Lily of the Valley in bloom.
image by TopJabot:commons.wikimedia.org
Lily of the valley are flowering perennial herbs that sprout from underground rhizomes called pips. They bloom in the spring and early summer in crisp white or a very pale pink bloom. They thrive in partial shade to complete shade on the edges of woodlands, and naturalize rapidly to create dense carpets of smooth, green upright leaves. Lily of the valley are low maintenance and can simply be mulched over with compost in the late fall in preparation for next spring's bloom.
Plant lily of the valley pips where they will receive partial sun, dappled sun or complete daily shade. In warmer or drier climates full shade is preferable. Lily of the valley are relatively shallow-rooted, and will thrive as under-plantings for large shrubs and trees.
Provide a nutrient-rich soil that will hold moisture to the rhizome's roots but will still drain if drenched with rainfall or accidentally over-watered. Nearly all gardens, pastures or woodland soils are fine but heavy clay soil may be problematic for drainage reasons.
Water lily of the valley so that the soil is evenly and consistently moist but not sopping wet. Adjust irrigation as needed to compensate for rainfall. Apply a high-nitrogen, general purpose garden fertilizer in the spring and again in the fall to replenish the rhizomes while they prepare during winter for the following spring's bloom.
Mulch over the yellowing and wilting lily of the valley foliage in the fall before the first hard frost. Lay down an even 1-inch thick blanket of either compost, well rotted manure or leaf mold or some combination of the three to cover the plants. Apply the mulch after the second application of fertilizer.
Dig and divide the lily rhizomes when the plants become over crowded and are no longer performing well. Pull the rhizomes up in the fall or spring and cut or pull apart each rhizome into single pips with one bud each. Replant each individual pip so that the eye is facing up one inch beneath the surface of the soil and place at intervals of 4-inches apart.