How Far Apart Should You Space Zinnias When Planting Them?

If you are planting zinnias in your garden, you may be wondering how far you need to space them from one another, and how far the rows should be apart. In this article, gardening and flower expert Taylor Sievers walks through exactly how much distance these flowers need between each other, and between rows.

Colorful Zinnias Growing in Garden

If there’s one flower staple in the home garden I had to choose, then the zinnia would have to be it! These heat-loving Mexican natives are easy to start from seed, and are low maintenance. They also produce a jazzy pop of color all throughout the summer.

Zinnias can have versatile applications in landscaping and home gardens as long as you have a warm, sunny spot on your property. Plant a low-growing Zinnia angustifolia along a landscape border, a unique two-toned Zinnia haageana variety in a patio container, or a giant-flowered Zinnia elegans variety as a companion plant in your vegetable garden! None of these species will disappoint when it comes to cheeriness.

Okay–so now you’ve decided to add zinnias to your must-grow list. But zinnias don’t just come in one species or one height! And now you may be wondering, how far apart should I be planting my zinnias? Read on to learn more about zinnias and plant spacing specifics!

How far apart should I space zinnias when planting?

Spacing depends on what variety you are planting and what your purpose is for your zinnias. Smaller zinnia varieties used as a border plant or in pots could be planted as close as 6 inches apart, while larger giant-flowered varieties may need up to 18 inches of space between each plant. If you live in a hot, humid climate, you may consider spacing your zinnias further apart to increase air circulation through the plants, and this will reduce disease incidence as well.

About Zinnias

Purple Zinnias
This beautiful flower can be grown in nearly any color.

Plants of the Zinnia genus are considered herbaceous annuals. This means they produce non-woody growth (for the most part). They will flower and set seed within one year or season of growth. They prefer full sun (6 to 8+ hours of direct sunlight per day) and well-draining soil.

Zinnias produce bright, cheerful blooms in almost every color but blue. Flowers can be as small as an inch in diameter to 5 inches, depending on the variety. Some zinnia varieties are single-petaled (meaning they have one row of petals) and others will be double or multi-petaled.

Because they are members of the Asteraceae family, their flower is actually a composite flower. This means that what you see as the flower head is actually multiple small flowers. The “petals” are called ray flowers and the center portion of the flower is filled with disk flowers.

Zinnias can be prone to diseases like leaf spot diseases or powdery mildew. It’s important to make sure that any dew or moisture on the leaf surface can dry quickly. Spacing your zinnias further apart will help promote natural air circulation through the flower patch. You’ll notice dying zinnias usually turn brown before they are completely dead.

Watering at the base of the plant rather than overhead will help reduce moisture on the foliage. Planting in full sun will also help the foliage dry off faster in the morning from the dew that will collect on the leaves at night.

Zinnia Planting Tips

Colorful Zinnias Growing in Garden
Different varieties of this swoon-worthy flower will require different spacing in your garden.

Zinnias should be planted after your last expected frost as they do not tolerate cold temperatures. Usually it is best to wait until the soil has reached at least 55⁰F before planting zinnias outside. They can be started indoors about 4 to 6 weeks before your last estimated frost date if you’d like to get a jumpstart.

Plant zinnias anywhere from 6 inches apart to 18 inches apart. Small bedding varieties that only reach about 8 inches in height can be planted between 6 to 10 inches apart. Larger varieties that reach up to 4 feet tall should be planted between 12 to 18 inches apart.

In my cut flower garden, I plant my large ‘Benary’s Giant’ zinnias in a grid that is 9 inches by 9 inches apart. This promotes longer, straighter stems, which is what I’m looking for as a cut flower grower. However, in the landscape I would normally plant these at least 12 inches apart, for reference. Zinnias can be planted indoors or outdoors. Outdoor planting can be beneficial, especially if you’ve saved a bunch of zinnia seeds from a prior harvest.

Direct Sowing Outdoors

Hand Planting Flowers in Garden
Direct sowing of seeds is one of the more popular planting methods for these flowers.

If you are direct sowing seeds outside, make sure to plant the seeds at least ¼ inch deep. You can plant them in a furrow and thin the seedlings to your desired spacing after they germinate. You may broadcast seeds, but you will need to rake them into the soil to promote seed to soil contact. Be aware that you may have reduced germination. You will likely need to thin out your seedlings if you are broadcasting seeds. Obviously, if you let your zinnia reseed itself, you’ll have a bit less control.

Thinning is the practice of uprooting and removing seedlings that have emerged. This ensures that your entire planting has correct spacing between plants. Gardeners will overseed sometimes when they are direct sowing into the garden.

This is because they know it’s likely some seedlings will not germinate for various reasons. Then they can thin out seedlings later that are not needed. It can be painful to thin your plants. But, if you leave your plants too close then you’ll have less vigorous plants that are competing for sunlight and moisture.

Seed Starting Indoors

If you are starting seeds indoors, make sure to plant the seed at least ¼ inch deep in your cell tray or small pots. I like to poke holes in the cells using a pencil and drop the seeds in before covering and dusting the surface with vermiculite. Heat mats will definitely give you a jumpstart on germination.

Close up of Pink Flower
This gorgeous ‘Uproar Rose’ variety is just one of many possible additions to your garden.

Here are a few popular varieties along with recommended spacing for these varieties:

  • ‘Benary’s Giant’ series zinnias will grow 3 to 4 feet tall with 4 to 5 inch blooms in 13 different colors. Plant this variety between 12 and 18 inches apart.
  • ‘Uproar Rose’ is a stunning, large, rose-colored zinnia that is well-branching. Plant this variety between 12 and 18 inches apart.
  • ‘Queen’ series zinnias have blooms in antique shades of rose, orange, and blush that fade into lime. These zinnias should be spaced between 10 and 12 inches apart.
  • ‘Oklahoma’ series zinnias come in a range of colors, but the blooms are much smaller at about 2 inches in diameter. Space these plants between 10 to 12 inches apart.
  • ‘Crystal’ series zinnias top out around 10 inches tall and is a single-petaled variety in colors of orange, white, and yellow. This zinnia could be planted between 6 to 10 inches apart.
  • ‘Aztec Sunset’ zinnias can grow up to 2 feet tall with smaller 1 to 2 inch flowers in red, yellow, orange, and bicolor orange and maroon. Space this variety 10 to 12 inches apart.
  • ‘Soleado’ has bright, cheerful blooms in orange or yellow with a mahogany ring around the center. Space this variety between 10 and 12 inches apart.

Frequently Asked Questions

How far apart should I space zinnias in pots?

Shorter varieties of zinnias are excellent candidates for patio pots. Remember to think about the spread of the variety you are planting. Spread means how wide the plant will get at maturity. For the most part, the smaller varieties or dwarf varieties of zinnias will need to be planted at least 6 inches apart from a neighboring plant. If you’re planting in a very small pot (6 to 10 inches wide) you may consider only planting one zinnia plant per pot.

Why plant zinnias?

Zinnias are versatile plants in the garden or landscape. They can be planted in the vegetable garden, cut flower garden, landscape, or in a pot. They attract beneficial insects, especially pollinator insects that are important for certain fruit and vegetable plant pollination and fruit set.

Also, zinnia flowers come in very bright and attractive colors, providing a cheerful pop of color to a flower arrangement or in the landscape. The more you cut these flowers, the more they will bloom. Zinnias love full sun and well-drained soil, and they’ll thrive in the mid to late Summer heat.

Where do zinnias grow best?

Zinnias grow best in full sun (at least 6 to 8+ hours of direct sunlight per day). They prefer well-draining soils, but it’s not hard to grow them in other soils, like clay. The diseases that may plague zinnias, like powdery mildew and leaf spots, will have less of a chance of infection if the site where you’ve planted your zinnias has excellent air flow.

Excellent air circulation will reduce the amount of time that dew or rainwater rests on the plant leaves, which in turn will reduce the incidence of disease prevalence. Spacing zinnias adequately will help promote air circulation as well!

Final Thoughts

Zinnias are a wonderful plant to include on your garden list every season! There are many varieties and colors to choose from. So, there’s likely a zinnia for almost every spot in your garden or landscape (except full shade, remember?).

Spacing zinnias correctly is important for disease concerns and decreased competition between neighboring plants. It will also help make your garden aesthetically-pleasing. It’s important on know what variety you’re planting and where it’s going to be planted. After you have those basics, sit back and enjoy the beauty of zinnia blooms all Summer long!

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