Annual zinnias are a colorful and easy to grow flowers. They have the classic “daisy” flower shape but this can be complicated by double or more layers of petals so they can also be rounded in shape. They are native to Mexico and Central America but have been hybridized a lot and many varieties are now available, especially if planting from seed.
Seeds can be planted a month or 2 before the last frost indoors or seeds can be planted directly in the ground. They like well drained soil and full sun. Most garden centers carry flats of young plants in late spring. Mostly zinnias are annuals but at least 2 perennial types exist as well. It is easier to find the variety that meets your needs if planted by seed and zinnias are truly easy to grow from seed so they may be a good first plant to try this method with. Zinnia seeds are large enough to pick up individually and have little hooks on the end to aid in their dispersal in nature. It doesn’t matter which way they lay when you plant them. The main point is they are big enough for little hands to hold. This together with their ease in growing, quick return of flowers and colorful nature make them a good seed for a child’s garden.
When growing zinnias one should decide what one’s main purpose in growing them is. Are they to be landscape plants, providing color in the yard. If so are they in the background (grow 2 to 3 foot varieties), middle (18 inch varieties) or foreground &/or containers (tiny 4 – 8 inch varieties also exist. Or, are they for to be used mainly as cut flowers? What color(s) do you want? They are available in every color but blue. Yes, even green, that variety is called “envy” and it is quite the cool little gem. It even tolerates a bit a shade.
If you want to use them for cut flowers they should be cut while still in their prime. Even if you don’t want to bring flowers indoors, they should be deadheaded when the flower begins to fade to induce more flowering. Cut back to where the stem began. Most annual zinnias make great cut flowers because many have longish and strong stems. They last about a week in a vase and they are very colorful. Like most annuals they also bloom more if frequently deadheaded. In fact zinnias are notorious for their prolific re-blooming habits, as reflected by the names of varieties such as “cut and come again” and “profusion”. They mix well with other cut flowers or look nice alone. Zinnias are a favorite in my area for Farmers Markets and kids’ road side stands.
Zinnias are plagued by some diseases, especially in areas with humid summers. The worst is powdery mildew. This causes a white powdery stuff to appear on the leaves, especially the lower leaves mid to late summer. Luckily it doesn’t really affect the flower head, just the leaves. The leaves can just be removed and flower arranging can proceed. Once powdery mildew ensues the plant will continue to flower, albeit at a slower rate. Since it is an annual, the best thing to do is to work toward preventing the mildew. Do this by allowing air circulation around the plants, don’t overcrowd them. Plant them in full sun. Also, as much as possible, don’t get the foliage wet when watering and water in the morning (only when needed, don’t over water) so the foliage will dry during the hot day light hours. Throw the diseased leaves and eventually the old plants away, don’t compost them or leave them in the ground over the winter. Rotate where you plant zinnias. In my opinion one shouldn’t bother spraying for the disease. It appears late enough in the season that the plants are almost done for anyway. If you REALLY love zinnias begin some replacement plants in early to mid summer for the fall bloom. The mildew mostly attacks older plants. Some newer hybrids are more resistant to mildew.
Butterflies love zinnias, especially the mid to large sized single varieties. They can land on their flat surface easily and the nectar holding center bits are more abundant and out in the open.
My personal favorites:
Zinnia ‘Pinwheel’ and Zinnia ‘Thumbelina’ for bedding plants
Zinnia ‘Envy’ for fun
Blue Point zinnias in multiple colors for cutting garden
Zinnia angustifolia ‘Star White’ for containers
There are at least 2 perennial zinnias I just learned about. “Native to the Southwest are … desert zinnia (Z. acerosa) and plains zinnia (Z. grandiflora). Desert zinnia bears 1” white, daisylike flowers on a low, spreading plant. Narrow leaves are evergreen, making Z. acerosa a good ground cover. It prefers well-drained soil that is low in organic content. Plains zinnia, with a similar growth habit, has yellow flowers. It is more tolerant of cold, but it can be difficult to establish.”
Live and learn plus quote and a few scattered factoids from