Marsh dandelion is a recent introduction to North America, and only occasionally found in New England (Connecticut and Vermont). It disperses mostly in ditches along roadways. The introduced dandelions originate mostly in Europe, where the number of species and species boundaries are in dispute.
Water occasionally. Water throughout the summer months, about once a week or more during periods of drought, but let off once fall approaches.
Dandelions grow best with a full day of sunlight. If you want to grow them indoors, plan for their growing lights to be on 14 to 16 hours per day. Using full-spectrum lights or pairing light bulbs to create full-spectrum light is best for dandelions.
Seeds germinate throughout the growing season when soil is moist and soil temperature is at least 50°F. However, germination is more rapid when the soil temperature is closer to 77°F.
The container for growing dandelion plants indoors should be at least 6 inches (15 cm.) deep to accommodate the long roots. The width of the container depends on how many plants you intend to plant and how large you want them to be at harvest. A 4- to 6-inch (10-15 cm.)