One of the most exciting seasons for the vegetable gardener is the time when plants begin to grow noticeably larger day by day, predicting crops of garden-fresh vegetables to come. Plant growth involves complex biological processes, occurring out-of-sight in each cell. When growing tomatoes, understanding something about their growth habits helps you to make the best choices for your garden.
The growth of a tomato plant stem begins shortly after germination of the seed. As explained by the Washington State University Extension, germination begins when the root emerges and anchors the plant in the soil. Next, the stem emerges with two primitive leaves and begins to stretch for the surface and sunlight. Highly active areas of plant growth at the tip of the shoot let the plant grow quickly.
Apical meristem--the rapidly growing tissue found at the tips of plant stems--multiplies through a process called mitosis, in which cells duplicate their contents and then divide into two. This process causes the primary tomato stalk to elongate quickly. In addition, the apical meristem periodically differentiates into different types of tissue--producing leaves, flowers and other branches.
As a tomato grower, stem growth has particular implications when you select the best type of tomato for your garden. There are two types of tomatoes available, distinguished by the growth of their stems: determinate and indeterminate. Determinate varieties produce a flower, which in turn produces a tomato, at the end of each stem. Because flowers do not contain apical meristem, the plant stops growing at this point. Indeterminate varieties develop flowers alongside the stems, allowing the tip of the stem to grow indefinitely into vines.
The type of growth that's best for your garden depends on your needs. Determinate plants remain smaller and more compact than indeterminate, produce earlier tomatoes and do not require staking or caging. However, they produce tomatoes only for a limited time each season, and there may be some difference in taste, according to the University of Illinois Extension. Indeterminate varieties produce tomatoes later but continue producing through the entire season. Because they continue growing through the entire season as well, they require extra care, including staking, caging and pruning, to manage their growth.
The rapid growth of indeterminate tomatoes present challenges to the gardener. Vines snake along the ground, where fruit becomes susceptible to rot, and rapidly growing plants may put their energy into new stem growth rather than fruit development. Caging tomato plants keeps fruit off of the ground. Some gardeners prune their caged tomatoes back to three or four main stems so that plants put their energy into fruit set rather than stem growth.