Propagation methods
Jujube wood is 2 to 3 times harder than other fruit trees like apple and peach. A sharp knife is required for jujube grafting. The method of grafting will depend on the size of the scion and rootstock and the time of the year (dormant or active growing season). By using a combination of grafting methods, you will be able to use most of your available scionwood and rootstocks of varied sizes. Most growers in Western Australia use wedge grafting or budding. Bark grafting or whip grafting is used in the United States. Cleft grafting is the preferred method in China.
Grafting tools
Basic tools required for grafting jujubes:
- Sharp grafting knife
- Secateurs for cutting scionwood and rootstock
- Hammer or mallet
- Grafting tape
- Labels
- Grafting wax (if using)
Wedge/cleft graft
Wedge grafting is done in late winter or early spring before the bark begins to slip. The scion and the rootstock should have a similar diameter. The base of the scion is cut into a wedge shape. The top section of the rootstock is removed and a vertical cut made into the stem around the depth of the wedge. The wedge is carefully inserted into the cut, matching the cambium layer, which is the thin growing layer just inside the bark. The union is then wrapped firmly with grafting tape.
Bark grafting
As bark grafting depends on the bark separating easily from the wood it can only be done after active growth of the rootstock. The best time is a few weeks after bud break. It can be done later in the growing season, but less vegetative growth will be obtained.
With jujube’s thin bark and dense wood, several cuts are needed to expose a smooth, 2.5 cm or longer section of the scionwood surface. A small cut on the backside is then made to expose the cambium layer. Select a smooth surface close to the ground on the rootstock, remove the part above it with a horizontal cut, and make a vertical cut on the bark until you reach the cambium layer. Loosen the bark on both sides and slide the scion into it.
Wrap the graft union with grafting tape and make sure all the cut surfaces are covered. Make sure to wax/seal the top end of the scion or cover it with grafting tape if you live in a hot climate. Make sure you label the plant to identify the cultivar. See ‘Jujube grafting’ for more details and a video.
Whip grafting
Whip grafting can be done both in the dormant season and the growing season. When whip grafting, the diameters of the scionwood and rootstock must match.
It is particularly useful for grafting relatively small material (0.5 –1.5 cm in diameter). It is highly successful if done properly as there is substantial cambial contact, leading to quick healing and making a strong union.
The procedure involves cutting one side of the scion to make a smooth surface then making a back cut about one third of the way from the top. A similar cut is then made to the rootstock and the scion is placed onto the cut and sealed or wrapped in grafting tape. See ‘Jujube grafting’ for more details and a video.
Bud graft
The best time for successful budding is during the active growth period. This is when the bark will easily separate from the wood in both the scion and rootstock.
T-budding
Successful T-budding requires that the scion material have fully-formed, mature, dormant buds, and that the rootstock is in active growth. This means that the vascular cambium is actively growing, and the bark can be peeled easily from the stock piece with little damage (commonly referred to as the bark ‘slipping’). If the bark is too tight that it has to be forcibly pried loose then the chances of the bud healing are poor.
T-budding is generally limited to stocks that are about 6–25 mm in diameter. The bud is inserted into the stock 5–25 cm above the soil level in a smooth bark surface.
The bud and a small sliver of the wood underneath it are cut from the scion using an upward slicing motion. The cut should begin about 1–2 cm below the bud, and should go deep enough into the wood so that when the cut is finished about 1–2 cm above the bud.
Budding knives should be kept very sharp, so that as little damage as possible is done to the bud. Buds must be cut from the bud stick just prior to grafting, otherwise they will dry out.
A vertical cut is made on the stem of the rootstock. The cut should be deep enough to insure that the bark will separate at the cambium. A perpendicular cut is made at the upper end of the vertical cut to make a ‘T’. The bark is carefully slipped from the stem of the rootstock where the bud is placed. If the bark does not slip easily, this indicates that the stock is not in active growth and the process should be conducted later.
The union is then wrapped with grafting tape or budding rubbers. This closure must either breakdown by weathering or will need to be removed in 2 to 3 weeks after the union has healed.
Chip budding
Chip budding is a form of grafting where the scion is reduced to a small size with only one bud. It can be used when the bark is not slipping – early in the spring before growth starts or during summer when active growth has stopped early due to lack of water or other factors.