The planting season for leaf-shedding shrubs extends from October to March, depending on the weather, and even into April if March is exceptionally bad. Evergreens are best planted either in September, so that their roots can have a chance to become active before winter sets in, or in April or early May, when root growth should start immediately, preventing the loss of leaves. If May is a hot, dry month, newly-planted . evergreens may need overhead spraying each day during May and June to prevent leaf-loss, an operation that is best carried out in the cool of the evening.
The improvement of the soil before planting is very necessary. The actual planting may be done at any time except when the ground is frozen, snow-covered or so rain-sodden that it is difficult to work. It is worth making preparations beforehand by keeping on one side, under cover, a supply of that is easily workable and can be put around the roots when planting. It can be kept, until required, in a shed or out- house or covered with plastic sheeting. It is useful to add bonemeal at the rate of about ¼ lb to a barrow-load of the mixture. Even on lighter soils, or when planting is done in drier weather, bonemeal should be forked into the soil as it is an excellent, slow-acting plant food.
Small shrubs can be planted by one person but large plants may need two people, one to hold the shrub upright while the other returns the soil round the roots and firms it. Depth of planting is important and in general the soil mark on the stem acts as a guide to planting depth. Lavenders, ericas, callunas, , , , Spiraea bumalda and other plants that make spreading clumps, may be planted a little deeper to encourage clump formation. Large specimens, with a big root formation, should be shaken while planting to ensure that soil is properly worked in among the roots to leave no air gaps. Broken or damaged roots should be cut back before planting.
The planting hole should be made sufficiently large to enable undamaged roots to be spread out properly without being bent back on each other. Spreading the roots out in this way will also help to provide firm anchorage for the plant, although trees and shrubs grown on a stem should be provided with a stout stake firmly driven into the centre of the hole before planting is started. To plant firmly is essential, though this does not mean trampling round the shrub so hard that roots are broken off. Some plants, notably rhododendrons, arrive from the nursery with their fibrous roots balled in sacking. In such instances the roots should not be spread out and all that is necessary is to loosen the sacking, plant the roots in a hole large enough to take the ball, and firm the soil round them.
If the root ball looks as though it will disintegrate when the sacking is removed from around it, the plant can be put into the ground, sacking and all, merely removing the string after planting. The sacking may be pulled away after planting, but if it does not pull away easily it can be left and will soon rot down. The roots will also grow up through the sacking as it rots.