The Tomaco plant offers gardeners the unique opportunity to harvest two distinct crops from a single plant. This space-saving innovation produces tomatoes above the ground while simultaneously yielding potatoes beneath the soil. Achieving this dual-cropping success relies on a skilled botanical technique that physically joins two compatible plants. This process bypasses traditional breeding methods to create a single, highly productive plant structure, appealing to both home growers and commercial producers.
Defining the Tomaco Plant
The Tomaco plant is not a genetic hybrid created by cross-pollination or genetic modification, but rather a graft. This technique involves physically joining the stem of one plant to the root system of another, allowing them to grow as a unified organism. The top part, which produces the tomatoes, is known as the scion, while the potato root system, which remains below ground, is called the rootstock.
The viability of this pairing stems from the fact that both the tomato (Solanum lycopersicum) and the potato (Solanum tuberosum) belong to the same plant family, Solanaceae, commonly known as the nightshade family. This close botanical relationship ensures the necessary physiological compatibility for the vascular systems to fuse and exchange water and nutrients. Commercial versions of this plant have been marketed under names such as ‘TomTato’ or ‘DoubleUP Potato Tom’. The graft union allows the tomato foliage to produce energy through photosynthesis, which is then transported down to the potato roots to fuel tuber development.
Essential Materials and Timing
Successful Tomaco creation begins with careful selection of the scion and rootstock. They must have stems of nearly identical diameter to maximize the contact area between their cambium layers. The tomato scion should be a healthy cutting, approximately four to six inches long, taken from the actively growing tip of a preferred tomato variety. The potato rootstock should be a vigorous, established plant, grown from a single seed potato until its stem is sufficiently thick.
The procedure requires specialized tools, including a sharp utility knife or razor blade, to ensure clean, precise cuts that promote rapid healing. Sterilization of the cutting tool is necessary and can be achieved using rubbing alcohol or a dilute bleach solution to prevent the transmission of pathogens. Grafting clips, made of silicone or plastic tubing, or specialized grafting tape are used to hold the delicate union firmly in place during the healing period.
Optimal timing for the procedure is late spring or early summer, when both plants are in a period of active, vigorous growth. This timing coincides with the highest concentration of hormones and metabolic activity, which is conducive to the rapid formation of callus tissue necessary for the graft to heal. The plants must be well-hydrated before the procedure to reduce stress and wilting.
Step-by-Step Grafting Technique
The most common method for joining these plants is the cleft graft, which is well-suited for herbaceous stems of similar size. First, the potato rootstock is prepared by cutting the main stem horizontally, approximately four to six inches above the soil line. A clean, two-inch deep vertical slit is then carefully made down the center of the remaining potato stem to securely hold the tomato scion.
Next, the tomato scion is prepared by making two opposing diagonal cuts at its base, forming a sharp, elongated wedge shape. This wedge must be precisely cut to match the length of the slit in the potato rootstock. This cut exposes the cambium, the thin layer of actively dividing cells responsible for forming the healing union.
The wedged tomato scion is then gently inserted into the vertical slit on the potato rootstock. Ensure that the cambium layers of both plants are perfectly aligned on at least one side. Alignment is the most important factor for the graft to take, as it enables the vascular tissues to reconnect. Once aligned, the union is secured tightly with a grafting clip or tape to prevent movement and maintain consistent pressure. The finished graft should immediately be placed in a humid, shaded environment to prevent the scion from drying out before the vascular connection is established.
Post-Graft Care and Harvesting
Immediately following the grafting procedure, the newly joined plant requires a sheltered environment with very high humidity. This is often achieved by covering it with a clear plastic bag supported by stakes. This “healing chamber” minimizes water loss through transpiration until the graft union has fully healed, which typically takes between seven and fourteen days. The plant should be gradually acclimated to normal growing conditions by progressively opening the bag over a few days once new growth is visible.
A persistent management requirement is the removal of any vegetative growth that appears below the graft union on the potato rootstock. These unwanted shoots, known as suckers, draw energy away from the scion and compete directly with the developing potato tubers, negatively impacting both harvests. Any potato-like foliage emerging from the rootstock must also be immediately removed to ensure all energy is directed to the tomato scion and the underground tubers.
The harvesting schedule is staggered, reflecting the natural maturation times of the two crops. The tomatoes on the scion will ripen first, generally after approximately twelve weeks, and can be picked throughout the summer months. The potato tubers below ground are ready for harvest much later, typically in early autumn. This occurs once the tomato foliage on the scion begins to yellow and die back naturally, indicating that the plant has finished its seasonal growth and stored energy in the potatoes.