Marshmallow thrives in consistently moist soil, especially during its active growing season. Water deeply when the top few centimeters of soil feel dry to the touch, ensuring the roots receive adequate moisture. Avoid waterlogging, but do not let the soil dry out completely for extended periods, particularly in hot weather.

Pruning is not strictly necessary but can help maintain plant shape and encourage bushier growth. Deadhead spent flowers to prevent excessive self-seeding and prolong the blooming period. In late autumn or early spring, cut back old stems to the ground to make way for new growth.

Marshmallow can be propagated by seed, division, or stem cuttings. Seeds can be sown directly outdoors in spring or autumn, or started indoors. Division of established clumps in spring or autumn is a reliable method. Softwood cuttings can be taken in early summer.

As a perennial grown outdoors, repotting is not typically applicable unless grown in containers. If container-grown, repot every 2-3 years into a slightly larger pot with fresh potting mix to refresh nutrients and accommodate root growth. Ensure good drainage.