How to Grow and Care for Zinnias
About Zinnia
Zinnia (Zinnia elegans) grows 1 to 3 feet tall and is hardy in USDA zones 2 to 11. It grows best in full sun to part sun with medium water.
A lovely butterfly and hummingbird attractor, Zinnias are annuals in the Asteraceae family, native to Mexico, and grows from 1-3 feet tall, with some dwarf varieties only 6″, and others reaching 4 feet. Arranged oppositely clasping to its hairy stem, leaves are ovate to lanceolate in shape, reaching 5 inches in length. Almost every cultivar is a great cut flower, lasting up to 2 weeks in a water vase. Zinnia elegans honors Johann Gottfried Zinn (1727-1759), a German botanist and ophthalmologist, and human anatomy professor from Gottingen University. The particular epithet means elegant, and indeed it is, with 7-20 ray petals reaching 3″-6″ in diameter, blooming throughout summer and into Fall, in varied shades of yellow, pink, red, lavender, orange, green and white. Traditionally, natives would feed the plant to their children for improved mental and physical health. Current science articles point to Zinnias’ properties of being antibacterial, anti-fungal, anticancer, and other.
When to Plant Zinnias
Sow zinnia seeds directly in the garden after the last frost, once the soil is warm. Sow again every few weeks for continuous flowers.
How to Plant Zinnias
Zinnias are so easy to grow! They do well in USDA zones 2b-11b, and do can handle soil pH of 6.0-8.0. Seedlings can be purchased from a nursery, but look for disease resistant cultivars. Plant in Spring after last freeze, into well-draining, rich organic soil in full sun. Seeds can be planted from center of spent flower, into rich, well-draining soil. To ensure earliest bloom, plant seeds directly into rich soil, or indoors 4 weeks before last frost date, then transplant as seedlings.
Zinnia Care
Do not over water! Taller stems may benefit from staking, but they often use each other to stay aligned, proving peer pressure can work. Allow soil to dry between watering. Zinnias do well in planters or mass plantings, large garden area or small, as long as it’s in full sun.
Fertilizing Zinnias
A general 10-10-10 fertilizer is beneficial but not necessary. Follow package descriptions.
Pruning Zinnias
Deadheading (removing spent flowers) will encourage more blooms. This will also allow better air circulation and thus will prevent mildew issues.
Zinnia Pests and Diseases
Overwatering provides a perfect environment for harming Zinnias: powdery mildew, leaf spots, root rots, blight and Botrytis. Avoiding overwatering generally means avoiding these diseases. Japanese beetles sometimes attack Zinnias.
Are Zinnias Toxic to Cats and Dogs?
No. The ASPCA lists zinnias as non-toxic to dogs, cats and horses. If you think a pet has eaten a toxic plant, call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435.
Zinnia FAQs
How long do zinnias take to bloom?
Most zinnias bloom 60 to 70 days after sowing and keep flowering until frost.
Do zinnias come back every year?
No. Zinnias are annuals, but they are easy to regrow from seed each spring.
How do I prevent powdery mildew on zinnias?
Space plants for good airflow, water at the base in the morning and choose mildew-resistant varieties.
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