Grafting vegetables--including tomatoes, cucumbers and eggplants--offers growers with greenhouses a way to combine the best features of two different strains. A tomato variety with excellent disease resistance but marginal fruit quality could serve as rootstock for a tomato type with better fruit quality but less vigor. The grafted plant exhibits the best qualities of both.
Grafting hothouse plants requires special equipment both for the grafting process and the healing period that follows. Cleft grafting works with larger plants with stems from 1/8 to 1/4 inches across and is generally the easiest method to learn.
Plant rootstock seeds in peat pots five days before planting an equal number of seeds chosen for scion or fruiting stock. Nurture the plants in the greenhouse until both rootstock and scion plants grow four to five leaves.
Move the plants to a shaded area of the greenhouse for the actual grafting to reduce heat stress on the plants. Use the razor blade to cut the scion plant straight across through the stem above either the second or third leaf. Match the diameter of the cut end of the scion to a location on the rootstock stem which also will leave two or three leaves on the rootstock plant. Cut the rootstock straight across and discard the rootstock's top.
With the razor blade, split the top of the rootstock stem 5/8 inch deep. Trim two sides of the base of the scion to a wedge shape 5/8 inch long. Insert the wedge carefully into the cleft of the stem.
Use a grafting clip designed for stem diameters of 1/8 to 1/4 inch to hold the graft in place. The spring-loaded plastic jaws provide reinforcement and protection against drying and should remain on the plant for a week to 10 days until the wound fully heals.
Cover grafted plants with a humidity tent of plastic or newspaper laid over a wire frame. Mist the plants with water twice a day for three to five days after grafting. A constant temperature of 86 degrees F and relative humidity of 95 percent provide best conditions for healing.
Expose the plants gradually to normal greenhouse conditions. Open the humidity tent for a few hours in the morning and evening and increase the exposure time daily. Mist as necessary to prevent plants from wilting. Plants transition to the greenhouse fully in seven or eight days after the grafting operation.