Determinate tomato plants grow into bushes of a fixed size. These plants produce most of their fruit all at once and have a short window for harvesting, usually about two weeks.

Indeterminate tomatoes grow into vines and need more support. These tomatoes have fruit that sets throughout the growing season. Vining tomatoes need more pruning and maintenance throughout the season because the vines will continuously grow and can reach heights of 6-8 feet.

Yes, indeterminate tomatoes, such as brandywine black, benefit from pruning.
Indeterminate plants will grow unless stopped by external factors. Pruning these plants regularly allows their energy to be focused towards producing larger, healthier fruit.

Yes, tomatoes need trellising or a tomato cage to grow and keep their fruit off the ground. This allows for better airflow for the plant and helps prevent diseases. Fruit that is touching the ground will become misshapen, rot faster and is more susceptible to pests. It also can help with weed control, watering, and fertilizing.
Because of their height and weight, indeterminate varieties may need larger, sturdier cages.

Select a fully ripe tomato. Scoop the seeds and surrounding pulp into a container, add water, and allow it to ferment for a few days. Seeds that will be viable for planting will sink to the bottom. Skim off the floaters and gel on the top of the water. Then, rinse the remaining seeds thoroughly, removing all pulp and debris. Allow the seeds to dry completely before storing.