Budding is a special grafting technique in which the grafted plant is produced from a single bud. As with other techniques of asexual propagation, the resulting plants are clones (genetically identical plants reproduced from one individual entirely by vegetative means). This is the method most commonly used in commercial rose production. The plant being propagated (represented by the bud) is referred to as the scion, while the plant being grafted onto is referred to as the rootstock, or simply stock. A small branch with several buds suitable for budding on it is often called a bud stick.
Successful budding requires that the scion material have fully-formed, mature, dormant buds, and that the rootstock be in a condition of active growth such that the "bark is slipping". This means that the vascular cambium is actively growing, and the bark can be peeled easily from the stock piece with little damage. T budding can be performed on roses most anytime of year on most varieties as they have a recurrent bud to bloom cycle. Here in south Florida, the cooler months tend to be most successful as both the scion and the rootstock are more likely to be receptive.
|Bud sticks having plump, healthy buds are suitable scions. These bud sticks should be on branches that exhibited good growth during the current season, rather than ones from the interior of bushes that have slender stems and closely spaced, small buds. A stem that has just finished blooming and is showing new buds is ideal. Leaves and thorns are removed from the bud sticks. This leaves a clean bud stick from which to cut the bud scion for grafting.|
The bud and a small sliver of the wood underneath it
are cut from the bud stick using a downward slicing motion. The cut should
begin about 1/2 to 3/4 inch above the bud, and should go deep enough into
the wood so that when the cut is finished about 1/2 to 3/4 below the bud,
the bark and a small sliver of wood are cut off. A perpendicular cut across
the bottom of the downward cut will separate it from the bud stick.|
Budding knives must be kept very sharp, so that as little damage as possible is done to the bud. Dull knives strip and tear the wood, leaving cuts that do not heal properly. Buds must be cut from the bud stick just prior to grafting, otherwise they will dry out. Some grafters put the bud in their mouth for the time between when it is removed from the stick and when it is grafted in place, but this practice is not recommended. Speed in grafting is a more suitable solution.
A vertical cut is made on the stem of the root stock. The cut should be deep enough to insure that the bark will separate at the cambium.
The "T is then crossed." That is, a perpendicular cut is
made at the lower end of the vertical cut. In areas with heavy rainfall during
the grafting season, this upside down, or inverted T bud is used to
prevent water or sap from pooling in the graft.
The bark is carefully slipped from the stem of the rootstock exposing a "pocket" into which the bud shield can be placed. Care should be taken not to tear the flaps of bark in the process of spreading them.
If the bark does not slip easily, this indicates that the stock is not in active growth and the process should be conducted later when active growth has resumed.
An alternative method for budding which does not require the bark to slip is the technique of chip budding in which the bud is cut out with a "chip" of the underlying wood. This requires that a chip of corresponding size be cut out of the stock piece in order to align the cambia for proper graft healing.
|The bud shield is carefully slipped in between the bark flaps. The bottom of the bark strip on the bud shield is trimmed to fit tightly against the horizontal cut (the cross of the T) so that the bud fits within the "pocket" snuggly.|
The bark flaps are held tightly against the bud as they are wrapped with parafilm, grafting tape or other suitable closure. This closure must either breakdown by weathering (as parafilm does), or must be removed in 2 to 3 weeks after the union has healed. If the material does not break down, it will girdle the rootstock.
After the union has healed, the upper part of the rootstock plant can be cut away to force the bud to grow (as would be the case in spring budding). If the grafting is done in the late summer, the bud likely will need to overwinter prior to resuming growth. In this case, the upper portion of the rootstock is usually removed during the dormant season, either in late winter or early spring.
After the upper portion of the rootstock is removed, the scion bud grows vigorously.
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