Bright blue flowers brighten up any garden, especially those in full or partial shade. Lobelia’s pure blue flowers provide a nice contrast to the many shades of green in foliage-rich shade gardens. Or plant them so they hang over the edges of containers and hanging baskets. Start seeds indoors eight to ten weeks before frost-free weather is expected in your area.
Start your lobelia seeds in flat, shallow pans. Fill them with either a commercial seed-starting mix or make your own by combining equal parts of peat moss and vermiculite.
Sow seeds by sprinkling them over the surface of the seed-starting mix. Press them into the mix lightly and do not cover; they need light to germinate.
Mist the surface with water using a plastic spray bottle. Mist the seeds daily until they germinate, which should take about three weeks.
Move the seed-starting trays under fluorescent lights as soon as they germinate. Position the lights so they are about 3 inches above the tops of the seedlings. Raise the lights as the seedlings grow taller, keeping the lights at least 3 inches above the tops of the plants.
Keep the seed-starting medium damp by misting it every day with a plastic spray bottle.
Transplant little clumps of lobelia seedlings into individual, 2-inch pots filled with regular indoor potting soil. Continue watering to keep the soil, moist but not wet.
Acclimate the plants to outdoor conditions when they are about 3 to 4 inches high. Put them outdoors in shade for a few hours each day and bring the plants indoors at night, or if daytime temperatures are below 50 degrees F.
Transplant your lobelia into the garden when all danger of frost has passed. Plant lobelia in partial shade, placing the individual clumps approximately 10 inches apart.