Lobelia erinus. Vivid navy blue flowers adorn this tiny, trailing Lobelia, making it ideal for stuffing between other plants as a ground cover. The flowers are highly attractive to bees and butterflies. Grow Midnight Blue Lobelia seeds in window boxes or hanging baskets, and allow it to cascade over the edges of any container. In moist soil it will thrive in full sun or partial shade. This trailing Lobelia looks fabulous with Alyssum, and fills in empty corners really well. Sow the tiny, dust-like seeds on the surface of moist soil, and do not transplant outside until night time temperatures are well above 10°C (50°F).