Cut off the pineapple top (crown) using a sharp knife. Remove any extra leaves that may be near the bottom of the cut, and ensure that the cut is a clean one. Ideally, there should be no extra fruit left, as this can cause rotting.
Fill a small container with water and place your pineapple top in the water, cut side down. Be sure that the water does not touch the leaves. Check the water every 2-3 days and replace as needed.
Your pineapple plant will grow faster if placed in a sunny, south facing window. Depending on the temperature, amount of sunlight, and humidity, the pineapple will start forming roots within 1-3 weeks. Once that happens, you may transplant the pineapple in soil!
Remove the rooted pineapple from water and transplant into a large pot or container that's filled with moisture retaining soil. If you live in a tropical or subtropical climate, you may plant the pineapple directly outdoors. Add soil around the roots, making sure they're completely submerged in soil and tamp down with your hands.