Annual Mercury prefers consistently moist soil but can tolerate brief periods of dryness. Water thoroughly when the top centimeter of soil feels dry to the touch. Avoid waterlogging, as this can lead to root rot.

Reduce watering frequency during cooler months or when the plant is dormant.

Pruning is typically not necessary for Mercurialis ambigua unless aiming to control its spread or remove any damaged or spent foliage. Light trimming can be done in late spring or early summer to maintain shape or prevent overcrowding, but the plant generally self-manages its size.

Mercurialis ambigua readily self-seeds, making propagation simple. Collect seeds in late summer or autumn and sow them directly in the desired location or in pots.

Alternatively, division of established clumps can be done in early spring before new growth emerges.

As an annual plant, Mercurialis ambigua is not typically repotted. It completes its life cycle within a single growing season.

If grown in containers for aesthetic purposes, it is best to treat it as an annual and replant each year with fresh seedlings or seeds.