The question of whether to mix different tomato varieties is common for home gardeners seeking diverse harvests, from small cherry tomatoes to large beefsteaks. The straightforward answer is that you can successfully plant various types—including heirloom, hybrid, determinate, and indeterminate—in close proximity within your garden. While all tomatoes belong to the same species, Solanum lycopersicum, successful mixed planting requires careful consideration of their distinct growth patterns and how their proximity can affect garden health.
Compatibility of Different Tomato Varieties
All cultivated tomatoes share fundamental biological needs, including warm soil, consistent water, and at least six to eight hours of direct sunlight daily. This shared need means varieties can be grown in the same bed without competing for basic nutrients in a way that is detrimental to either plant. The real challenge in mixed planting comes from managing the difference in their physical size and growth habits.
The two main growth types are determinate and indeterminate varieties. Determinate tomatoes, often called “bush” varieties, grow to a predetermined height, usually three to five feet, and produce the majority of their fruit within a short, concentrated period. Indeterminate varieties are vining plants that continue to grow, flower, and produce fruit until the first frost, sometimes reaching heights of 10 to 12 feet.
Planting these two types too closely creates physical incompatibility. The continuously growing, tall indeterminate varieties can easily shade out the shorter determinate plants, severely limiting their access to sunlight. This shading reduces the determinate plants’ ability to photosynthesize effectively, leading to lower yields. Successful mixed planting depends on physically accommodating these contrasting growth patterns to ensure all plants receive adequate light and air circulation.
Understanding Cross-Pollination and Seed Integrity
A common concern is whether planting different varieties together will result in strange-looking or poor-tasting fruit that same season. Tomatoes are primarily self-pollinating; each flower contains both male and female parts and typically pollinates itself before the flower fully opens. This means the fruit you harvest in the current season will always be genetically true to the plant it grew on.
Cross-pollination is a relatively rare event in tomatoes, though it can occur when insects like bumblebees facilitate the transfer of pollen between different varieties. When cross-pollination happens, the resulting fruit remains unchanged, but the seeds inside that fruit carry the new, hybrid genetics. If you save seeds from a cross-pollinated fruit and plant them the following year, the resulting plant will grow an unpredictable mix of the two parent varieties.
This genetic consideration is only relevant for gardeners who save seeds, particularly those growing heirloom varieties who want to ensure their seeds remain genetically pure. For those who purchase new seeds or seedlings each year, cross-pollination is not a factor that should influence decisions on mixed planting for the current harvest. The fruit’s quality and characteristics are determined by the parent plant, not the pollen source.
Optimizing Layout for Mixed Planting
Arranging different tomato types thoughtfully is necessary to prevent the taller varieties from hindering the growth of the shorter ones. Position the tallest plants where they will not cast shade onto their neighbors as the sun moves across the sky. This typically means placing the vining, indeterminate varieties on the north side of the garden or planting bed.
Proper spacing is necessary for both light penetration and air circulation. Determinate varieties, which are bushier and more compact, can often be planted as close as 18 to 24 inches apart within a row. Indeterminate varieties, which demand more space to manage their continuous growth, should be spaced more generously, ideally three to four feet apart, to allow for their extensive support systems. All varieties benefit from support, but indeterminate plants require tall stakes, cages, or trellises, which should be factored into the overall layout.
Training the indeterminate plants vertically on these supports helps to maximize light exposure for the entire garden plot. Adequate space between plants also allows gardeners to move freely for maintenance tasks like pruning and harvesting. Using a north-south orientation for rows, where feasible, ensures that both sides of the plants receive relatively even sunlight throughout the day.
Disease and Pest Management in Diverse Gardens
When different tomato varieties are planted close together, the density of the foliage increases the potential for rapid disease and pest spread. Many common tomato pathogens, such as early blight, late blight, and fusarium wilt, thrive in humid environments. Closely spaced plants create a dense canopy that traps moisture and limits airflow, which encourages fungal and bacterial diseases.
To mitigate this risk in a mixed garden, focus on practices that increase ventilation and reduce moisture on the leaves. Watering plants at the base, rather than using overhead sprinklers, helps keep the foliage dry. Selecting varieties that have resistance to common local diseases is a strong preventative measure, often indicated by letters like V, F, or N on the plant tag, which stand for resistance to Verticillium, Fusarium, or Nematodes. Practicing crop rotation, where tomatoes and related plants are not planted in the same spot for three to four years, also helps break the cycle of soil-borne pathogens.