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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> Sat, 07/14/2012 - 12:22
I have two different plants and one of them has small blooms and the other is massively big i have used the same amount of miracle grow on them and they are still the same size. The more sun they get the bigger they get too.
<span>Anonymous</span> Wed, 07/11/2012 - 21:57
I have never grown flower outdoors because where I use to live everything planted outside got eaten by deer and other critters. However since I have moved to a gated area my garden is going crazy. I have Zinnias with green bloomage are they just not old enough to turn color yet?? oh and can I put them in a pot with other flowers.
<span>Anonymous</span> Sun, 04/07/2013 - 02:51
There are varieties of zinnias that have green blooms. They are a unique variety and I am planting quite a few this summer.
<a title="View user profile." href="/author/editors">The Editors</a> Sat, 07/14/2012 - 20:28
Assuming they have lots of sun, some zinnia varieties are just late bloomers (August). They are fine in containers. Plant 6 inches apart. Zinnias are great companions for many annuals and also vegetables--from pole or bush beans to squash! They deter many insect pests and attract pollinators.
<span>Anonymous</span> Wed, 07/04/2012 - 20:03
I have just planted my adorable little lilliput zinnias in a small pot and plan to transplant it into another pot that is slightly larger. Are these plants alright if they stay potted? And if so, how many seeds should I put in the pot to prevent too many blooming flowers?
<a title="View user profile." href="/author/editors">The Editors</a> Sat, 07/07/2012 - 16:21
Yes, you can keep zinnias in containers. Just be sure to keep them well watered and moist since containers dry out more quickly. They'll still need lots of sunlight (6 hours a day). Feed the plants WEEKLY with a full strength, 5-10-5 fertilizer. (No timed-release fertilizer.) In terms of pot size, plant 1 zinnia per 6-inch pot, 3 zinnias per 10-inch pot, and 5 zinnias per 14-inch pot.
<span>Anonymous</span> Mon, 04/23/2012 - 12:26
I have newly baby zinnia and its about still in the 60's during day am I able to put the pot outside in the sun for little bits at a time as long as it doesn't get too cold so I'm guessing does anyone know what the temp gauge is on these zinnias?
<a title="View user profile." href="/author/editors">The Editors</a> Fri, 07/06/2012 - 21:41
Zinnias are ready for production in full sun with a minimum daytime temperature of 60°F.