Tithonia diversifolia requires consistent moisture, especially during dry periods and its active growth and flowering phases. Water deeply 2-3 times per week in hot, dry weather, ensuring the soil is moist but not waterlogged. Reduce watering once established and during cooler periods, but never allow the soil to completely dry out.

Prune Tithonia diversifolia to encourage bushier growth and more flowers. Pinch back young plants to promote branching. Deadhead spent blooms regularly to prevent self-seeding and extend the flowering period. Cut back plants by about one-third in mid-summer if they become leggy or overgrown.

Mexican Sunflower is easily propagated from seeds, which can be sown directly outdoors after the last frost or started indoors 4-6 weeks prior. It can also be propagated from stem cuttings taken in late spring or early summer. Cuttings root readily in water or a moist potting mix.

Due to its large size and rapid growth, Tithonia diversifolia is not typically grown as a long-term potted plant. If starting seeds indoors, transplant seedlings into larger pots as they grow, then move them to their final outdoor location once frost danger has passed and they are well-established.