Choose large, healthy carrots that still have greenery at the top, but do not use those that still have the full greens on the top. Cut off the top of each about one inch from the crown using a sharp knife. Trim any remaining greenery down very close to the top of the carrot.
Put a one-inch layer of sand or pebbles in a shallow bowl. Place each carrot top into the bowl, pushing the cut end of the carrot slightly into the sand or pebbles. Add more pebbles or sand to hold the carrots in place, leaving approximately one to two inches of the carrot exposed above the pebbles or sand. Space the carrots about two inches apart.
Fill the bowl with lukewarm water so the sand and pebbles are wet and the carrot is resting in the water.
Put the bowl with the carrot tops in a sunny place, such as a window sill. In a few days you will see lacy, green, fern-like sprouts emerging from the top of the carrot. The carrot will not grow roots.
Add water to the top of the pebbles or sand to keep the water topped up so the carrots do not dry out.