsFertile, well-draining soil with pH between 6 and 7
Water RequirementsWater deeply 2-3 times per week
Seed Depth¼"
When to SowDirect sow when soil temperature reaches 70°F
Start indoors 4 weeks before soil temperature reaches 70°F
Germination5-7 days
Days to Maturity75-90 days
Pinching & DeadheadingPinch when seedlings are 6-8" tall
Deadhead to encourage more blooms
Common IssuesPowdery mildew, blight, leaf spot, Japanese beetles

Zinnia varieties

There are two main species of zinnia with different growth habits. 

Zinnia violacea (also known as Z. elegans) grows upright and has broad leaves and large flowers. Z. angustifolia has a low-growing habit, narrow leaves, and white, yellow, or orange flowers. However, many hybrids of these two types exist called Zinnia marylandica.

zinnia elegans and zinnia marylandica seed packets

This year, I planted Senora, Queen Lime Blush, and Benary's Giant Coral in one of my raised garden beds. This mix of zinnias in complementary colors creates gorgeous bouquets that I can bring into the house!

zinnias growing in raised bed

What do zinnia seeds look like?

Zinnia seeds are flat, with one pointed end and one rounded end with a notch. They can be found in various shades of brown with a papery coating.

zinnia seeds on white background

When to plant zinnia seeds

Timing is everything when it comes to planting zinnias. These sun-loving flowers thrive in warm weather, so it's essential to wait until the danger of frost has passed before sowing the seeds directly into the garden soil.

For most regions, this means planting zinnia seeds in the late spring to early summer, once the soil has warmed up. If you're unsure about the right time for your area, a quick check with your local gardening center or cooperative extension office can provide valuable insights.

Where to plant zinnias

Picking the right location for your zinnias can make a world of difference in their growth and bloom. Here are some pointers to help you select the best spot in your garden:

Full Sun: Zinnias love the sun! They thrive best when they receive at least 6-8 hours of direct sunlight every day. The more sun they get, the more blooms they'll produce.

zinnias growing in raised bed in full sun

Good Air Circulation: Planting zinnias in an area with proper air flow can help prevent issues like powdery mildew. Space them appropriately, and avoid cramming them into overly tight spots.

Well-draining Soil: Zinnias aren't fans of wet feet. Plant them in areas where the soil drains well. Raised beds or slightly elevated patches can be ideal if you're dealing with dense or clay-heavy soil.

How to plant zinnia seeds indoors

Zinnias are among the easiest flowers to start from seeds at home, making them an excellent plant for beginning gardeners and kids. The large seeds sprout quickly and grow with minimal care.

Start seeds indoors in small pots or sterilized seed trays. Keep the pots in a sunny place at a temperature of 70 to 80°F with moist soil until germination in five to seven days.

zinnia seedlings in tray

When the plants have their true leaves, fertilize them once weekly with a dilute fertilizer solution. Pot up to larger containers if the seedlings get root-bound.

Harden off the plants for about one week before transplanting, and transplant during cloudy weather or evening to prevent transplant shock.

How to plant zinnia seeds outdoors

You can also plant zinnia seeds directly in the ground as spring weather warms up.

Sow seeds about ¼ inch deep and 8 to 24 inches apart, depending on the variety. Dwarf zinnias likes the ones shown below can be spaced about 6 inches apart. Larger ones may need 12 inches or more between plants.

Cherry Profusion Bicolor zinnias

Once you've chosen your spot and prepared the soil, make a small hole with your finger or a stick. Drop the seed in, and lightly cover. Gently press down on the soil to ensure good seed-to-soil contact, which will aid in germination.

After planting, give the seeds a good, gentle watering. You want to moisten the soil without causing erosion or washing the seeds away. Using a watering can with a fine rose or a soft spray setting on a hose works best.

zinnia seedlings growing outdoors

Until your seeds germinate, it's important to keep the soil consistently moist but not soggy. A light daily watering might be necessary, especially if you're in a particularly hot or windy location.

Zinnia seeds usually sprout pretty quickly, often within 5-7 days. Once you see those little green shoots popping up, you'll know your zinnias are off to a good start!

How to care for zinnias 

Once your zinnias have sprouted and are on their way to showcasing their vibrant blooms, it's essential to keep up with some basic care and maintenance routines. Here's how to ensure your zinnias flourish:


Zinnias prefer a somewhat consistent watering routine. Aim to water them deeply a few times a week rather than a little every day, which encourages deeper root growth. Water early in the day to reduce evaporation and to allow leaves to dry, minimizing potential disease issues.

queen lime zinnia

Allow the top inch of soil to dry out between watering once the plants are established. Avoid getting the leaves wet when you water because it can encourage fungal diseases.


While zinnias aren't super demanding, feeding them with a balanced, slow-release fertilizer at the time of planting can give them a good start. If you notice their growth slowing down or their color dulling during the season, a water-soluble fertilizer can give them a boost.

zinnia with flower bud on side shoot

Pinching and deadheading

Some gardeners swear by pinching back young zinnia plants when they're about 6 inches tall. Pinching out stems directly above leaves stimulates side branches and more blooms.

deadheading zinnia

Zinnias will also produce more blooms if you regularly remove spent flowers, a process known as deadheading. Not only does this encourage more flowering, but it also keeps the plant looking tidy.

Pests and diseases

While zinnias are relatively robust, they can sometimes attract pests like aphids or suffer from diseases like powdery mildew. Regularly inspecting plants and addressing any issues early on can keep your zinnias in top shape.

The biggest pest issue I encounter when growing zinnias is slug damage. They totally destroyed the leaves of these Candy Stripe zinnias and really impacted their blooms. I planted these seeds months ago and they're just now starting to flower!

slug damage on zinnia leaves

I deal with slugs eating my hostas as well, so I have a supply of Sluggo on hand all season. Just sprinkle it in the garden bed where you notice damage.

Now that you know how to grow zinnias from seed, you can enjoy their beautiful blooms every summer!