Peony is a woody shrub that is a popular choice for home landscaping because of its showy flowers and low-maintenance needs. Peony grows by rhizomes that spread beneath the soil, producing new shoots and buds for flowers. Peony requires five to eight hours of sun per day, and soil that drains well. Peony plants produce beautiful blooms of their distinct variety, but can develop color changes due to a number of factors.
The age of the plant affects the intensity of the color of blooms. Peonies may take up to two to three years to establish before the full beauty of the color of their blooms shows. After many years, the flower color may fade a bit as the plant becomes less efficient in producing blooms. This is especially true of hybrid varieties that may have multiple shadings on flowers when young, then fade out to a single color as the plant ages. Varieties of yellow and coral tend to fade to lighter shades as they age.
Peony shrubs do not change color in themselves. A red variety will always produce red peonies of some shade or another. New seedlings may appear to be of a different color than the parent bush, but this is usually due to a seedling of a different color shrub becoming intermixed with the seedlings of another, according to the website Peonies.
Cool and shady weather conditions can affect the color of peonies. White varieties may be less vividly white after a cold, dark spring, according to Paeonia Passion. Bi-colored varieties may intensify under these same conditions. Too much sunlight can also fade some colors of peonies. Though peonies generally like full sun conditions, excessive amounts of sunlight will fade the blooms, so providing a bit of shade for the plants will help to preserve the color. Irrigating plants that stand in full sunlight also helps to keep flower color.
Peonies are subject to a number of diseases that can discolor stems, leaves and flowers, including peony ringspot virus and botrytis blight. Carefully remove affected parts and destroy the plant debris. Then, dust the plant with a fungicide recommended by your local agricultural extension service. Virus infections may require removal of the entire plant. Do not replant peonies in that location for several years. To avoid contamination of the remainder of the peony plants, clean pruning and cutting tools with 70 percent rubbing alcohol solution or a 10 percent bleach solution, according to University of Minnesota horticulturists.