Install a trellis for the Manettia cordifolia. It doesn't need a large support structure, but it does need something on which to climb.
Allow the soil to dry before watering. Water deeply, to a depth of 10 inches for the ground-grown M. cordifolia and until the water drains from the bottom of the pot for the container-grown plant.
Fertilize the vine with 1/2 tsp. of 7-9-5 fertilizer, diluted in a gallon of water. Apply the fertilizer every other week.
Prune the Manettia cordifolia, after it finishes blooming, to keep it to the size you desire. Don't be afraid to prune hard as it will recover quickly.
Cut the ground-grown plant back to the soil after the first freeze. Cover it with 3 inches of leaves or straw. Remove the mulch in the spring.