The answer to planting two tomato plants together is yes, though this practice requires careful management due to significant trade-offs. Gardeners often use this method to maximize yield in limited spaces, such as containers or small raised beds. Planting two heavy-feeding plants in the same spot deviates from standard cultivation practices and demands specialized care. Without adjusting your approach, the plants will compete for resources, leading to stunted growth and reduced fruit production.
Understanding the Double Planting Technique
The technique involves planting two tomato seedlings very close together, using the space typically allocated for one plant. Instead of the standard 18 to 24 inches of separation, the two plants are placed roughly 4 to 6 inches apart, often sharing a single planting hole. This close proximity allows the pair to be supported by one shared cage or trellis, saving both material and garden space.
While this method works for any variety, it is easier to manage with determinate tomatoes, which grow to a set height and ripen fruit within a short window. Indeterminate varieties, which vine continuously and grow much larger, are more challenging because their aggressive growth exacerbates resource competition. The primary motivation for this intensive planting is vertical space efficiency.
The Challenge of Resource Competition
Planting two tomatoes in close quarters immediately creates intense competition for three major resources: nutrients, water, and light. Tomatoes are “heavy feeders,” quickly depleting the soil’s reserves, particularly nitrogen and phosphorus, which are necessary for strong foliage and root development. With a doubled root mass in the same volume of soil, this depletion occurs at an accelerated rate, often leading to nutrient deficiencies and smaller, less vigorous plants.
Competition for water is equally significant, as the combined foliage transpires twice the moisture, causing the soil to dry out rapidly. Inconsistent soil moisture, a direct result of this high demand, stresses the plants and often results in physiological disorders like blossom end rot. This condition is caused by the plant’s inability to draw up enough calcium when water delivery is erratic.
The dense canopy created by two closely planted tomatoes reduces light penetration to the lower leaves. Shaded leaves perform less photosynthesis, which reduces the plant’s energy production and fruit-setting capacity. The lack of air movement through the packed foliage also raises humidity, creating an ideal microclimate for the spread of fungal diseases, such as early or late blight.
Adjusting Care for Closely Planted Tomatoes
To mitigate resource competition, the care regimen for double-planted tomatoes must be intensified. Since the plants are heavy feeders, a consistent fertilization schedule is mandatory to replace exhausted soil nutrients. After the initial growth phase, focus on fertilizers with higher ratios of potassium and phosphorus to support flowering and fruiting, rather than excessive foliage growth.
Aggressive pruning is required to maintain plant health and productivity. It is necessary to remove suckers—the small shoots that develop in the leaf axils—to limit foliage and encourage a single or double main stem per plant. This pruning improves air circulation, reduces the risk of fungal diseases, and allows light to penetrate the canopy, promoting fruit development.
Given the combined weight of two plants, a strong, permanent support system, like a sturdy cage or trellis, must be established at planting. The increased water demand necessitates consistently deep watering to keep the soil evenly moist. This moisture management is crucial for nutrient uptake and preventing common issues like blossom end rot.