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How to Grow Zinnias: Bold Blooms All Season

Colorful zinnia flowers field blooming in the garden on bokeh blurred background.
Photo Credit
mariokinhed/Shutterstock
Botanical Name
Zinnia elegans
Plant Type
Flowers
Sun Exposure
Full Sun
Soil pH
Neutral to Slightly Alkaline
Slightly Acidic to Neutral
Bloom Time
Summer
Fall
Flower Color
Multicolor
Orange
Pink
Purple
Red
White
Yellow
Special Features
Attracts Butterflies

Planting, Growing, and Caring for Zinnia Flowers

Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Looking to add a punch of color to your garden with zero fuss? Say hello to zinnias! These cheerful, daisy-like flowers are summer’s overachievers, blooming in bold colors from midseason to the first hard frost. Butterflies love them, gardeners adore them, and they make spectacular cut flowers. Even better? They’re practically foolproof to grow from seed! Let’s dig into everything you need to know about growing zinnias, your garden’s soon-to-be brightest stars.

About Zinnias - Are Zinnias Perennials?

Zinnias are annuals, so they’ll grow for one season to produce flowers and seeds, but the original plant will not come back in subsequent years. They have bright, solitary, daisy-like flower heads on a single, erect stem, which makes them great for use as a cutting flower or as food for butterflies.

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Types of Zinnias

The most popular zinnia species is Zinnia elegans, which has been bred to produce a great number of unique varieties.

Zinnia flowers come in three main kinds: single, double, or semi-double. The distinction between these forms comes from the number of rows of petals and whether or not the center of the flower is visible:

  • Single-flowered zinnias have a single row of petals and a visible center.
  • Double-flowered zinnias have numerous rows of petals, and their centers are not visible.
  • Semidouble-flowered zinnias are somewhere in-between, with numerous rows of petals but visible centers.

In addition to these forms, zinnia flowers come in a number of shapes, including beehive, button, and cactus. The plants also come in different heights: taller varieties are best for the background of a garden bed, while shorter varieties work well along a border. There’s a zinnia for every garden!

Plant zinnias in an annual or mixed border garden. Smaller zinnias are suitable for edging, windowboxes, or other containers.

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Planting

Where to Plant Zinnias

Choosing a location that gets full sun (6 to 8 hours of sunlight per day) is essential to getting plentiful blooms throughout the season. Additionally, a site that offers good air circulation will help to prevent foliar diseases such as powdery mildew later in the season.

Zinnias are able to adapt to most soil conditions, but the ideal soil will be rich in organic matter and well-draining. Soil pH should ideally be between 5.5 and 7.5. If soil is amended with compost (humus), the flowers will grow more quickly. Learn more about soil amendments and preparing soil for planting.

When to Plant Zinnias

  • It’s recommended that you grow zinnia from seed right in the garden bed, as they do not like to be transplanted. From seed, they will grow very quickly in the right conditions.
    • Note: Zinnias can be started from seed indoors if you prefer—just transplant them while they’re young and do so carefully.
  • Zinnias are sensitive to frost, so do not seed until the last frost has passed in your area. See your local frost dates.
  • Zinnias will grow in a minimum daytime temperature of about 60°F (16°C), though a range of 74°–84°F (23°–28°C) is preferred.
  • Sow a round of seeds every week or so for several weeks to extend the flowering period.

orange and red ZInnia with butterfly

How to Plant Zinnias

  • Space plants 4 to 24 inches apart, depending on variety. (Many common varieties are planted 6 inches apart within the row and 2 feet in between rows.) See the back of the seed packet for variety-specific advice.
  • Sow zinnia seeds only about 1/4 inch deep.
  • Most zinnia varieties grow tall and need staking to prevent their heavy stems from lying on the ground. A few weeks after planting, stake close to the plant stem. Take care not to injure roots.
  • Gardeners who grow many zinnias (especially for cutting) stretch pea netting over young plants between stakes and bamboo canes; the zinnia heads are then supported gently by the almost invisible netting. 

Growing

  • You’ll see zinnia seedlings in only 4 to 7 days for most varieties, though it will be anywhere from several weeks to a couple of months before blooms appear (depending on planting site and climate).
  • When seedlings reach 3 inches tall, thin them so that they’re 6 to 18 inches apart to maximize air circulation. This reduces the chance of powdery mildew developing.
  • Maintain moderate soil moisture and fertilize lightly to maximize growth and blooms.
  • After the zinnias flower, cut off the old flowers (a process called deadheading) to encourage more flowers to form.
  • Zinnias are annuals and will die with the first hard frost of fall. However, if you want them to reseed, let the last flowers of the season mature fully and scatter their seeds.

Types

  • Get a full-size flower on a compact plant with cultivars of the Dreamland Series. Dwarf and compact, these zinnias have fully double flower heads, up to 4 inches across in a wide color range; stems are 8–12 inches tall.
  • The Thumbelina Series cultivars are dwarf and spreading, with single or semidouble, weather-resistant flower heads in many colors. Their petals are 1-1/4 inch across and stems grow up to 6 inches long.
  • The State Fair Series are one of the biggest and tallest of them all, with large, double flower heads that are 3 inches across. Stems grow to 30 inches tall.

Harvesting

  • Zinnias generally take 60 to 70 days from seed to flower (though it depends on conditions and variety). They work great in a flower bouquet!

Saving Zinnia Seeds

To save zinnia seeds for replanting, simply collect a few blossoms that are at least halfway brown and let them dry in a paper bag until the seeds shatter. 

  • Find the dark, pointed seeds at the bases of outer petals, with more along the center of the flower.
  • Dry on a paper towel until hard and almost crisp.
  • Store in a paper bag in a dark, dry location until you plant again in the spring.

Zinnia bouquet on a kitchen table

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Pests/Diseases

  • Bacterial and fungal spots, powdery mildew, and bacterial wilt may affect zinnias. Minimize wetting of foliage and space plants properly to avoid disease.
  • Caterpillars, mealybugs, and spider mites also cause problems. Some leaf damage is not an issue, so avoid spraying unless there’s an actual infestation.
  • Luckily, zinnias are deer-resistant, so they might help keep nearby flowers from being eaten.

Wit and Wisdom

  • The small, narrow-leaf zinnias work well in hanging baskets and make for nice dried flowers, too.
  • It’s said that zinnias symbolize thoughts of absent friends. Learn about more flower meanings here.

Flowers
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

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Comments

<span>Anonymous</span> Mon, 07/23/2012 - 12:16
I have 2 orange & pink zinnias, which r fully bloomed. They r short plants 8inch in hight. Can I propogate them by seeds and how to collect those seeds.
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 07/23/2012 - 16:03
For a pure seed, you'd want to grow one zinnia variety at a time (or, they need to be 1/4 mile apart). Seeds are ready to harvest when the blooms begin to turn brown and dry. The seeds are contained in the very center. When the heads are completely dry, gently crush the heads between your hand and then carefully winnow away the chaff.
<span>Anonymous</span> Wed, 07/18/2012 - 18:27
i have red and white verigated zinnias in a pot. they r almost 4ft tall and have lots of blooms. tho some of the blooms resemble cone flowers and are kind of turning brown. why is that? also should i dead head my zinnias. if so, what is the best way to do so.
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 07/18/2012 - 20:36
Reseach shows that deadheading zinnias keeps them blooming. to deadhead, just pinch off the flower along with the seed receptacle beneath the flower's base (i.e., not just the petals). If the flowers are starting to turn brown, they are probably just old blooms. Be careful not to splash the leaves when you water and give your zinnias liquid fertilizer once a month to keep them blooming.
<span>Anonymous</span> Tue, 07/17/2012 - 22:51
I have a zinnia that has numerous buds on it but none of them have ever flowered. They turn brown and die. Now many of the leaves are brown. Any idea why this is happening and how to solve this problem?
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 07/18/2012 - 20:28
Do you have evidence of bugs? Look for tiny bugs or honeydew. If so, spray with insecticidal soap. That is a possibility though browning foliage is usually powdery mildew which can be treated with a fungicide spray. Also, ensure that zinnia get LOTS of sun for blooms and never get watered from overhead; wet leaves causes the mildew.
<span>Anonymous</span> Mon, 07/16/2012 - 22:35
My son attends daycare weekly and Friday he brought home a zinnia planted in a small foam cup it's about 6 or 7 inches tall with a few leaves no blooms should I transfer to a pot ? I really want to keep it alive sad to say but it's my first plant ever and I want him to be as proud of it as I am any tips would help thank you all !
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 07/18/2012 - 12:11
Zinnias are the perfect beginner flower! They do prefer to have their seeds sowed directly into the ground, but it's possible to transplant in the ground (or pot) if you don't disturb their roots. On a cloudy morning, gently remove the entire contents of the cup and place in the ground so it's level with the soil. It's best to put mix organic matter or a slow-release fertilizer in the hole first (ask your garden center). Water deeply, but don't let it get waterlogged. Then just water and weed! Water when the soil is dry to the first knuckle of your finger and then water deeply so it gets to the roots (5 inches down). Then wait between waterings until the soil dries out. It's best to water infrequently and deeply. They should get a total of 1 inch of rain/water per week. How to tell what 1 inch is? Put out an empty tin tuna can and measure the rain! It's fun for kids.
<span>Anonymous</span> Fri, 07/13/2012 - 17:36
My zinnia heads are tiny. Any idea why? Thank you.
<a title="View user profile." href="/author/editors">The Editors</a> Sat, 07/14/2012 - 20:32
Zinnas need LOTS of sun for full flower heads. They can also take a while to fully flower; some varieties are late summer bloomers.