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How Tall Do Zinnias Grow [Plant Size Guide]

Although most Zinnias look gorgeous in outdoor gardens due to their tall sizes, you can still grow some dwarf varieties inside your living space.  

Generally, the average Zinnia plant grows 1-3 feet high and 1-2 feet wide. However, there are also the tallest varieties, like Benery’s Gaint Series, reaching up to 4 feet tall, and the smallest ones, like Thumbelina, reaching only 6 inches.

Hundreds of Zinnia varieties come from three main Zinnia species: Zinnia elegansZinnia angustifolia, and Zinnia haageana.

So, this article will definitely help you to differentiate Zinnia varieties based on their height and pick the best of them based on your available space. 

Factors Affecting the Size of Zinnias

Zinnias are annual plants having a lifespan of only one year if you grow them indoors. However, they may live shorter due to the first frost outdoors.

You can also find some wild varieties of Zinnia that behave as perennial plants.

Zinnia seed takes nearly 10 days to sprout, and you will see it blooming in about 2 months in a perfect environment. 

When the flowers dry, they set seeds that develop into the new Zinnia plant after it comes in contact with the soil.

Zinnia can grow very tall
Tall Zinnia plants make your outdoor space incredible, whereas small ones are perfect for your indoor space.

You can harvest Zinnia seeds once the flower completely dries. If the seeds aren’t mature, they won’t germinate into a new plant.

Here are considerable factors that affect the height of the Zinnia.

  • Ideal Conditions: Zinnia needs 6-8 hours of direct sunlight and weekly watering for the best growth. Pests and diseases are also the factors affecting its size.
  • Fertilizer and Nutrients: Well-draining loamy soil and dilute balanced fertilizer once a month just before blooming will help it become taller with brighter blooms.
  • Spacing: Zinnia growing 2 feet tall will need about 18 inches of spacing for perfect growth. Crowded Zinnias may face stunt growth due to pests, diseases, and nutrient competition.
  • Pruning: Trimming the top of your Zinnia after they become 8-12 inches long with 2 sets of leaves will encourage the stem growth with lots of blooms.
  • Pests and Diseases: Pests like aphids and whiteflies spread different pathogens making your Zinnia weak with slow or stunted Growth. So Applying pesticides, fungicides, or neem oil once a week will prevent pests and pathogens.

How Tall Do Zinnias Grow?

Do you know Benery’s Gaint Series is the tallest Zinnia variety that can grow up to 4 feet tall and 2-3 feet wide?

Also, there are some dwarf varieties, like Thumbelina, that can only reach and spread up to 6 inches.

The average size of common Zinnias includes 1-3 feet in height and 1-2 feet in width. 

PlantHeight and Spread
Zinnia ‘Benary’s Giant Bright Pink’3-4 feet X 2-3 feet
Zinnia ‘Eldorado’2-3 feet X 1-2 feet
Zinnia ‘Enchantress’3-4 feet X 1-2 feet
Zinnia ‘Holi Pink’8-10 inches X 8-10inches
Zinnia ‘Inca’2-3 feet X 1-2 feet
Zinnia ‘Profusion Double Deep Salmon’2 feet 8 inches X 1-2 feet
Zinnia ‘Profusion Orange’1-2 feet X 1-2 feet
Zinnia ‘Purity’2-3 feet X 1-2 feet
Zinnia haageana ‘Old Mexico’1-2 feet X 1 foot 10 inches
Zinnia tenuifolia (Red Spider Zinnia)2-3 feet X 1-2 feet

From Editorial Team

Zinnia growth stages to consider!

The first growth stage of zinnia is germination which later develops into a complete plant. After about 2 months, the plant bears beautiful blossoms.

Usually, flowering occurs from mid-summer to early fall, and the plant pollinates itself during this duration.

Then, Zinnia bears seeds that fall on the ground after maturation and germinate in contact with soil.