As an annual, USDA climate zones are of little relevance to dwarf marigolds since they die back each autumn with or without heavy frost. However, to maintain their health and attractive appearance, dwarf marigolds should be grown in warm, sunny climates with low humidity. While not devastating to dwarf marigolds, humidity will increase their likelihood of developing botrytis grey mold, which will negatively affect the look and general health of the plants.
Dwarf marigolds, or Tagetes patula, appeal to many gardeners with their cheery golden flowers, petite stature and innate hardiness, which makes them suitable for border plantings and container cultivation. Although dwarf marigolds will survive under a variety of conditions, their climatic and cultural adaptations must be provided for if they are to truly thrive.
The soil adaptation of dwarf marigolds must be taken into consideration when planting them since they will not survive for long in soggy soil. Although they are not picky about soil composition, it is wise to amend the soil in their permanent bed with compost and sand to increase its drainage and short-term moisture retention, which will decrease the need for frequent watering.
Like all marigolds, dwarf marigolds require little water and are highly drought tolerant. However, they will look and grow best if provided with supplemental water during periods of prolonged drought. Apply water only when the edges of the leaves begin to wilt slightly. Water slowly, allowing the moisture to seep into the soil before adding more. In addition, it is best to water at the base of the plants instead of spraying from above since excess moisture on the foliage will increase the likelihood of the plants developing botrytis grey mold.
Dwarf marigolds are sun lovers and require full exposure to sunlight throughout the day. Southern exposure is best for dwarf marigolds since it provides them with greatest amount of direct sun, but they will also grow well with western exposure as long as they aren't shaded. Shade will diminish the attractive appearance and long term vitality of the plants, so they must be planted away from overhanging trees and structures to keep them healthy.