A decision as to the number of plants needed must first be made. If a neat formal hedge of clipped evergreens, thick from base to top, is wanted with all possible speed it is wise to be generous with the order, and to allow for a double row of plants, staggered, that is set in this fashion. A double row is also advisable if such hedges as thorn, beech, hornbeam and cherry plum are planted. These hedges are exceedingly useful though they are not evergreen. For the thick mat of stems makes a good windbreak. As a rule, however, their place is along the boundary of a large estate rather than alongside the suburban garden. For a double row hedge the plants are generally spaced about 2 ft. apart in each row, 1 ft. if a very thick hedge is required.
When planting the more expensive type of shrub, such as berberis stenophylla, fewer plants can be used to the yard, in fact from 18 to 24 in. is generally allowed. This brings down the cost of the seemingly expensive hedges considerably, a point to be considered by the owner before he makes his decision.
As soon as the shrubs have been ordered, the site should be prepared. The best method on a fairly open boundary site is this. Begin by taking out a trench 1 ft. deep, and perhaps 2 ft. wide, where the shrubs are to be set. Turn the soil on to the garden side of the trench.
Get into the trench, and take out another foot of the soil, throwing this layer over on to the outer, boundary side. Pile this neatly or it will remain where it is placed without further disturbance.
Break up the lowest layer of exposed soil, using a strong digging fork. Any small weeds, lumps of turf, leaves, rough stones and so on can be thrown into the trench as you break up the subsoil.
If you are not planting lime haters, dust hydrated lime along the soil that was taken from the trench first, using about four ounces to a yard. Naturally, if the subsoil is of chalk, and some of this has been brought to the surface during digging, the lime will not be needed, but on most soils there is no lime left in the top layer. Now return this top soil to the trench, and it will probably be found that it nearly fills it, owing to the increased space that broken soil takes as compared with that which has consolidated. In any case there will be left a shallow trench, filled with good top soil, protected on the outer side of the boundary by a ridge of subsoil.
Use a measuring stick to space the hedge plants evenly, i.e., a stick measuring exactly the space that you intend to leave between the plants. Set out the small plants firmly in the prepared shallow trench, pressing soil well round and among their roots. Small plants are best. It is quite a false idea that tall hedge plants are worth buying. Though bushy plants in pots might perhaps establish themselves quickly and without losses, large plants of privet, lonicera or escallonia generally take so long to get established that parts of the tops die back. The result is a ragged hedge which can only be thickened and improved by drastic pruning. Even then the older plants have not quite the vigour of young specimens, so that in a few years a hedge planted at the height of 9 or 12 in. will far surpass one planted at the same time with specimens of 2 or 3 ft. high.
Firm planting has already been mentioned; it is most important, for loose planting is by far the commonest cause of failure among new gardeners. The shrubs should be set in a prepared hole and the roots spread out as much as possible. Then fine soil should be worked in among the roots, and over them, and trodden firm before the final top layer of soil is added. Plants treated in this way will more readily begin to grow, because their roots will be in actual contact with damp soil.
In a garden where something more than a hedge is required as a boundary screen, a line of formal trees, such as a line of conifers, or an informal belt of mixed trees and shrubs may be considered. On a very exposed site, such as on a seaside cliff, it would be best to plant a hedge in the manner already described — preferably a hedge of some quite hardy nature such as sea buck- thorn, or tamarisk (which revels in sea breezes). This on the extreme outer boundary would sufficiently break the force of the gales so as to afford protection to such trees as might be chosen for the shelter belt.
Trees are planted in the same way as fruit trees or ornamental shrubs, that is in soil that has been dug to a depth of 2 ft. or more, keeping the top layer of soil at the top, but turning this layer over, and breaking up the lower soil well so as to encourage good drainage which is essential for tree cultivation.