A Complete Guide to Geranium Care in Autumn

After the scorching summer, geraniums in a semi-dormant state begin to gradually revive, growing new leaves and blooming again, adding color to the golden autumn. However, geraniums that have just made it through the hot summer inevitably suffer from old roots and declining leaves, with weak growth. The newly emerging leaves are small and dark green, the petioles and flower stalk stems are rather short, the flower heads are small, and the overall plant shape is clumped, reducing its ornamental value. Treating geraniums with gibberellin can effectively promote lush leaves and abundant flowers, improving their ornamental value. The method is as follows: after the geranium plant resumes growth following the summer, when the flower stalk stems of the first batch of flowers change from curved to upright, that is, when the newly sprouted branches have unfolded 3 to 4 leaves, spray the entire plant with a 500 ppm gibberellin solution, just once. This method is not only suitable for perennial old plants, but is even more effective when applied to cuttings from the same spring. After treatment, the petioles grow 10 to 12 cm, compared with 5 to 7 cm for the control; the flower stalk stems grow 15 to 20 cm, with the longest reaching 24 cm, compared with 7 to 10 cm for the control; individual flower stems grow 3 to 5 cm, while the control is only 2 cm. Petal length can increase by 0.5 cm, and width also increases somewhat, but their shape, number and color are all unaffected. The leaves turn noticeably tender green, with basically unchanged size.

Because geraniums belong to the umbel or cyme type of inflorescence, the small flowers are numerous and overlap in clusters to form a spherical flower head. The size of the flower head does not depend on the number of flowers, but mainly on the size of individual flowers and the length of the flower stems. After treatment, because the individual flower stems lengthen, the flower head becomes noticeably larger. For some varieties belonging to the cyme type, such as Purple Hydrangea and Foreign Lotus, the flower head diameter can reach 15 cm or more, with the largest reaching 20 cm. For some varieties belonging to the umbel type, such as Peach Blossom Face and Danlu Pink Lotus, because there are no secondary flower stalk stems, the flower head increases less, but can still reach 10 cm or more. In addition, because the flower stalk stems lengthen most noticeably (generally 1 to 1.5 times that of the control), the flower heads tower above the leaf cluster, elegantly upright and very bright and eye-catching, making them even more suitable as cut flowers.

The only drawback of treating geraniums with gibberellin is that the branch tips become thinner and weaker, and the branches that continue to grow have sparse leaves and thin stems, making the plant tend to become loose. The adjustment method is as follows: within one week after treatment, cut off the thin, weak shoot tip above the flower head, leaving one leaf, and a well-developed lateral bud in the axil of the first leaf below the flower head will sprout and grow a branch. Because this lateral bud sprouts one week after the gibberellin treatment, it is unaffected, so the branch that grows is as thick and strong as before. When the treated flower head is in full bloom, this new branch has also already formed buds, and can still be treated once more with gibberellin. Repeating this process will make the geranium's flowers abundant and leaves lush, greatly increasing its ornamental value.