Regular tomatoes have a hard time in pots, but grape tomatoes do well if they have a cage to climb. They're the anti-gardening crop, thriving best on neglect. Got a dead potted plant? Chop it into its own soil with a spade, squish a baby tomato into it, pour some water over it, leave it in the sun and ignore it, except to pour water on if you're watering your other pots. Keep firmly in mind that you don't care if anything grows there, weeds or the old roots or the seeds or anything, you're just keeping the good bugs in there from dying out completely. That's the magic spell. In fact, they might not grow until you forget you planted them, then suddenly they'll appear.