The yellowing of the edges of the older leaves is likely due to a potassium deficiency, especially as the tomato plant is about to enter its fruiting stage when the demand for potassium increases.
Recommended fertilization method during the fruiting period:
- Alternate weekly between applying Mr Ganick 532 Organic Leafy Fertilizer and Mr Ganick 426 Organic Fruit & Vegetable Fertilizer. Each time you fertilize, use one handful of fertilizer and spread it evenly around the root zone.
- Ensure the plant gets plenty of sunlight, as adequate sunlight aids in photosynthesis, promoting growth and fruit development. Ensure the plant receives at least 6-8 hours of sunlight daily.

