Question
I live in Texas in the United States and my question is what is the proper way to root a sweet potato in water?I have been searching and one thing says to put the glass of water in a dark cool place, and then another says but it in bright light but not direct sunlight. Help please? Also I have my water just so that it is touching the tip of the bottom,is that enough water or too much? Thanks in advance.Sorry I forgot to mention they are store bought sweet potatoes that I bought for Christmas and didnt use.

Answer
i copied and pasted this article from canadien gardening magazine.
it explains most of what you want to know.  for propagation lighting i always recommend an easten exposure where the plant will get morning sun only.  this prevents the plant from getting too hot, which can kill tender new growth.  allow the bottom of the tuber to keep in touch w/the water surface in the container.
  
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by: Tina Forrester  
Sweet Potato Vine
Amaze the kids by sprouting a lush vine from this grocery-cart staple  
by Tina Forrester
Growing a lovely houseplant from a common sweet potato straight from the grocery cart is just as much fun for kids today as it was in Grandma's time. If you help your children sprout one, you can share in their delight as purplish-green leaves emerge from the top of a vegetable you usually boil and mash, or candy in butter and brown sugar. And, if you're lucky, your child's plant may produce some lilac-coloured blossoms.

The stubby vegetable is actually the storage root of Ipomea batatas  - the botanical name for the white or yellow sweet potato and the orange yam. Sweet potatoes are tropical American members of the morning glory family. Outside, they grow best where summers are fairly long and warm. Inside, they were once common houseplants grown on kitchen windowsills, the beautiful vines trained up and around window frames.

To help your kids grow their own vine, choose a firm sweet potato. Some are treated with heat to keep them from sprouting on grocery-store shelves, but most grow roots in a matter of days after being placed in water. Using four toothpicks, have your child suspend the vegetable on the rim of a jar or mug filled with water. Make sure the bottom half - the pointed end - is under water. Place in a sunny spot, and change or add water as needed. In a few days, roots will form below the water. And, two to three weeks later, leaves and stems will sprout from the top. Continue to grow the plant in water or, after a month or two, pot the sweet potato in a houseplant potting mix. Keep the soil moist. The stems are weak, so help your child tie them to strings, wire or a stake. Feed once a month with a balanced water-soluble fertilizer such as 20-20-20. As the vine grows, cut it back a few inches to force the plant to grow bushy.
good luck
rick in southern NJ
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