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Zinnias: How to Plant, Grow, and Care for Zinnia Flowers | The Old Farmer's Almanac

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Zinnias

Colorful zinnia flowers field blooming in the garden on bokeh blurred background.
Photo Credit
mariokinhed/Shutterstock
Botanical Name
Zinnia elegans
Plant Type
Flower
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

How to Plant, Grow, and Care for Zinnia Flowers

Catherine Boeckmann
October 16, 2023
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Zinnias create a massive burst of color in your garden from summer through the first hard frost of fall. If you want these annuals to reseed, let the last flowers of the season mature fully. Learn more about growing and caring for zinnias.

About Zinnias

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 flowerheads on a single, erect stem, which makes them great for use as a cutting flower or as food for butterflies.

Types of Zinnias

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

There are three main kinds of zinnia flowers: single, semidouble, or 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.

Read Next

Planting

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 laying along the ground. A few weeks after planting, stake close to the plant stem. Take care not to injure roots. 
  • Gardeners who grow many zinnia (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 months before blooms appear (depending on planting site and climate).
  • When seedlings reach three 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.
Recommended Varieties
  • Get a full-size flower on a compact plant with cultivars of the Dreamland Series. Dwarf and compact, these zinnias have fully double flowerheads, 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 semi-double, weather-resistant flowerheads 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 flowerheads 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 your plant again in the spring.

Zinnia bouquet on a kitchen table

Gardening Products

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.
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.

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Comments

Hans (not verified)

4 months 3 weeks ago

My first crack at Zinnias. The first concrete pot planted a month ago
produced only six or seven plants, with one only two inches high. I did
place the seeds 3/4 of an inch into the new soil, which what I have red is
toooooo deep.

The second pot was all metal and it has excellent growth with most
of the seeds; all of which are about two inches high or more.

A week later I planted another ground based concrete planter with very
mix results. Many of the seeds never developed and the ones which did, are
only a little over one inch high.

I use David's Seeds out of Texas.
,
BTW, this piece was a very, fabulous read, indeed, especially for green horns
like meself.

It is too bad one can not download pictures.

Hi Hans, I'm not affiliated with this site, so I don't know if they have some kind of license for people to save the photos. I'm just researching zinnias, like you.

Right-click your mouse over a picture and there are several options (this is called a context menu), one being to "save as" and it will open your file manager and you can browse to where you want to save it.

cheers

J.B. Bulharowski (not verified)

4 months 4 weeks ago

My zinnia plant had quite a few flower buds (one had bloomed to a gorgeous pink hue) and today I found most of the buds neatly(?) pinched off underneath the plant. Wondered about animal, vegetable (joke) or human hands were responsible for the pruning. The rest of the plant is healthy and tall. Any ideas?

I have found that birds hack into the stem about 3inches below the bloom and suck out water. Anyone else see this happening?

Could it be a groundhog? They are known to like zinnias. Some chipmunks also like zinnias (especially seeds) and squirrels may occasionally nibble. Deer usually do not like zinnias but may eat them in certain cases. Some rabbits will nip zinnias, with clean cuts, while others avoid these flowers. Birds will go after the seeds and pull petals off. Some of these animals will eat during the night. 

Lora L Soderholm (not verified)

5 months 2 weeks ago

I planted my Zinneas in flower boxes and they now have buds, however, the leaf edges are turning kind of yellow and crunchy? What's up?

Kathy (not verified)

6 months 2 weeks ago

If zinnias get too tall can you cut them back so they get bushier?

Hi, Kathy. For bushier zinnias, you need to cut back stems while the plant is young. If your zinnias get too tall, you can do a hard pruning by cutting back the plant by about two-thirds.

Thank you so much from a gardeners experience. I realize zinnias are pretty simple to grow, but I’m still kinda concerned about WHERE to plant them.
Will them keep reseeding? I’ve read yes, I’ve heard no.
I’ve got an 8 hr eastern sun exposure.
Does this work?