Dahlia imperialis prefers consistently moist soil during its active growing season. Water deeply when the top 2-3 cm of soil feels dry. Avoid waterlogging, which can lead to root rot.

Reduce watering significantly in autumn as the plant begins to decline, allowing the soil to dry out between waterings.

Deadheading spent flowers regularly encourages more blooms and maintains a tidy appearance. Cut back the main stem after the final flush of blooms in autumn to prepare for winter dormancy.

In spring, prune away any dead or damaged growth before new shoots emerge, and consider pinching back young shoots for bushier growth.

Dahlia imperialis is typically propagated by division of its tubers in spring before new growth appears. Carefully separate the tubers, ensuring each piece has at least one eye or bud.

Alternatively, stem cuttings can be taken in late spring or early summer, rooted in a moist medium, and then planted out.

As Dahlia imperialis grows into a large specimen, it rarely requires repotting in the traditional sense. If grown in containers, select a very large, sturdy pot.

The primary 'repotting' activity involves lifting and dividing the tubers annually or every few years in spring when they are dormant.