Article by Dean Ravenscroft, Ph.D. - Updated 15th Oct 2023
In this Gardener's HQ guide, we'll explore cultivating Zinnia plants in your garden, indoor spaces, and other settings.
At a Glance
- Plant Characteristics: Zinnias captivate with their vibrant colors and can vary in size from 8 to 36 inches (20 to 90 cm). With a blooming period stretching from summer until the first frost, they ensure gardens maintain a lively and colorful ambiance.
- Ideal Growing Conditions: Thriving in full sun with well-drained soil, Zinnias are suitable for zones 3 through 10, and are best sown after the last frost.
- General Care: To ensure prolonged blooming, engage in regular dead-heading and water well. Feeding in spring and pinching back encourages better growth.
Zinnia, Profusion flower: Cultivation & Garden Use
As Zinnia plants are not fully frost-hardy they are usually cultivated as half hardy annuals in the garden. They typically range from 8 to 36 inches (20 to 90 cm) in height, with both smaller and larger varieties available.
Zinnia by Photofarmer.
They can bloom from summer up to first frost. The Blooming season can be prolonged through regular dead-heading of spent flowers.
When in bloom, they may carry single or double blooms depending on the variety. The flowers are often vibrant shades of pink, purple, red, orange, or white.
They are able to grow in zones 3 through 10 (thriving best in warmer zones five and up), RHS Hardiness Rating H3, and can be sown out in the garden following the last frost.
Common species of Zinnia grown in gardens include Zinnia elegans which comes in a wide variety of vibrant colors, and has dwarf and tall varieties available. Zinnia angustifolia, better known as the Narrow-leaf zinnia, has a more compact growth and greater resistance to diseases. Zinnia grandiflora is a perennial species valued for its bright yellow blooms. Zinnia peruviana, has a lovely display of daisy-like flowers.
Beginner's Tips
- Easy Start: Zinnias are one of the easiest flowers to grow, making them perfect for newbie gardeners.
- Seeds or Seedlings: You can either sow seeds directly in your garden, or start with small seedlings from a nursery.
- Sunlight: They love the sun! Ensure they get at least six hours daily.
- Watering: Keep the soil moist but not soggy. Water at the base, not over the flowers, to prevent mold.
- Bloom Boost: For more flowers, regularly remove faded blooms.
How to Grow Zinnia
If growing Zinnia from seed, then sow outdoors following the last frost of spring. Lightly cover the seed once sown.
Plants should be spaced at 15 to 20 cm (6 to 8 inches; small), 25 to 30 cm (10 to 12 inches; medium), or 45 cm (18 inches; large species) apart.
Ideally grow Zinnia in a sunny area of the garden that receives afternoon shade. The plants are able to grow in most soils of pH 6 to 7. The soil should be enriched with manure for best results.
In cold areas, it may be a good idea to start off Zinnia seedlings indoors first. Do so about seven weeks in advance of transplanting.
It should take about one to three weeks to germinate seeds at a temperature of 20 to 27 degrees Celsius (68 to 80°F).
Transplant outdoors, after the last expected frost of spring.
Purple Zinnia by Dendroica Cerulea.
Zinnia Plant Care
It is easy to look after Zinnia plants. Keep them well watered, and feed them in the spring with a balanced liquid fertilizer (10-10-10 or 20-20-20). Be aware that over-fertilizing may lead to excessive vegetative growth at the expense of blooms, so follow manufacturer's instructions.
Pinch back Zinnia plants to encourage branching. Feed again once they start to flower. Remove decayed flowers.
Identifying Popular Zinnia Varieties: A Photo Guide
Zinnia elegans
Zinnia elegans, commonly known as the Common Zinnia, boasts vibrant, daisy-like flowers. It is a favorite choice among gardeners for its diverse range of colors and long-lasting blooms.
Full growing Guide available at How to grow Zinnia elegans.
Zinnia elegans (Elegant Zinnia / Common Zinnia / Youth-and-age), photograph by Forest and Kim Starr; CC.
Zinnia angustifolia
Zinnia angustifolia, also known as Narrowleaf Zinnia, has a compact growth habit and is a more hardy and disease-resistant option than other Zinnias.
Visit How to grow Zinnia angustifolia for an in-depth growing guide.
Zinnia angustifolia (Narrowleaf Zinnia), photograph by Eric Savage; CC.
Zinnia grandiflora
Zinnia grandiflora, the Rocky Mountains Zinnia, is cherished for its bright yellow blooms and can thrives in rocky environments.
Zinnia grandiflora (Rocky Mountains Zinnia / Plains Zinnia), photograph by Patrick Alexander; CC.
Zinnia acerosa
Zinnia acerosa, has numerous common names including Desert Zinnia, Wild Zinnia, and Spinyleaf Zinnia. It has spiny leaves and delicate daisy-like flowers. It is resilient, and thus well-suited for arid and desert landscapes.
Zinnia acerosa (Desert Zinnia / Wild Zinnia / Spinyleaf zinnia), photograph by Patrick Alexander; CC.
Zinnia haageana
Zinnia haageana, the Mexican Zinnia, is a great plant to grow if you wish to attract pollinators to your garden. It's vibrant, daisy-like flowers come in a stunning array of colors. Plant's have a bushy and compact growth making them ideal for borders, containers, or for use as a colorful ground-cover.
Zinnia haageana (Mexican Zinnia), picture by 阿橋 HQ; CC.
Commonly Grown Zinnia Hybrids
Zinnia Macarenia Bicolor
Zinnia Macarenia Bicolor, also knowna as Macarenia Zinnia carries striking long-lasting bicolor blooms. The vibrant petals are a combination of deep red and golden yellow.
Zinnia Bicolor Macarenia (Macarenia Zinnia), photograph by Swallowtail Garden Seeds; CC.
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Quick Zinnia Growing and Care Facts
Common Names: Zinnia: Rocky Mountain; Common; Purple; Plains; Desert; Wild; Spinyleaf; Narrowleaf; Bush; Mexican.
Scientific Names: Zinnia elegans (Common zinnia, Elegant Zinnia); Zinnia angustifolia (Narrow-leaf zinnia); Zinnia grandiflora (Rocky Mountain Zinnia, Prairie Zinnia.); Zinnia acerosa (Desert Zinnia); Zinnia peruviana (Peruvian Zinnia).
Life Cycle: Half hardy annual.
Height: 6 to 40 inches (15 to 100 cm).
Family: Asteraceae.
Native: Americas.
Growing Region: Zones 3 to 10.
Flowers: Summer until first frost.
Flower Details: White, yellow, yellow-green, cream, gold, burgundy, pink, red, purple, violet, orange. Multi, contrasting colors. Double ray florets; central disc. Dome. Papery.
Foliage: Green. Opposite. Linear through to Ovate.
Sow Outside: Cover seed. Following the last frost. Spacing 5 to 12 inches (12 to 30 cm).
Sow Inside: Germination time: one week to one month. Temperature 70 to 80°F (21 to 27°C). Seven or eight weeks in advance. Transplant outdoors following the last frost.
Care Requirements: Full sunlight or afternoon shade. Good drainage. Soil pH 6 to 7. Rich soil. Humus. Moist soil. Mix in manure. Regular watering to surrounding soil. Feed when transplanting. Feed at the start of flowering. Pinch tips.
Profusion flower (above) and Common Zinnia (below).
Common Questions
How many members does the Zinnia genus have?
The Zinnia genus includes about 20 species. They are well-loved for their vibrant, daisy-like flowers.
Are Zinnia species suitable for gardens, and which are most popular among gardeners?
Zinnias are popular in gardens due to their bright colors, easy care, and long blooming season. They add charm to borders and make delightful cut flowers. Specifically, Zinnia elegans (Common Zinnia) is a favorite among gardeners because of its diverse and vibrant flower colors.
Are members of the Zinnia plant genus fragrant?
No, they are not really known for having a strong fragrance.
What is the perfect location to grow Zinnia?
Zinnia plants thrive in a garden location that has full sun and a well-drained soil. As they are heat and drought tolerant they are ideal for sunny summer gardens.
Are Zinnias considered invasive in the USA?
No, they are not listed as being invasive in the USA.
How should I go about removing Zinnias from my garden?
Removing Zinnia is straightforward. Just pull out the entire plant, be sure to lift out the entire root system to prevent regrowth.
Summary
One of the reasons that I, and many other gardeners, love Zinnias so much is that they have vibrant daisy-like flowers, long-lasting blooms, and are incredibly easy to care for. Zinnia plants can include annual and perennial plants; these are native to the Americas. They are popular in gardens for their ability to bloom prolifically from late spring until the first frost.
Sow seeds directly into the ground in spring, once the threat of frost has passed. They prefer a sunny location and well-drained soil. Regular watering, deadheading, and feeding with a balanced fertilizer will keep them blooming throughout the season.
I hope that you enjoyed this guide on how to grow Zinnia plants. Learn how to grow Dahlia, Cyclamen, Chrysanthemum plant, and Helipterum plants in your garden.
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