The following methods have all been used to propagate chestnuts with mixed success. Once a successful method is found, stick to it, because part of the failure to produce trees satisfactorily comes from changing a proven practice.

Rootstocks
Seedlings are used as rootstocks for propagation of chestnuts. Collect seed at harvest time and keep it moist until germination takes place. Place the seed between layers of sand or a similar medium and water it regularly. Keep the medium moist but not wet.

Plant the germinated seeds 50mm to 80mm deep and 200mm to 250mm apart in nursery rows which are between 0.75m and 1m apart. A seedling normally takes two years to grow big enough for budding or grafting (at least 10mm in diameter, or pencil thickness).

Budding and grafting
Some of the most common methods of budding and grafting chestnuts are:
The whip-tongue graft (Figure 1) can be used when the stock and scion are about the same thickness or when the stock is slightly larger.

When using this method to propagate chestnuts, let the stock fully develop its leaves, and use dormant scionwood cut in winter and stored under refrigeration.

Carry out whip-tongue grafting in spring after the risk of frost damage has passed. First cut the scion and the stock with one long sloping face. Make another cut in the face of these cuts to form tongues which interlock when the two pieces are placed together. Tie the graft in place with plastic tape.

Budding
Budding is the most common and popular method used to propagate chestnuts. Budding with shield or "T" buds (Figure 2) can be carried out. The buds can be dormant or green. Dormant budding is carried out in spring after the stock has come out into full leaf. The bud sticks are collected in winter and stored under refrigeration. When green buds are used, the best time for budding is during late February-early March. Shield budding can be carried out at all times when the bark slips or peels well.

Make a "T" cut on the bark of the shoot or stock to be budded. Make a cut about 35mm long lengthwise along the blade under the stem.

Cleft Grafting
Cleft grafting is used when the stock is of much greater diameter than is the scionwood. It is a very old method that is rarely used now. Split the trunk at right angles to the bark with a cleaver or heavy knife and cut a scion to a chisel shape and push it into the cleft. Make sure that the cambium layers of actively growing cells (which lie between the bark and the wood on both the stock and scion) are in close contact. Seal the graft with grafting wax. The two flaps of bark so created can then be lifted away from the underlying wood with the part of the budding knife provided for the purpose.

Next cut the bud. Hold the bud stick upside down and use a sharp knife to make a cut starting 10mm below the bud. Drawing the blade under the bud with a shearing motion and bring the blade to the surface about 10mm above the bud. Hold the bud by the short stub of the leaf stalk or petiole and push it down between the flaps of bark on the stock.

The small piece of wood at the back of the bud does not have to be removed before the bud is inserted in the stock. Make sure that the cambium layers behind the bud and on the exposed surface of the wood of the stock are in close contact.

Tie the bud in place with rubber or plastic tape to keep the union airtight and to exclude rain. Plastic tape is good for tying buds because it is flexible and does not cut into the stock. It will eventually perish and fall away and therefore does not need to be removed. It does not matter if the plastic tie completely covers the bud, except of course for spring budding, when the bud should be free.

The remaining part of the leaf stem (petiole) can be used as a test of the success of the operation. The bud has usually taken if the leaf stem comes away freely from the bud eight to ten days after the operation. The bud is probably dead if the leaf stem remains attached.

Cuttings
Propagation of chestnuts from cuttings has been tried with limited success. The most successful method reported so far involves taking cuttings in December. A sliver of bark was removed from both sides of the base of the cutting that was then dipped in a 0.75% I.B.A. solution. The cuttings were then placed under mist. Some success has also been gained by treating hardwood cuttings with hormones and placing them in a propagation frame supplied with bottom heat.

Addendum by: David Mclaren - Bark Grafting

1. Use only good quality scionwood that has been stored properly.
2. Do not damage chestnut buds as each node has only one bud. The scion will not grow if this is damaged.
3. Graft only high quality stocks because poor stocks often result in poor takes.
4. Make sure all tools used are clean and sharp.
5. Take care with all operations; speed does not ensure success.
6. Look after the nursery before and after grafting.

Bark Grafting
Another technique of grafting which is particularly suitable to re-working older trees is known as Bark Grafting. In this method, the branch or even trunk is cut transversely (optimal diameter 100-150mm) with a slight slope in the case of the trunk to allow run-off from the cut surface. The graft is inserted between the inner aspect of the bark and cambium layer.

The Process:

1. To prepare the graft for this procedure, select scion wood about 10 mm in diameter and round in cross-section.
2. For the right-handed, the scion is held across the body in the left hand, with the thicker end pointing towards the operator's right elbow.
3. The long oblique cut in the scion wood is best made by drawing the blade firmly to the right. This movement occurs almost entirely at the shoulder. The elbow bends slightly as the cut proceeds. There is no movement at the wrist or hand joints.
4. At the commencement of the cut, the scion wood rests lightly against the extended right thumb which acts as a guide, rather than a resistance against which the cut is made.
5. The best knife for this is a grafting knife which has a sharpened bevel on only one side.
6. The cut surface on the scion wood is about 25 mm long and the angle of the cut is 10-15°.
7. To insert the graft, a small vertical cut is made in the bark, which is then prised slightly away from the cambium layer.
8. The graft is then pushed down so the entire oblique cut surface lies firmly against the cambium layer.
9. Grafts are normally inserted about 100 mm apart and have a minimum of 2 buds.
10. Once the required number of grafts has been inserted, the cut surface of the stock and the tip of the graft are coated with sealing material and any gaps between the bark and the cambium resulting from insertion of the grafts are also closed with similar material.
11. The grafts are bound in place as firmly as possible with grafting tape and this may be done before sealing the surface.
12. Finally as the canopy has been removed it is wise to protect the bark of the trunk from sunburn by painting with white water based paint or applying sisalation.

These grafts may grow very rapidly, making them prone to breakage in strong winds. This can be circumvented by trimming as they grow. There is normally no urgency to remove the grafting tape. This can usually be left until the following winter.

One occasional hazard to this type of graft is the predilection of kookaburras for perching on the cut surface of the trunk. This can lead to destruction of these grafts.

For the enthusiast: "The Grafter's Handbook" by RJ Garner published by Cassell.

Estimated Production for Grafted Chestnut Trees

This scale applies to grafted trees. It was lagged by a five year period for non-grafted trees assuming that non grafted trees start bearing at ten years of age. The scale is considered to be conservative as some of the new grafted tree varieties appear to be bearing up to three times the scaled amount for any given age.