This genus includes about 20 annual herbaceous plants, originating in Mexico and Central America. Zinnias grown as ornamental flowers are hybrid species derived from Z. elegans. These plants form thick erect, branching bushes, with oval leaves, dark green and large solitary daisy-shaped flowers, simple and double. The flowers of zinnia they exist in all colors except blue. It is also possible to find two-colored and mottled varieties. The size of the bush varies, depending on the variety, from 30 to 120 cm. To prolong the flowering of this variety it is necessary to remember to remove the withered flowers.
The zinnia flowers, for an ideal exposure, need to be planted in full sun, even if they tolerate a few hours of shade a day; to have a good flowering they must be able to receive a few hours a day of sunshine. They love hot summers very much, they absolutely do not tolerate the cold and, for this reason, the zinnia it is cultivated as an annual species. In choosing the position in which to plant the le zinnias remember to choose a well-ventilated place, to avoid the appearance of fungi or molds that would irreparably compromise health and growth.
Thinking about how much water it is necessary to supply to the zinnia, it is good to know that the plants belonging to this variety do not need large amounts of water, resisting well even to short periods of drought. It is advisable to water regularly, especially during the hottest period, with modest amounts of water, waiting for the soil to dry well between one watering and another. These plants fear the formation of water stagnation, which can cause the onset of mold and fungal diseases.
Provide fertilizer for flowering plants every 15-20 days dissolved in the water of the watering to have a more abundant flowering.
These varieties grow without problems in any garden soil, however, preferring loose, well-drained soils rich in organic matter. When you decide to plant the zinnia it is good to prepare a mixture that is soft and drained, mixed with organic fertilizer, in order to provide all the necessary nutrition to the plant.
The multiplication of this kind of flower occurs by seed, using the seeds of the previous year at the end of winter. From February to April the seeds are sown zinnias keeping the seedbeds in a protected place to prevent abrupt thermal drops from compromising their development; the new plants are planted in April-May, paying close attention to the roots of the seedlings, which are very delicate. Wishing the zinnias can also be sown in the ground in May, when it is certain that the temperatures remain mild and there is no risk of late frosts.
Zinnia: Pests and diseases
The plants belonging to this variety are rather resistant to the attack of pests and diseases but, under certain environmental conditions, they can be attacked by scale insects. For this reason it is good to think of practicing a specific pesticide treatment that will guarantee the right protection for such specimens.