Propagation of the litchi is commonly effected by two means : seed, and air-layering (known in India as guti). Higgins writes on this subject:
"As seeds do not reproduce the variety from which they have been taken, and as the seedlings are of rather slow growth and require many years to come into bearing, it has for many years been the custom in China, the land of the litchi, to propagate the best varieties by layering or by air-layering, a process which has come to be known as 'Chinese layering' and is applied to many kinds of plants. In air-layering, a branch is surrounded with soil until roots have formed, after which it is removed, and established as a new tree. In applying the method to the litchi, a branch from 3/4 to 1 1/2 inches in diameter is wounded by the complete removal of a ring of bark just below a bud, where it is desired to have the roots start. The cut is usually surrounded by soil held in place by a heavy wrapping of burlap or similar material, although sometimes a box is elevated into the tree for this purpose. Several ingenious devices have been made to supply the soil with constant moisture. Sometimes a can with a very small opening in the bottom is suspended above the soil and filled with water which passes out drop by drop into the soil. Again, sometimes the water is conducted, from a can or other vessel placed above the soil, by means of a loosely woven rope, one end of which is placed in the water, the other on the soil, the water passing over by capillarity.
"Air-layering is commenced at about the beginning of the season of most active growth, and several months are required for the establishment of a root system sufficient to support an independent tree. When a good ball of roots has formed, the branch is cut off below the soil, or the box, after which it is generally placed in a larger box or tub to become more firmly established before being set out permanently. At first it is well to provide some shade and protection from the wind, and it is often necessary to cut back the top of the branch severely, so as to secure a proper proportion of stem to root."
Regarding methods of propagation employed in China, Groff says: "I have never seen a budded or grafted litchi tree, and I understand it is never done. Litchi trees are either inarched or layered, the latter being the most common and most successful. If inarched it is on litchi stock. The common practice in inarching is to use the Loh Mai Chi variety for cion and the San Chi for stock."The method of layering mentioned by Groff is that described above. Inarching is treated in this volume in connection with the propagation of the mango. It is a tedious process of grafting little used in America, but more certain than budding and other methods.
Litchi seeds are short-lived. If removed from the fruit and dried, they retain their viability not more than four or five days. If they remain in the fruit, however, and the latter is not allowed to dry, they can be kept for three or four weeks. In this way they can be shipped to great distances, or they may be removed from the fruit, packed in moist sphagnum moss, and allowed to germinate en route. Some of the choice grafted varieties, such as the Bedana of India, do not produce viable seeds.
Higgins recommends that the seeds be sown in pots sunk in well-drained soil. They should be placed hortizontally about 1/2 inch below the surface of the soil, and after they have germinated the seedlings should be kept in half-shade.
Attention has recently been given to the possibility of grafting or budding the litchi on the longan (Euphoria Longana) and other relatives (see below). Higgins has successfully crown-grafted the litchi on large longan stocks. He says, "Repeated experiments with this method have shown that there is no great difficulty in securing a union of the litchi with the longan. A noteworthy influence of the stock on the cion should be mentioned here. The growth produced is very much more rapid than that of the litchi on its own roots, and in some cases the character of the foliage seems to undergo a change." Additional experience is required, however, to show the practical value of the longan and other stocks. The field is an interesting one, and important results are likely to be secured.