The grocery store offers many more houseplants than you might imagine. Look beyond flowerpots of African violets, jade plants and spider plants. Look to the food itself.
Steer your grocery cart over to the produce section. Here is where you will find foods that will sprout roots and shoots, usually with no more coaxing than that of a little warmth and water.
Besides making houseplants, such "produce aisle" gardens are good for reminding children of the variety of plants that provide food. Also, these gardens give an appreciation for the fact that such foods as carrots, onions and potatoes are living foods, and as such, a valuable part of our diet. (Try planting a potato chip.)
Look first for foods that are fleshy storage roots--carrots, for example. Lop off and save a half-inch of the tops of the roots before you eat the rest of each carrot. Set the tops, bottom ends down, in a shallow pan of water or press them into moist soil in a flowerpot (perhaps to dress up the base of a lanky houseplant).
In a few days, the tops will sprout and then grow to become small jungles of ferny foliage.
If you bought carrots with their leafy tops attached, cut the leaves off before planting, or they will wilt. New tops will grow.
Another storage root worth planting is the onion. Watch what happens when you plant it. Either bury the bulb to half its depth in potting soil, or perch it with three toothpicks in a glass of water, with the bottom of the bulb just below the water line. A thick, green stalk, capped by a starburst of little white flowers will rise from the center of the bulb.
If it is spring by the time these carrot and onion "houseplants" have overstayed their welcome, discard them. Don't plant them in the garden, expecting to harvest them for the table. These plants are biennials, which grew their edible roots last summer.
This summer they will "eat" their roots for energy to produce seeds, then the plants will die.
The vegetable that makes a nice houseplant that you could plant out in the garden in spring is the sweet potato.
If you plant the fat root in either moist soil or water (again, perched with toothpicks), a twining vine will emerge. This plant likes warmth, and if kept happy, will send out many feet of purplish-green stems with smooth, dark-green leaves.
Don't try to gather together the whole vine when it's time to plant it outside. Just cut the vine into six-inch pieces, strip the bottom leaves from each piece, and plant the pieces indoors in potting soil. Within a month, each piece will be well-rooted and ready for transplanting to the garden.