Marigolds (Tagetes spp.) are great for butterfly gardens. Double-bloomed varieties can hold water between the petals, allowing thirsty butterflies to take a drink when they stop for some nectar from these colorful flowers. You can start marigolds from seed indoors roughly 8 weeks before you’re planning to transplant them outside. Park’s Whopper Mix or Marigold ‘Tiger Eyes’ are both good varieties to consider. Most cultivars are hardy in Zones 2 – 11.