Available in several varieties, the zinnia (Zinnia) is found U.S. Department of Agriculture hardiness zone 9 through 11. Like many other flowers, zinnias will not grow without the proper environment and require protection, even after germinating, from several environmental threats. Without your vigilance, several possible factors could cause problems with your zinnias before they even have a chance to bloom.
Planting zinnias at the wrong time of year can cause the seed or seedling considerable trauma and can prevent germination or the establishment of the plant. Make sure the weather is mild and that the ground is not too cold. If planting zinnias in early spring, ensure that the temperature hovers between 65 and 55 degrees Fahrenheit. For colder areas, plant zinnias in late spring when they can take advantage of the warmth of imminent summer.
Blooms produced by zinnias require a great deal of energy from the plant. Because of this, zinnias thrive best in full sunlight, requiring six or more hours per day. Too little sunlight for too long will prevent new zinnias from germinating and seedlings from developing.
Zinnias are naturally resistant to drought once established, but first they will require moist soil rich in nutrients to germinate and establish themselves. Loam, a mixture of silty, peaty and sandy soils provides adequate nutrition and moisture while draining well enough to avoid drowning the new plant. Ensure your plant is in rich, loamy soil and that multiple plants are spaced 6 to 18 inches apart depending on the species. This will allow the zinnias enough soil area for maximum nutrition.
More than just the source of a zinnia’s hydration, water is also the purveyor of all the soil’s nutrients, delivering nitrogen, potassium, calcium as well as several other elements crucial to photosynthesis. Keep zinnias well-watered during planting and seedling stages, but avoid drowning the plant. Test the soil by pressing down on it with your fingers. If significant water presses up from the soil, then it is too wet; if the soil sticks to your fingers with moisture but no visible puddle forms, then the soil is properly moistened.
Fungal infection can reach new zinnias in the soil or through the air. Brown spot, powdery mildew and southern blight are all caused by fungi. Once infected, young zinnias are likely forfeit, so remove and destroy infected plants to avoid the spread of fungal spores.
Zinnias are more susceptible to pests during the initial stages of their growth than when they are established. If developing zinnias show signs such as dropping leaves or shriveling, check for pests including caterpillars, mealybugs and spider mites. Spraying developing zinnias with an insecticidal soap can reduce the risk of pest infestation. Make sure your insecticidal soap does not harm beneficial insects such as bees.
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