Lily of the Valley Turns Brown Every Year

I have a number of lilies of the valley planted in a shaded area on the northwest corner of my house. Every year in late summer and fall, the lilies begin to turn brown and wither. They seem to resurrect and bloom once again the following spring. How can I keep the lilies from turning brown so early in the fall season?

Leaf spot and stem rot can cause the symptoms you describe. Though infested plants look bad, as you discovered, they usually survive and return the following season. Remove and destroy infected leaves and stems as they appear. Remove all the foliage in fall to reduce the source of infection the following year. Dig and divide crowded plantings to increase air flow and light penetration and further reduce the risk of disease. Amend poorly drained soil before replanting. Dig several inches of organic matter such as compost, peat moss or aged manure into the top 6 to 8 inches of soil.