Quick Guide to Growing Zinnias

Warm Season Annual
Best Soil: Well-drained, rich in organic matter
Sunlight: Full sun (6+ hours)
Watering: Water at the base, 1” per week
Care Tips: Deadhead spent blooms, space properly for airflow

Zinnias (Zinnia elegans) are one of the most popular and well-known summer annuals in the United States. The unremarkable ancestors of modern-day zinnias are native to the Southwestern United States, Mexico, and Central America. These small, weedy parent plants have insignificant, daisy-like, purplish-red flowers. In Spanish, they are called mal de ojos, meaning “evil eyes” in English.

Zinnias (Zinnia elegans) are one of the most popular and well-known summer annuals in the United States.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

Modern-day zinnia flowers have many colors, including red, pink, purple, yellow, orange, white, green, and multi-colored hues.
Barbara H. Smith, ©2019 HGIC, Clemson Extension

Zinnias were named in honor of Dr. Johann Gottfried Zinn, a German botanist who first wrote about them in the 1700s. It was 100 years later before zinnias were selectively bred. Zinnias gained popularity in the 1920s when the Bodger Seed Ltd. company in California first introduced the well-known cultivars ‘Giant Dahlia’ and ‘California Giant.’ England’s Royal Horticultural Society awarded a gold medal to ‘California Giant’ zinnias. Today over a hundred Zinnia elegans cultivars are available on the market.

Modern-day zinnia flowers are available in various colors, including red, pink, purple, yellow, orange, white, green, and multicolored mixes. The flower sizes range from small 1-inch blooms to 7 to 8 inches across on larger cultivars. They come in a variety of shapes, including singles, semi-doubles, and doubles and range in height from 6 inches to 4 feet tall. Each year, new Zinnia elegans cultivars are being developed by plant breeders and are available as seeds and transplants in the retail market.

How to Grow

From Seed: Seeds may be directly sown in the garden when the chance of the last frost has passed in the spring. The ideal soil and air temperature should be around 70 °F. When sowing seeds, plant them ¼ inch deep. When the seedlings are 3 inches tall and, depending on the cultivar, thin them 8 to 24 inches apart to allow for better air circulation. After direct sowing seeds, zinnias will mature and bloom 8 to 12 weeks after planting.

From Transplants: Transplants are also available on the market. Space the plants according to the label directions, as overcrowding leads to an increased incidence of disease. Transplants should not be planted any deeper than the top of the root ball.

It is essential to properly space zinnias, whether growing from seed or transplants, as overcrowding increases disease incidence. Dwarf cultivars should be planted or thinned 8 to 9 inches apart, whereas taller 2- to 3-foot zinnia cultivars should be spaced a foot apart. They prefer being planted in fertile, organically rich, well-drained soil with at least 6 hours of full sun. When planting multiple rows of zinnias, space the rows a foot apart. Proper air circulation will help to dry the leaves and prevent powdery mildew.

Zinnias need to be watered regularly, but water at the base of the plants, as getting the foliage wet will encourage leaf spot diseases. A soil test is recommended before fertilizing. For more information on soil testing, see HGIC 1652, Soil Testing.

Landscape Use

Depending on the mature size of different cultivars, zinnias can be used in containers, borders, or mass plantings. They are an excellent choice for a cutting garden as zinnias have a long vase life of a week or more.

Zinnias are also an excellent addition to a pollinator garden. They will attract a wide variety of hummingbirds, butterflies, bees, insects, and other pollinating insects. For more information on pollinator gardens, see HGIC 1727, Pollinator Gardening.

A wide variety of butterflies visit zinnia flowers. The Eastern swallowtail butterfly (Papilio glaucus) is a frequent visitor.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

A bumble bee (Bombus sp.) and snowberry clearwing moth (Hemaris diffinis) gather pollen and nectar from a California Giant zinnia flower.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

Red, orange, and pink zinnia flowers provide a rich nectar source for a female ruby-throated hummingbird (Archilochus colubris).
Barbara H. Smith, ©2024 HGIC, Clemson Extension

A zinnia mix is an excellent choice to plant for a cutting garden.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

Best Practices for Cutting & Arranging Zinnias: The best time to cut zinnias for an arrangement is in the morning when the temperatures are cooler, and the flowers are well-hydrated. When cutting flowers for a bouquet, cut to just above a leaf node (where two leaves grow opposite each other) with a sharp pair of clean scissors or pruners. Cutting above the leaf node will encourage new flower buds and leaves to form at the leaf node and prevent brown stubs on the stem. Choose flowers whose centers are just beginning to open fully to prolong the life of the cut flowers. Always remove the lower leaves before placing the flowers in a vase filled with room-temperature water. Removing the leaves and changing the water every 2 to 3 days will prevent bacterial growth and prolong the arrangement’s life.

Care

Watering Tips for Healthy Zinnias: It is important to avoid overhead watering, as this may lead to fungal and bacterial disease problems. Use a soaker hose or drip irrigation to water at the base of the plants. Water zinnias when the top 1 to 2 inches of soil feels dry and apply 1 inch of water per week. Avoid overwatering as it can lead to root rot.

Deadheading & Pruning: Deadheading (remove) and pruning the spent flowers will encourage a long blooming season. Deadheading prevents the plant from using too much energy to produce seed. Pinch back any leggy plants to encourage fuller growth. For more information on deadheading, see The Gardener’s Toolkit-Deadheading.

Spacing & Air Circulation: This prevents fungal issues. When planting multiple rows of zinnias, space them 12 to 18 inches apart. Proper air circulation will help to dry the leaves and discourage fungal and bacterial diseases. For information on zinnia insect and disease problems, see HGIC 2049, Powdery Mildew and HGIC 2110, Zinnia Insect Pests & Diseases.

Zinnia Cultivars

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  ‘California Giant’ zinnias (Zinnia elegans ‘California Giant’) were one of the first zinnia cultivars developed in the 1920s.
  Barbara H. Smith, ©2019 HGIC, Clemson Extension

  Benary’s Giant series has large, double flowers 4 to 5 inches in diameter that range in white and shades of orange, pink, purple, red, salmon, and yellow. The plants are 2 to 3 feet wide and 3 to 4 feet tall.

• California Giant series was developed in 1926. Plants are 3 to 4 feet tall and 2 to 3 feet wide at maturity. The 5-inch flower colors range from bright orange, pink, red, yellow, or white.
• Cupcakes Mix has double, 2-inch flowers that open into powder-puff mounds of cherry, lemon, peach, raspberry, or vanilla hues. They are 30 inches tall and wide.
• Dreamland™ plants are 10 to 12 inches tall and wide. The 3- to 4-inch dahlia-form flowers are available in apricot, coral, ivory, pink, red, rose, scarlet, and mixed colors. This series is more resistant to bacterial (Xanthomonas campestris pv. zinniae) and fungal (Alternaria zinnia) leaf spot diseases.
• Giant Cactus series has spiky, needle-like petals on 4- to 5-inch flowers in an array of colors that range from orange, pink, red, rose, salmon, yellow, and white. It matures at 30 inches tall and is 10 to 12 inches wide.
• Lilliput has double or semi-double 3- to 3½-inch flowers in hues of cream, orange, pink, red, or gold. The plants mature at 12 to 14 inches tall and wide.
• Oklahoma series is a prolific bloomer with 1 ½- to 2-inch semi-double to double flowers in shades of pink, purple, red, yellow and white. It spreads 12 to 18 inches and has a mature height of 30 to 40 inches. It has a higher resistance to powdery mildew. As a cut flower, this series has a long vase life.
• The Magellan™ series has huge 4- to 5-inch double, bright blooms on dwarf plants that grow 9 to 12 inches tall and wide. The flower colors range from cherry, coral, pink, orange, scarlet, yellow, and mixed.
• State Fair Giant series matures at a spread of 12 to 16 inches and a height of 30 to 48 inches. The 4- to 6-inch single, double, and semi-double blooms range from lavender, gold, orange, pink, purple, red, to yellow colors. It was bred to have a higher tolerance of Alternaria leaf spot and powdery mildew.
• Swizzle™ zinnias have beautiful double bi-colored flowers that may be a mixture of cherry and ivory or scarlet and yellow. Due to the 3- to 4-inch multicolored blooms, this cultivar is a showstopper in the garden and is 12 to 14 inches tall and 10 to 12 inches wide.
• Thumbelina Mix is a dwarf, dome-shaped plant that spreads 8 to 10 inches and reaches a height of 6 inches. The small single to semi-double flowers can be up to 2 inches wide and range in various colors from crimson red, lavender, orange, pink, purple, salmon, and yellow.
• Zinderella series has 2-inch show-stopping flowers with a row of petals at the base surrounding a dome of ruffled petals and a center dark eye. It grows 15 to 18 inches wide and 25 to 30 inches tall.

Creeping Zinnia (Zinnia angustifolia) is available in yellow, orange, or white star-shaped flowers.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

Other Zinnia Species

• Creeping or narrow-leaf zinnia (Zinnia angustifolia) has yellow, orange, or white star-shaped flowers and grows 14 inches tall and 8 inches wide. This zinnia does not require deadheading (removing the spent flowers). It has excellent fungal and bacterial leaf spot disease resistance. The compact growth makes this zinnia an excellent choice for borders, bedding plants, and containers. Deer and rabbits tend not to browse this species.
• Mexican zinnia (Zinnia haageana) transplants are unavailable; therefore, planting must be done by seeding. Mexican zinnias are compact growers and grow 12 to 18 inches tall and 12 inches wide. The 1-inch flowers can be single, semi-double, or double, ranging in color from yellow, orange, and red mixtures. ‘Old Mexico’ is one popular cultivar with double to semi-double mahogany-red flowers tipped in yellow. ‘Persian Carpet Mix’ flower colors range from gold, orange, yellow, and burgundy red.
• Zahara series (Zinnia marylandica) is a hybrid cross developed in the 1980s by the University of Maryland. This compact-growing series is disease-resistant and heat-tolerant. The 2 ½-inch double flowers range from orange, pink, red, rose, yellow, or white with pink streaks. The plants have a mounding growth habit and are 8 to 12 inches tall and 12 to 18 inches wide.

Red Profusion zinnias (Zinnia x hybrida ‘Profusion’) form dense, compact mounds and get 14 to 18 inches tall and 20 to 24 inches wide.
Barbara H. Smith, ©2024 HGIC, Clemson Extension

Hybrids

The Profusion series of zinnias (Zinnia x hybrida ‘Profusion’) is a hybrid of Zinnia elegans crossed with Zinnia angustifolia. The mature height is 18 inches with a mounding growth habit. The plants have a higher resistance to powdery mildew and leaf spot diseases. Both the single and double flower forms are available in a wide variety of colors. This hybrid series is also an excellent choice for planting where deer and rabbits are prevalent.

The single flower ‘Profusion’ is available in apricot, cherry, cherry bicolor, fire, lemon, orange, red, white, yellow, sunrise mix, and a 4 color mix.

‘Profusion Double’ is available in double cherry, double deep salmon, double fire, double golden, double hot cherry, double white, double yellow, and double sunrise mix.

Originally published 02/25