Lobelia is a great border annual that will grow in almost any garden zone and at almost any time of the year (except under a pile of snow). In fact most gardeners, and those who for one day called themselves a gardener as they replanted their store bought seedlings, have planted lobelia at some stage in their gardening journey. The more avid gardeners would have taken this a step further and planted lobelia from seed.
Lobelia’s are wonderful little annuals with striking whites, red, purples and blues they can contrast or complement your planting schemes without too much fuss. They don’t require much fertiliser, maybe just an application of a liquid fertiliser every 4-6 weeks through their flowering period, and regular watering are all they require. You don’t need to deadhead or prune them and they will reward you constantly for your lack of effort.
There are many varieties of lobelia but the most common ones are Lobelia cardinalis (scarlet variety), L. siphilitica (the great blue) and L. inflata (commonly known as Indian Tobacco). Lobelia inflata is a common herb well known to naturopaths because of its many medicinal benefits. It is used predominantly dried for many phlegm-related respiratory conditions including asthma and bronchitis. It is also a common ingredient in natural anti-smoking products. It’s not a common garden plant though.
The other two types of lobelias are very common in the garden and easy to grow from seed.
How to grow lobelia from seed.
There are two ways to grow lobelia from seed. Firstly, you could scatter the seed in the area that you wish for them to grow or you could raise them in seedling trays. Raising them in seedbeds is the best way to get uniformity of plant and also you are more able to control exactly the position that they will grow in.
The first option is by far the easiest and less time-consuming while the latter takes considerably more time and effort but there is more enjoyment and it’s an easy seed to learn how to propagate.
To sow Lobelia in seedling trays.
If you decide you want to grow them in seedling trays, fill the tray completely with a seed-raising mix and shake the tray until the mix settles. This should leave a gap of a couple of millimetres for you to plant the seed. Plant 2-3 seeds in each punnet or if you are just using a straight seedling tray then cover the top of the soil with your packet of seeds. Cover these with another thing layer of seed-raising mix and tap down to remove any air pockets.
Water with a demister as too much water will make your seedlings struggle. Store them in a place where they can receive some filtered light and warmth.
As your lobelia seedlings begin to appear above the top of the soil, pinch out the extra ones leaving the strongest ones to continue growing. The seedlings will begin to appear within 7-10 days of potting and you should pinch them out within a couple of weeks of them sprouting. If you leave them too long it will be harder to separate the seedlings.
Once they have grown to a size of about 5cm and have produced at least 2 normal leaves they will be ready to plant out into the garden. Remove each plug and transfer into the soil watering in with a soluble fertiliser and sprinkling a ring around them to stop snails enjoying your new seedlings.
You will start to see your new lobelias begin to flower within 10-12 weeks.