Kumquats are the smallest members of the citrus family and the only citrus that has a sweet skin. The proper way to eat a kumquat is to bite into it like you would an apple and enjoy its sweet skin and sour fruit and juice. Like other citrus, kumquat trees have a limited life for effective production, which can be beneficially lengthened by grafting young stems, called bud sticks, to the old established tree's branches.
Select the bud sticks that will be used. Optimal bud sticks are roughly 1 year old and a quarter inch or less in diameter. If grafting cannot be done immediately, the bud sticks can be wrapped in wet paper towels and stored in the refrigerator for up to three weeks.
Determine the location for grafting. The best branches to use are those that are a half to three-quarter inch in diameter. Avoid placing the new bud stick in an area that will receive south or west sun exposure because it can become sunburned. Verify that the tree's bark is slipping before beginning the grafting process.
Sharpen the grafting knife. Grafting knives are a one-sided, bladed knife that must be razor sharp for proper grafting. To test the blade, carefully shave some arm hair. If the hair comes off easily, the blade is sharp enough. If not, consider having the blade professionally sharpened before grafting.
Using the sharpened grafting knife, make a vertical cut approximately a half inch in length and deep enough to cut into the wood. Make a horizontal cut underneath the vertical cut also a half inch long. When finished, it should appear as an inverted "T."
According to John Begeman, professor at the University of Arizona Department of Horticulture, the best means of creating a bud stick is to select a healthy stick with plump but still dormant buds. These sticks can be found above the leaf petiole where the stem attaches. To protect the stick from damage, "make a horizontal cut across the bud stick about one-half to three-quarters inch above the bud. Cut the bud and a small piece of wood underneath it using a continuous motion. The cut should begin about one-half to three-quarters inch below the bud, and should end at the horizontal cut made above the bud. Lift the chip of wood containing the bud using the leaf petiole (leaf removed) as a handle. This will avoid contaminating the cut side of the bud chip with soaps or oils from your fingers."
Carefully peel back the bark from the "T" cut and slide the chip inside. Push the bud chip down from the top of the "T" toward the bottom until the bark firmly holds the new bud in place. Be sure to position the bud so that it will grow in the same direction as the branch.
Tightly wrap the graft with budding tape. The wrap should be stretched so tightly that it is almost to the point of tearing while wrapping the plant. Continue wrapping until the two are firmly attached to one another. Wrap the graft so that only the bud and leaf petiole are peeking out. This will ensure that the graft remains moist enough for proper healing to take place.
Remove the wrap after a few weeks. If the graft was successful, the bud will have turned into a new shoot.