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Zinnias: Planting, Growing and Caring 101

What are Zinnias

Zinnias are everyone’s favorite summer flower. They’re easy to grow, come in various colors and attract beautiful butterflies in your garden. 

It’s no wonder why newbie or seasoned gardeners want to add them in their yard. Lucky for you, you’re on the right page, as we’re here to walk you through everything you need to know about planting, growing and caring for zinnias. 

So, keep reading to learn how to start growing zinnias today!

What are zinnias?

What are zinnias
Image: Martha Stewart

Zinnias are annual flowering plants indigenous to Mexico. They are known for their bright colored flowers and easy care nature, making them a favorite ornamental plant in most gardens.

Zinnias come in different shapes, such as single, semi-double or fully-double flowers. They also come in globe, dahlia or even cactus flower forms.

They’re easy to plant and care for, requiring only full sun and well-drained soil, and they will bloom beautiful pink, purple, yellow, orange, white, red, or green flowers all summer. 

Zinnias are a popular choice for ornamental plants or flower arrangements and wreaths. They’re also used to make dyes or potpourirs.

At a glance, here’s an overview of the physical characteristics and planting conditions for zinnias. 

Scientific NameZinnia elegans
Common NameZinnia
Plant TypeAnnual
Country or Region of OriginMexico
South America
North America
Size6 inches to 3 feet tall8 inches to 1 foot wide
LightFull Sun
SoilHigh Organic Matter
Bloom TimeSpringSummerFall
Flower ColorsPink
USDA Plant Hardiness Zone2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b, 11a, 11b
Growth RateRapid
Container plant
Border plant

What are the types of zinnias?

What are the types of zinnias
Image: Gardener’s Path

The three main kinds of zinnias are single, semi-double and double flowers. They vary in the number of rows of petals and the visibility of the center of the flower.

Here’s a summary of the key features of each kind of zinnia. 

TypeNumber of Petal RowsVisibility of Center of FlowerExample Species
Single OneVisible Zinnia elegans Zinnia angustifolia
Semi-doubleTwo to threePartially visibleZinnia marylandica, Zinnia tenuifolia
DoubleFour and aboveNot visibleZinnia haageana

We’ve also listed down the best zinnia varieties in the table below. Check out each type of zinnia flower and choose according to your needs. 

Common NameScientific NameHeightNumber of Petal Rows Flower ColorsKey Features
ThumbelinaZinnia elegans Thumbelina6 to 12 inchesSingleRed
Dwarf size
Container plant
State FairZinnia elegans State Fair24 to 36 inchesDoubleRed
Large flowers
ZaharaZinnia elegans Zahara18 to 24 inchesDoubleRed
Resistant to powdery mildew and leaf spot
DreamlandZinnia elegans Dreamland18 to 24 inchesSemi-doubleRed
Flowers in shades of pink and red
EnvyZinnia elegans Envy24 to 36 inchesDoubleRed
Resistant to powdery mildew and deer
Orange starZinnia elegans Orange Star18 to 24 inchesSingleOrangeBright orange flowers
Creeping Zinnia Zinnia angustifolia6 to 12 inchesSingleRed
Low-growing Groundcover
MagellanZinnia haageana Magellan12 to 18 inchesDoubleRed
Compact Border plant
CrystalZinnia marylandica Crystal24 to 36 inchesSingleWhiteLarge, white flowers

How to Grow Zinnia

After choosing a zinnia variety for your garden, it’s time to learn how to grow them. Zinnias are relatively easy-to-grow flowers that even newbie gardeners can do it.

Read on to learn the basic steps in growing zinnias. 

1. Choose the right location.

Choose the right location
Image: Gardens Illustrated

Zinnias grow best when they get full sun, ranging from 6 to 8 hours per day, and well-drained soil. 

Growing them in a sunny location is crucial, so you’ll get plenty of blooms throughout the season. Another benefit is that it will provide good air circulation around the plant, preventing pests and diseases like powdery mildew. 

Zinnias love moist, well-drained soil rich in organic matter and with a soil pH between 5.5 and 7.5. You can also amend the soil with humus or compost so they can grow flowers more quickly. 

2. Prepare the seeds. 

Prepare the seeds
Image: Minneton Orchards

Zinnias can easily be propagated using their seeds. Simply let the flowers dry out entirely on the stem and harvest the seeds by crushing the seed head. 

You can store the seeds in a cool, dry place as you wait to plant them in the upcoming spring season. The good news is these seeds will last forever.

3. Sow the seeds indoors.

Sow the seeds indoors
Image: Celtic Roots Farm
DifficultyAverage ●●●○○
Duration6 to 8 weeks
Things You NeedZinnia seeds
Potting mix
Seedling tray
Watering can
Balanced fertilizer

Zinnias grow best when they’re sown indoors if you want them to bloom earlier. We recommend starting them indoors about six weeks before the last frost date so they’ll have a head start in growing and producing flowers. 

Zinnia seeds will germinate within 3 to 5 days from planting as long as the ideal temperature of 80 to 85°F (27 to 29°C) during the day and 60 to 65°F (16 to 18°C) at night are maintained. 

If you want a continuous supply of zinnia flowers, you can sow a round of seeds every week to extend their flowering period. Check out the easy steps below on how to sow zinnia seeds indoors. 

How To Do
1. Fill the seedling tray with the potting mix. 
2. Sow the zinnia seeds about ¼ inch deep into the soil. 
3. Water the seedling tray lightly. 
4. Place the seedling tray in a sunny location.
5. Keep the soil moist. 
6. Wait for the seeds to germinate within 3 to 5 days. 
7. Thin the seedlings to 2 to 3 inches apart.
8. Move the seedlings to an area with 6 to 8 hours of sunlight. 
9. Fertilize the seedlings using a balanced fertilizer every two weeks. 
10. Harden off the seedlings before transplanting them to a pot or garden bed.

4. Harden off and transplant the seeds outdoors.

Harden off and transplant the seeds outdoors
Image: Garden Gate Magazine
DifficultyAverage ●●●○○
DurationTwo weeks
Things You NeedZinnia seedlings
Watering can

After germinating zinnia seeds indoors, hardening them off before transplanting them outdoors is important. 

Hardening off is a gardening technique of gradually exposing the seedlings to outside weather conditions. This will prevent transplant shock, which can weaken and disrupt their growth and flowering processes. 

We recommend that you start hardening off the zinnia seedlings two weeks before moving them outdoors. Once they’re used to the outside growing conditions, carefully transplant the zinnia seedlings to your chosen location. 

Below are steps on how to harden off and transplant your zinnia seedlings. 

How To Do
Hardening Off
Begin by placing the zinnia seedlings in a shady location for 2 to 3 hours. Place the seedlings in the exact shady location for 4 to 5 hours the next day. Increase the number of hours the seedlings will spend under the location until they can tolerate full sun for 6 to 8 hours daily. Water the seedlings regularly. 
Till the soil and add compost. Then, water the soil. Dig a hole for each seedling twice as wide and deep as its root ball. Gently remove the seedling from the tray and transfer it to the hole. Fill the hole with soil and even it out gently. Water the seedling. Apply mulch around the seedling to retain moisture and suppress weed growth.

5. Enjoy and harvest zinnia flowers.

Enjoy and harvest zinnia flowers
Image: HGTV

After successful transplanting, all you have to do is water the zinnia plants once every two to three days and fertilize them every two weeks. 

Gardeners usually deadhead the plant or remove spent blooms to encourage the zinnia plant to produce more flowers. Within 60 to 70 days from planting, you’ll now enjoy the sight of those colorful zinnia flowers.

What diseases do zinnias get?

The most common diseases that zinnia plants get are powdery mildew and zinnia blight.

Keep reading to know how they affect zinnias and how to treat them.

1. Powdery Mildew

Powdery Mildew
Image: PNW Handbooks

How To Fix: Spray the plant with baking soda solution.

Powdery mildew is a fungal disease that leaves a graying white coating on the plant’s leaves, stems and flowers. It causes the yellowing of leaves until they fall off and kill the entire plant. 

Solution: Spray the plant with baking soda solution.

DifficultyEasy ●●○○○
Things You NeedOne tablespoon of baking soda
1 gallon of water
Spray bottle

How To Do 
1. Thoroughly mix one tablespoon of baking soda and one gallon of water.
2. Pour the solution into the spray bottle. 
3. Spray the plant with the baking soda solution, especially the underside of the leaves.
4. Repeat application every 7 to 10 days or until the powdery mildew is gone. 

2. Zinnia Blight

Zinnia Blight
Image: PNW Handbooks

How To Fix: Apply fungicide.

Zinnia blight is another fungal disease where brown, water-soaked spots develop on the zinnia plant’s leaves, stems and flowers. These spots grow large and merge, causing the leaves, stems and flowers to wilt and the plant to die.

Solution: Apply fungicide.

DifficultyEasy ●●○○○
Things You NeedFungicide
Watering can
Spray bottle

How To Do
1. Mix the fungicide with water based on the product label. 
2. Wear gloves for protection. 
3. Pour the fungicide mixture into the spray bottle.
4. Spray the fungicide on the plant, even the underside of the leaves. 
5. Repeat application every 7 to 10 days until zinnia blight is gone.

Zinnia Companion Plants

Zinnia Companion Plants
Image: Garden Gate Magazine

Companion planting with zinnia plants is a great way to fill your garden with pollinators and keep the pests away. As long as these companion plants have similar growing conditions with zinnia, they can grow together in your garden. 

Here’s a table of the best companion plants for zinnias and their benefits. 

Common NameScientific NameBenefits
MarigoldTagetes erectaRepels pests like aphids and whiteflies
Attracts pollinators like bees and butterflies
CosmosCosmos bipinnatusProvides shade for zinnias
Attracts pollinators
NasturtiumsTropaeolum majusDeters pests like aphids and slugs 
Attract pollinators
SunflowersHelianthus annuusProvides shade for zinnias
Attracts pollinators
StrawflowerHelichrysum bracteatumAttracts pollinators 
Deters pests
CleomeCleome hasslerianaProvides shade for zinnias
Attracts pollinators
LarkspurDelphinium consolidaAttract pollinators
YarrowAchillea millefoliumDeters pests like deer and rabbits 
Attracts pollinators

FAQs on Zinnias

Are zinnias annual or perennial?

Zinnias are annual plants that die every season and only return if you plant their seeds again. 

Do zinnias attract bees?

Zinnias attract bees because of their colorful flower heads, which produce a lot of nectar and pollen they feed on.

Do zinnias spread?

Zinnias spread through their seeds. When their seeds fall to the ground, they can germinate during the following spring and produce new zinnia plants. 

Will zinnias rebloom after cutting?

Zinnias will rebloom after cutting them, earning them the nickname “cut-and-come-again” flower. They will continue to produce flowers even after you deadhead them or cut off the spent flowers.

Do zinnias need deadheading?

Zinnias need deading so they can produce more flowers for an extended period. When you remove the spent flowers, the plant is prevented from setting seed, which encourages it to produce more blooms.

Do zinnias need pruning?

Zinnias need pruning to encourage vigorous growth and production of more flowers. Removing excess stems will help provide better air circulation and prevent pest infestation, while removing spent blooms will encourage it to produce more flowers.

Do zinnias need fertilizer?

Zinnias need fertilizer as they are heavy feeders. They need balanced fertilizers every two weeks to grow stronger leaves and stems and produce more colorful flowers. 

Can zinnias grow in pots?

Zinnias grow well in pots if the soil is well-drained and the pot contains drainage holes to allow excess water to leak out and prevent root rot. 

What time of day is the best for cutting zinnias?

The best time of the day to cut zinnias is in the morning after they are fully open. This preserves the freshness of the flowers and prevents them from wilting. 

How long do zinnias bloom in the garden?

Zinnias bloom from early summer until the first frost. You can enjoy their colorful flowers for up to six months a year with proper care.

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