Answer: The bulbs may have multiplied and be in need of lifting and replanting. They may also benefit from an application of fertilizer in early fall as they begin to root and again in early spring just as they emerge from the soil. It is also important to allow the foliage to grow and mature and ripen for as long as possible before removing it. The leaves should be at least half way browned before you remove them as this is how the bulbs replenish themselves. Another thing to do is to remove the spent flowers to prevent the bulbs from using energy to set seed. They should be planted in full sun or at least half day sun for best performance. Finally, some varieties are just shorter lived than others and do not persist over time under garden conditions.
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