Zinnia elegans hybrids are fast growing annuals whose original species are native to Mexico. Zinnias today have a myriad of colors, flower form, as well as heights. Different cultivars range from 8 inches (20 cm) tall to 3 feet (0.9 m) tall. All forms have a common leaf shape of lanceolate, ovate or oblong. In the greenhouse, we use zinnias for our "Plant Care and Cultivation" classes and for IPM (Integrated Pest Management) experiments for Ecology class. Their ease in cultivation gives student fast flowering from seed.
Blooming: In the greenhouse, the plants will bloom all year long. Flowers come in single and double forms and sizes. Flowers range from 2 inches (5 cm) to 5 inches (13 cm) across.
Culture: Zinnia elegans hybrids need full sun to light shade with a rich well drained soil mix. In the greenhouse, we use a soil mix consisting of 2 parts peat moss to 1 part loam to 1 part sand or perlite. For each 0.01 cu. yards of soil mix, we add 1 cup of 14-14-14 osmocote slow release fertilizer, 1 cup hydrated lime to adjust pH and 1 teaspoon of micromax micronutrients. This gives the soil mix a pH of 6.5 and enough nutrients to grow and flower quickly. The plants are well watered and allowed to dry slightly before watering again. In the landscape, zinnias are fairly drought tolerant, but less so in containers. The only problem with growing them in the greenhouse is that aphids can become a problem, which is why we grow them for IPM experiments. If plants are kept deadheaded, the flowering period is extended. At the end of classes, we collect the seed for the next set of classes, and the plants are allowed to die off. When growing in the winter months, supplemental lighting is needed.
Propagation: Zinnia elegans hybrids are best propagated from seed. Seed germinates in 7-14 days from sowing.
Zinnia elegans was featured as Plant of the Week November 2-8, 2007.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.