The best you can do is put the flower stem in water and enjoy it. Cut orchid flowers last a long time in water and will last even longer if you change the water regularly and add floral preservative each time. You can purchase packets of floral preservative at any florist. It is especially helpful in encouraging all of the buds to open. Once the last flower fades from your orchid stem, toss the whole works. A new orchid won't grow from a flower stalk.