A favorite of gardeners, and often grown in old-fashion gardens, stock plants produce colorful stalks of spicy fragrant flowers. In U.S. Department of Agriculture hardiness zones 7 to 10, stock plants are considered tender perennials and may be winter hardy. Grown in colder zones, your stock plant should be thought as an annual. Although the flower stalks of stock plants are long lasting, after seven to 10 days the flowers will begin to die and fall off. Trimming off the dying flower stalks will keep the plant producing new flowering stalks throughout the summer.
Wait until the flowers on your stock plant begin to wilt and die. The flowers are on a single stalk and will begin to die from the bottom up. As they die completely, the flowers will naturally drop off.
Trim the flower stalk from the stock plant with sharp hand pruners or snips.
Cut the stalk as close to the base of the stock plant as possible. This directs the energy of the plant to producing a new flowering stalk instead of trying to maintain the dying flower stalk.