Answer: You're correct in the fact that the leaves supply nutrients to the bulbs for the following year's display, so it is important to allow them to wither and die on their own. There are concerns about tying the leaves together for the sake of neatness. If you tie too tightly, you can stop the flow of nutrients to the roots, which completely defeats the purpose of allowing the leaves to die back on their own. However, if you wait until most of the green has drained from the leaves and they're a yellowish-tan, you can gather them together and lay them down on the soil surface so they're not as visible. This still allows for the last little drops of carbohydrates to be transported to, and stored in the bulbs.
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