After the positions of the trees have been staked out, holes must be dug for their reception. The holes should not be less than one and a half feet each way, and may conveniently be cubical. The larger the holes the better will be the general growth of the plants. They should be filled in with surface soil and allowed to settle for some time before planting. The strongest seedlings in the nurseries should be selected for planting out, and all weakly and defective plants rejected. On removal from the nursery the seedlings are frequently stumped, that is to say the whole of the green top is cut away, and the tap root is severed about 18 inches below ground level, most of the lateral roots being also cut short Mr Tisdall tells me that it is a mistake to cut the tap root and laterals too short. This operation, which at first sight appears somewhat drastic, has great conveniences in practice and is not theoretically objectionable. If the leaves and smaller roots were left upon the plants, both would be found to die back except under remarkably favourable circumstances. Stumps can be used which have grown for two and even three years in the nursery, whereas it would be impossible to transplant seedlings of that age with all their roots and leaves. A good start for the plantation is thus assured, and there should be few failures when proper care is exercised. The earth should be rammed tightly round the planted seedlings or stumps. For early planting, seedlings grown in small loose baskets may be used, as these can be set out earlier than plants grown in the nursery in the ordinary way. The baskets are planted with the seedlings and are allowed to rot in the soil. When this method is adopted it is specially necessary to make sure that weakly plants are rejected.
Planting should of course be carried out in wet weather, and in most countries where rubber is grown this presents no difficulty. Should a prolonged drought follow shortly after planting the young plants may require some protection. This is often best afforded by mulching with grass and leaves, or with anything of the kind that may be available, close round the plants, in order to check evaporation from the soil surrounding the roots.
In Ceylon under favourable conditions Hevea trees will grow in height at the rate of 6 to 10 feet per annum for the first three or four years after planting. In girth the increase may be about 3 to 4 inches per annum during the first few years. After this the rate may be slightly increased until the lateral branches have completely met, and then growth becomes slower once more. The greatest development takes place after the third year. Some of the oldest trees in Ceylon, at 35 years of age, had a girth of over 100 inches, and were about 80 feet in height. In Malaya the average growth of young trees is still more rapid, and it has been stated that the girth of four-year-old trees in the Federated Malay States is generally equal to that of five-year-old trees in Ceylon. The age of the trees is always reckoned from the time of planting, and not from the date of sowing the seed.