How do I care for tomato plants in pots?

As time goes by the tomato plant starts loosing leaves and smaller branches as the tomato ages and it starts on the bottom. You could have one of the numerous viruses that tomatoes can get, but if it is a healthy older plant, it is most likely just getting old and loosing its "hair" just like men do as they age. I have that happen all the time and still get tomatoes until our first frost in the fall.

When a plant dies at the base it's usually from inconsistent watering. The plant needs water and consumes it thru the root system and upwards. If there is no moisture in the soil, the plant will start to die from the bottom up.

Perhaps try planting them upside down in a hanging planter. I used an old plastic coffee can. Drill a hole in the bottom big enough to put starter plant thru so just roots are inside, and 3 or 4 holes around rim for twine so you can hang from a shepherd hook, pack with soil, water well...enjoy!!!

I put packing popcorn in the bottom of my pots before adding soil. This allows the water to got to the bottom and then The roots can drink from the bottom. Cheaper than buying self watering pots.

they do loose leaves from bottom up but over watering will cause it too. let them dry completely before rewatering

Make sure the bottom of the pot has drainage holes,the plant will die from "wet feet"