Answer: Greek Oregano is a heat and sun loving plant, even more so than basil, which can make it difficult to grow healthy seedlings at home. Based on your description I suspect the seedlings needed more light than they received. Other possible causes are that they were too crowded and/or over fertilized and/or overwatered and/or needed better air circulation, but the primary suspect is lack of light. If you are using a windowsill, you might consider supplemental light such as that provided by fluorescent bulbs.
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