Growing pineapples can be very rewarding in your greenhouse. Though it takes 18 to 24 months, the taste of the fresh fruit is out of this world. Harvesting a pineapple can be a little tricky. When harvesting make sure your pineapple has a good amount of a light yellowish color on it. Usually ¼th to 1/3 is good. This will allow it to ripen off the plant if stored in a cool place but do not refrigerate. When ready to eat the pineapple should have a fresh aroma and be almost completely yellowish in color. Another way to harvest the pineapple is preferred by many people is to cut it totally green from the plant and allow it to ripen in the same manor. However with this method you have to know when your pineapple is fully mature and if you keep a record of the amount of months you grew it that 18 to 24 month period will work. A pineapple producing it second or third fruit will take a little less time if your plant is kept healthy. Remember when cutting your pineapple from the plant use a clean sharp knife and make an even cut being careful not harm the plant or other fruit close to it that maybe be starting to grow.