One of the classifications you will often see on the label of a tomato plant or on a packet of tomato seeds is "determinate" or "indeterminate." These terms refer to the growth habit of the tomato plants. They essentially mean bush or vining, respectively.
All tomato plants are vines that would sprawl along the ground if gardeners did not stake them to grow upward. If left to their natural tendencies, tomato vines would become a damp, tangled mess on the soil, where they would attract diseases and pests. And the indeterminate varieties tend to grow much longer than the determinate varieties.
Determinate tomatoes are varieties that grow to a fixed mature size and ripen all their fruit in a short period (usually about two weeks). Once this first flush of fruit has ripened, the plant will begin to diminish in vigor and will set little to no new fruit.
Determinate tomato varieties are often referred to as “bush” tomatoes because they do not continue extending in length throughout the growing season. They are generally smaller plants than indeterminate tomatoes, with most growing to a compact 4 to 5 feet tall. Pruning and removing suckers from determinate tomatoes is generally not needed because they stop growing on their own.
Despite their compact size, staking or caging is still recommended. They will be supporting a heavy load once all of the fruits set and begin to plump up and ripen. This can put considerable weight on the branches, so staking will help the plant.
Growing determinate tomatoes is practical when you want a lot of tomatoes at once, for making juice, sauces, and canning. Many paste or Roma tomatoes are determinate varieties, such as 'San Marzano' and 'Amish Paste'. Some others have been bred to be determinate, so they can be harvested in quantity all at one time. These include 'Celebrity', 'Marglobe', and 'Rutgers'.
Unlike determinate tomatoes that hit their mature height and set all their fruit at once, indeterminate tomato varieties are vining plants that continue to extend in length throughout the growing season. This is why you will sometimes see them referred to as "vining" tomatoes.
Indeterminate tomato varieties also continue to set and ripen fruit throughout the growing season until frost kills the plants. They will give you a slow and steady supply of tomatoes, rather than one large harvest. However, they tend to start ripening a little later in the season than determinate varieties do because they first spend a good amount of time growing tall. It is a good idea to pinch back some of the suckers on indeterminate tomatoes to prevent unmanageable growth. Never pinch out a sucker directly below a blossom as this causes uneven growth in the plant and will reduce your harvest.
The majority of tomato varieties are indeterminate, including most heirlooms and cherry types. Even many dwarf tomato varieties are indeterminate. Some of the most popular tomatoes to grow, including 'Beefsteak', 'Big Boy', 'Brandywine', 'Sungold', and 'Sweet Million', are indeterminate varieties.
Early producing varieties, such as 'Early Girl', are also indeterminate. However, because they tend to mature earlier and die back before the end of the growing season, they are sometimes labeled semi-determinate.
The indeterminate varieties need large, sturdy stakes or caging for support because of how long they grow. The plants can reach 6 to 10 feet (or taller) and become very heavy.
Alternatively, tomato plants can be grown upside down as a hanging vine. This eliminates the need for support, keeps the fruit up off the ground, and permits the plant to grow in an open manner to allow sunlight to reach all its parts. However, the plant still will be heavy, so use a strong hook and sturdy hanger.
Both determinate and indeterminate tomato varieties have their pluses and minuses. It really depends on how you plan to use the tomatoes and the length of your growing season. If you want a thick tomato for making sauces, you are better off with a paste tomato, which tends to be determinate with fewer seeds and more meat. If you typically eat your tomatoes fresh and want a season-long supply, go for an indeterminate variety.
Moreover, if you live where the growing season is only a couple of months long, determinate tomatoes might be the better growing choice for you. However, there are short season indeterminate varieties, such as the early maturing tomatoes, that would probably ripen for you. Experiment to see which varieties grow best in your area, as well as which you enjoy eating the most.