Answer: It's not unusual for the oldest leaves (those at the bottom of the plant) to turn yellow and die. The plant is simply putting more of its energy into producing new leaves. Check the bottoms of the pots; if roots are escaping from the drainage holes, you should repot. If not, they should be okay. Overwatering can cause yellowing leaves so be sure to water only when necessary and allow the soil to dry out slightly between watering. When you water, immerse the pots in a larger container of water and allow to sit for 5-10 minutes, then remove and allow to drain. Watering in this way will thoroughly moisten the soil, driving out any air pockets around the roots. You shouldn't have to water again until the top of the potting soil is dry. You might also feed with a half strength dilution of water soluable fertilizer every two weeks. Best wishes with your tomatoes!
Q&A Library Searching Tips