Start seeds indoors 4-6 weeks before the last expected frost date. Sow seeds about 0.5 cm (1/4 inch) deep in seed starting mix. Maintain moisture and warmth (21-24°C / 70-75°F) for germination, which typically occurs in 5-7 days. Provide strong light after emergence.

Alternatively, sow seeds directly into garden beds or containers after all danger of frost has passed and the soil has warmed. Plant seeds 0.5-1 cm (1/4-1/2 inch) deep. Keep the area moist until seedlings emerge.

For seedlings started indoors, gradually acclimate them to outdoor conditions over 7-10 days before transplanting. Increase exposure to direct sunlight and outdoor temperatures incrementally.

Plant hardened-off seedlings or nursery-bought plants into their final location after the danger of frost has passed. Space according to variety (typically 15-45 cm / 6-18 inches). Plant at the same depth as they were in their previous container. Water thoroughly.

Water regularly after planting until established. Mature marigolds are relatively drought-tolerant but bloom best with consistent moisture. Allow the top layer of soil to dry slightly between waterings. Water at the base of the plant to keep foliage dry.

Marigolds thrive in average soil and generally do not require heavy feeding. Excessive fertilizer, especially nitrogen, can lead to abundant foliage with fewer flowers. A light feeding with a balanced fertilizer mid-season is optional if growth appears slow.

Remove faded and dead flower heads regularly throughout the blooming season. This practice, called deadheading, encourages the plant to produce more flowers instead of putting energy into seed production and keeps the plant looking neat.

While generally robust, marigolds can occasionally attract spider mites, especially in hot, dry conditions, or develop fungal issues like powdery mildew in humid weather with poor air circulation. Check plants periodically.