For The Answer
By Calvin Finch, Ph.D., Director of Conservation, SAWS, & Horticulturist
Submitted to the Express News
Zinnias are one of the best annual flowers for use in San Antonio. They are colorful, attract butterflies and are not eaten by the deer. Some of the selections make good xeriscape plants and some are wonderful cut flowers.
If you grew up in the North you probably seeded zinnias in May and enjoyed the blooms from June through September. In San Antonio the growing practices are somewhat different. We seed or use transplants in March and enjoy the blooms of these plants through early summer when mildew and heat reduce the production to the point that they are relegated to the compost pile.
At that time you can plant new transplants or rely on the reseeded plants that always show up in the zinnia bed if the seed can reach soil. These naturalized plants are quite often not exact duplicates of your original stock but they are colorful and free. Even the hybrid zinnias are excellent hummingbird and butterfly nectar sources but the parent stock plants that reseed are even better. Tolerate the looser, less compound petals because of the superior nectar production.
Dreamland is the usual transplant available at area nurseries, it seems to have better mildew resistance than thumbelina, cactus, lilliput, California giant, dahlia and others that we get in seed pockets, but all work for short season bloom. Zinnias are available in white, red pink, yellow and bicolors in various patterns. Dreamland planted 18 inches apart in rows 18 inches apart will make a great show.
Zinnias benefit by mulch and drip irrigation but if the mulch is deep and extensive the reseeding I described, will not occur. One strategy is to mulch near the plants but leave an area of bare soil in between the rows. Discard the deadheaded flowers on the bare soil. If the area is irrigated the naturalized plants will quickly fill in.
Deadheading, the process of removing spent blooms is essential if you want to extend the bloom period and maximize attractiveness of the bed.
The annual zinnias such as Dreamland can tolerate heat but they are not xeriscape plants in terms of water. They require irrigation every 2 or 3 days to stay in top performance. Some new entries on the market however, are less water sensitive.
Profusion is a landscape zinnia that forms a mound about 16 inches high and 24 inches around. It has relatively small flowers (half-dollar size) in two colors, pink and golden yellow. I prefer the golden yellow because the pink fades in the San Antonio sun. If Profusion is mulched and established it can go 2 or 3 times as long as the regular zinnias between waterings. Deadheading is not required for Profusion.
Zinnia linearis is the xeriscape zinnia. Its white daisy like flowers are even smaller than Profusion but it can bloom with watering every 2 weeks. Use it for color in the perennial bed. Deadheading is not necessary.
All zinnias require full sun and all are rejected by deer as a food source. Use the zinnias for spring, summer, and fall color in neighborhoods with the pesky animals.