Ornamental plants are typically grown as houseplants or in flower gardens for display rather than functional purposes. These are grown for showy purposes due to their colorful blooms and rich foliage. These plants are grafted for a number of reasons- the roots are weak and cannot survive in existing soil conditions, to produce larger plants in a shorter period of time or when cultivars are not true-from-seed varieties. Ideally, ornamental plants are grafted in spring, but the procedure can be undertaken in autumn as well.
Select a healthy twig from the ornamental plant for the scion, or the part of the plant that will develop into the stem with leaves and flowers. It should be ¼ to 3/8-inches in diameter, at least a year old and have three or four visible buds on it.
Use a sharp clean knife to make a diagonal cut on the plant in the winter, when it is dormant, that will penetrate the bark and the nutrient dense tissue underneath.
Wrap the scion in a layer of moist saw dust or sphagnum moss and place in a zipper bag in a cool place such as a refrigerator until autumn or spring, when you are ready to graft the plant.
Select a plant that grows well in your climatic conditions for the rootstock- the part of the plant that will develop into the roots. Make sure it belongs to the same family as the scion so the graft is successful. It can be a part of the root, or the stem with roots. The rootstock should have the same diameter as the scion so the union, or the point where they both meet, is strong and the graft is successful.
Sterilize the knife in alcohol and make a 1 ¼-inch nick below the top of the rootstock. Make another downward sloping cut the same length, and remove the piece of wood.
Take your scion wood and make a similar sloping cut on one side of its base, equal in length to the one made on the rootstock, so it fits in it perfectly.
Lower the scion wood into the rootstock, ensuring the cambium tissue- the area directly under the bark, of both pieces meet and form a snug fit. Try to make sure both sides of the stem meet, but a graft will be equally successful even if only one side meets. This point where they meet is called the union.
Cover the union with grafting wax or grafting tape to encourage both the pieces to unite and grow as one plant.
A white callus will form around the graft in four to six weeks, which will split naturally as the plant begins to grow.