One of the most difficult issues faced by commercial tomato growers is coping with soil borne diseases. Soil in which tomatoes are grown over several seasons without the benefit of crop rotation is more prone to carrying diseases that can adversely affect tomatoes. One way to raise a healthy crop of commercially desirable tomatoes such as heirloom varieties is to graft scion branches onto the roots of hardier hybrid root stock plants.
Choose plants for grafting that have the same size stem and are at least six inches in height.
Soak the root ball of your scion and root stock tomato plants in water for one hour before grafting.
Slice the top of the leader from the root stock plant just above the node (the point where a leaf emerges) with a scalpel. Cut the stem into a V shape by slicing cleanly downward from each side of the plant's stem. The tip of the V should meet in the middle of the stem. Each side of the V should slope at a 45 degree angle.
Slice the stem of the scion plant so that it comes to a point that would exactly fit into the V shaped cut of the root stock plant. Fit the two plants together along their cuts so that the outer layer of each stem meets along the cuts.
Place a silicone grafting clip around the tomato stem to hold the graft in place. The silicone grafting tip will help hold moisture into the union and will protect it while the plant heals.
Create a healing chamber by draping a piece of greenhouse plastic over the tomato plant like a tent. The greenhouse plastic will hold in heat and moisture while the tomato heals.
Drape a tarp over the greenhouse plastic. This will protect the tomato from the sun while it heals. Keep the tarp in place to keep the tomato plants in total darkness for two to five days. Replace the tarp with a sun shade once the scions of the plants appear to recover and seem less wilted.
Slowly decrease the humidity in the plastic tent by creating openings in the ends. Gradually remove the shade and the plastic after a few days to allow the plants to grow used to full sun and outdoor conditions.