The germination time for lychee trees after transplanting can vary significantly depending on several factors such as soil conditions, climate, and the health of the seedlings. On average, lychee seeds typically germinate within 7 to 14 days after being planted. However, this period can be extended to 21 days or more in less favorable conditions. Research conducted by the Agricultural Research Service of the United States Department of Agriculture (USDA) indicates that optimal germination rates are achieved when the soil temperature is between 70°F and 90°F (21°C to 32°C), and when the seeds are kept moist but not waterlogged. The germination rate can also be influenced by the initial health of the seedlings, with healthier seedlings generally exhibiting faster germination times. For instance, a study published in the Journal of the American Society for Horticultural Science found that seedlings with a higher initial vigor had a significantly shorter germination period compared to those with lower vigor. This highlights the importance of selecting healthy seedlings and providing them with an appropriate environment to ensure successful germination after transplanting.