Leggy seedlings are often a result of inadequate light. This can cause the plants to stretch toward the light source. To prevent leggy seedlings, ensure your seed starter tray is placed in a location with sufficiently bright yet indirect light. Alternatively, you can use artificial grow lights to provide enough light for proper development. If your seedlings are leggy despite being placed in a location with adequate light, it’s likely because they are growing too quickly. This means they likely require more nutrients than what they have access to in their growing medium. In this case, check to make sure that your seed starter tray has been watered sufficiently. Also, consider using a liquid fertilizer solution to give your seedlings an extra boost.