The name “geranium” is based on a Greek word meaning crane. It was given to the plant because of the shape of the schizocarps, the seed pods, which resemble the bill of a long crane.
Geraniums can be annual, biennial or perennial. Their flowers can be single, double or semi-double. They grow best in full sun and will tolerate most soil conditions, but they do not like their roots to stay wet too long.
To keep them flowering continuously throughout the summer, you will need to keep them dead-headed. Dead-heading is the removal of spent flower heads as they begin to deteriorate. This will prevent the plant from going to seed and force it to produce more blooms.
Geraniums do have their share of problems with disease and insects. One disease is bacterial leaf spot. This disease is especially prevalent in warm, wet weather and when plants are grown in crowded conditions. Symptoms include small, circular or irregular brown sunken spots on older or lower leaves. Large numbers of spots will occur on a single leaf, and these will combine to kill a large portion of the leaf, which will then drop off. Leaves infected with bacterial leaf spot should be removed immediately. Heavily infected plants should be removed.
Another common disease of geraniums is a fungus known as botrytis leaf spot or botrytis blossom blight. Botrytis occurs under cool, moist conditions or when plants are watered frequently, particularly from overhead. Leaves develop brown lesions that then develop into a grayish-brown mass of fungal spores. The lower leaves will turn yellow and rot. Flowers may also become infected and display discolored petals, which eventually wilt and fall. All affected leaves and flowers should be removed.
• UC Certified Master Gardeners are available to answer your gardening questions Tuesdays, Wednesdays, and Thursdays from 9 a.m. to noon at 953-6112 or at mgsanjoaquin@ucdavis.edu. Questions for Heather Hamilton can be submitted to ucmastergardener@gmail.com.
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