Oh, and there's this: Fertilizing Citrus Indoors Meyer lemon trees are heavy feeders, especially during their active growing season (spring and summer). Use a fertilizer designed for acid-loving or citrus plants, following the label instructions carefully. Recommended options include: E.B. Stone Citrus & Fruit Tree Food – balanced nutrients for flowering and fruiting. Down to Earth Citrus Mix Fertilizer – organic and slow-release. Phyta-Grow Leafy Green Special Fertilizer – supports foliage and overall plant health. Maybe it's been hungry. It might not enjoy the same food as pot does.