How to Grow a Lobelia from Seeds
Not only is lobelia popular for their bright white, red, purple and blue flowers, but they are remarkably easy to grow and maintain from lobelia seeds. They are also known for being able to grow in just about any climate, so long as there isn’t any snow on the ground when they’re planted. When growing from seed, you can choose the easiest route, which is simply scattering the seeds around the garden. This will usually produce results, but you aren’t guaranteed good flower positioning or control. For more control, consider sowing your lobelia in seedling trays.
Step 1 – Sowing the Seeds
The seeds for lobelia are extremely small. To plant them, fill a seedling tray most of the way with vermiculite growing soil and sprinkle the seeds thoroughly across the top. After sprinkling seeds, fill the tray the rest of the way with loose vermiculite soil and lightly tap it down to remove any air pockets.
Step 2 – Germinating Seedlings
Cool to moderate temperatures indoors are fine for growing. They like constant moisture, but not a great deal of water. It is best to keep the soil moist by misting with water on a daily basis. If the seeds get too much water, they will become soggy and will have to fight harder to grow.
It will take about 3 weeks for the seeds to germinate into seedlings, after which you’ll need to start giving them light. Use moderately bright grow lights, or set them where they’ll get filtered sunlight every day.
Step 3 – Transplanting to Pots
As the seedlings continue to grow, you’ll want to pluck out the smaller, weaker ones. This will help the larger ones to stay stronger and healthier. Once they have reached about 2 inches or so, you can transplant them to small growing pots, about 2 inches in size. Continue caring for them as you have been until they are about 3 or 4 inches tall.
Step 4 – Hardening off Lobelia
Hardening is the process of getting your indoor plants used to a new, outdoor environment. Unlike many other plants, lobelia doesn’t necessarily need hardening off, especially in moderate climates where there isn’t a great change between their outdoor and indoor environments.
To harden them off, begin taking them outside about a week or two before you plan to transplant them. Leave them out for only an hour or so and in the shade for the first day, and gradually increase the length of time they’re out each day. You can also increase how much direct sun they get each day, if you like. The idea is that they can comfortably sit outside all day long by the end of the hardening period.
Step 5 – Transplanting Outside
After they have been hardened off, they are fully ready to be transplanted outside. Be sure that the threat of frost is over with first. You can choose a location with either direct sunlight, shade, or a mixture of both. Space them at least 4 inches apart, or more depending on your particular species of lobelia. Water them at least once a week with a minimum of 1 inch of water, and spread mulch over the soil to conserve moisture, as drying out is the easiest way to damage or kill lobelia plants.