Yes, you can plant tomatillos and tomatoes together, but the practice requires careful management to ensure a successful harvest from both. Both vegetables belong to the nightshade family (Solanaceae), giving them similar growing needs and vulnerabilities to pests and diseases. However, they belong to different genera: the tomato is Solanum lycopersicum, and the tomatillo is typically Physalis philadelphica or Physalis ixocarpa. Strategic planting is necessary to minimize risks associated with their shared lineage.
Shared Needs and Resource Competition
Tomatoes and tomatillos require identical growing conditions, including full sun exposure for a minimum of six to eight hours daily. Both are heavy feeders that thrive in rich, well-drained soil abundant in organic matter. They also demand consistent, deep watering to support vigorous growth and fruit production.
Placing these species too close together leads to intense root competition for finite resources. The dense, rapid growth of the tomatillo can quickly shade and out-compete a developing tomato plant, reducing the tomato’s yield and fruit quality. To prevent this resource strain, physical separation is necessary to allow both plants adequate access to nutrients and water without aggressive root entanglement.
Managing Shared Pests and Diseases in Close Quarters
The shared family membership means both species are susceptible to the same pathogens and insect pests. Fungal diseases like Early Blight and Septoria Leaf Spot can easily spread between tomato and tomatillo foliage in humid conditions. Soil-borne fungi such as Fusarium oxysporum (Fusarium wilt) can also infect both genera through the root system.
Crowding the plants together creates a humid, low-airflow environment that accelerates the spread of fungal spores. Both plants are targeted by common Solanaceae pests, including whiteflies and aphids, which feed on sap and transmit viral diseases. The potential for a localized disease or pest outbreak to wipe out both crops simultaneously is the primary biological risk of planting them in close proximity.
Mitigation requires cultural practices focused on maximizing air circulation. Utilizing drip irrigation or watering at the soil level keeps the foliage dry, which discourages fungal spore germination. Proper pruning to remove lower leaves and dense interior growth promotes airflow. Immediate removal and destruction of any plant showing signs of significant infection is necessary to protect the neighboring crop.
Cross-Pollination Concerns and Genetic Safety
A common concern is the possibility of cross-pollination resulting in a hybrid fruit with an undesirable flavor. This concern is unfounded for the current harvest due to the significant genetic barrier between the two plants. Tomatoes (Solanum) and tomatillos (Physalis) belong to different genera, making natural hybridization biologically impossible.
A flower on a tomato plant pollinated by a tomatillo will still produce a normal tomato fruit, and vice versa. The fruit’s characteristics for the current year are determined by the parent plant’s genetics, not the pollen source. The current crop’s quality, taste, and texture will remain true to the plant from which it grew.
The only potential genetic risk is for gardeners who save seeds for the following year. While the seeds saved from a tomato plant are safe, tomatillos can cross-pollinate with other closely related Physalis species, such as ground cherries or wild relatives. For the home gardener not intentionally breeding, the fruit produced for consumption is safe and unaffected by the nearby presence of the other species.
Best Practices for Companion Planting
Incorporating a physical buffer to limit disease and competition is highly recommended when co-planting. A separation distance of at least five to ten feet reduces the likelihood of root competition and prevents the easy transfer of airborne disease spores. Planting them in separate raised beds or containers is an excellent way to maintain a clean barrier between the root systems.
Using buffer plants can further aid in pest management by interrupting the pathway between the two main crops. Companion plants like basil or marigolds, known for their pest-repellent properties, can be strategically placed between the tomato and tomatillo rows. Providing robust physical support, such as sturdy cages or stakes, is also beneficial, especially for the sprawling tomatillo, which prevents its foliage from smothering nearby tomato plants and keeps leaves off the soil.