When you grow tropical plants in cold climates you have to decide if you want to overwinter them or let them die and start over again come spring.
Impatiens niamniamensis is a tropical plant that hails from Africa.
Ricinus communis or Castor Beans as they are commonly called are easy to start from seed each spring.
Cannas are easy enough to grow indoors provided they get plenty of light, but honestly it is easier to dig the rhizomes once the foliage dies back from frost.
Brugmansia are easily over wintered in an unheated garage or basement.
Colocasias are an easy bulb to over winter.
Ipomea batatas or sweet potato vines can be dug and stored or you may continue to grow them indoors.
Caladiums and Tuberous Begonias are both bulbs that can either be dug and stored or kept growing.
The last plant that is easy enough to grow from seed is Clitoria.
If you decide to over winter your plants in the house and they go dormant, either move them to a cooler area or be sure to give them a small amount of water each month so that the bulbs or rhizomes do not dry up and die.