All tomatoes are either Bushes (determinate) or Vines (indeterminate). Determinate tomatoes stop growing on their own, and produce all of their fruit at once. Your heirloom tomatoes are vines, or "indeterminate". This means they will produce fruit all season. If left alone, they will grow into an unruly tangle of stems.
If you're short on space and if you want earlier and larger fruit, then prune
Types of Growth
The main vine. Everything else will come off it. It wants to split into many branches, but you won't let it.
Growing off at right angles, these little fellows break the vine up into sections. They get leaves and help with photosynthesis.
These grow in the middle of sections, coming directly off the vine. These flowers become fruit; we love them!
These grow out of the crotches of the right angle leaf stems. They must be removed; pinch them off with your fingers.
- For a well-behaved vine, prune to a single stem, or a y-shaped vine with a short mother stem and two long main stems. In areas with intense sun, such as the southwest, more leaves are welcome; a single stem can result in sun-scalded fruit. Make sure to pinch off dead leaves.
- Pruning is easy; snap out the suckers that grow out of the crotch made by the leaf stem joining the main stem. The best snapping-time is when suckers are 3 to 4 inches long.
- For a double stem, or Y-shaped vine, allow a sucker near the lowest flower cluster to grow.