Great Blue Lobelia thrives in consistently moist soil. Water regularly, especially during dry spells, to maintain even moisture. Avoid allowing the soil to completely dry out, as this can stress the plant.

Deep watering is preferable to frequent shallow watering.

Deadheading spent flowers can encourage reblooming and improve the plant's appearance. In late autumn, after flowering has finished, cut the plant back to the ground.

This tidies the garden and helps prevent disease overwintering.

Great Blue Lobelia can be easily propagated from seed sown in early spring or in autumn. Division of established clumps in spring is also an effective method. Ensure new divisions have adequate moisture.

Repotting is typically only necessary for container-grown specimens. Move to a slightly larger pot every 2-3 years in spring if the plant becomes root-bound.

Use a well-draining potting mix and water thoroughly after repotting.