The various cultivars of Lobelia erinus are grown as edging and container plants. When grown in hanging baskets, they have a cascading form. Lobelia erinus is an annual plant, native to South Africa, and like most annuals, it blooms all summer and reproduces by seed. Seed germination is the moment when the seed stops being inert and begins to produce a new plant.
Flowers exist to reproduce plants. Fertilization occurs when pollen from the flower one plant in a species is deposited in the flower of another. The shape, color and scent of the flower lures various pollen carriers, usually insects, to move from one flower to the next. After the flower is pollinated, the flower withers and dies off, while the plant produces a seed. Annual plants like lobelia continue producing more flowers throughout the growing season, increasing their fertilization rate.
Parts of a Seed
All seeds contain the embryo, which will grow into a new plant. Most seeds also contain endosperm, a tissue that stores food for the embryo, and testa, the seed shell. Some seeds also contain other specialized structures, but Lobelia erinus seed does not.
When the embryo begins to grow, it first uses up the food stored in the endosperm. It then cracks through the testa, and its cotyledons, a pair of tiny leaves, are visible. If the newly germinated seed continues to grow, it will soon develop the real leaves and roots of a plant.
Conditions for Germination
Seed embryos begin to grow partly because of their genetic impulses and partly when environmental conditions are favorable. Annual plants, like the lobelia, germinate, grow, flower, set seed and die in one season, with the seed having a dormant period between one growing season and the next. Perennial seeds can remain dormant for several years, or even decades, before germination. Some species require special treatment before they will germinate, such as a cold period, a weakening of the testa, or the presence of specific levels of light, dark or moisture.
Conditions for Lobelia Germination
Lobelia erinus seeds usually need to experience favorable conditions for 14 to 21 days before they germinate. They should be sown on the surface of the soil, because they require light to germinate. They prefer temperatures of 65 to 75 degrees F and an evenly moist environment. The seedlings take eight to 12 weeks to grow large enough to transplant, and they should not be planted outdoors until after the last frost.