My cilantro are about three inches tall and has been growing for about three weeks. Today, the leaves are wilting? This is on several of the plants, and some of the leaves’ edges are beginning to brown. Is this because of overwatering or overheating?
Most plants form a pair of cotyledons or "seed leaves" upon germinating, which don't look like the other, subsequent leaves. These only serve to get growth started, and you should expect them to wither away once the plant's true leaves get established.