Soil and Planting Shrubs
The vast majority of shrubs are happy in good humus-rich, well-drained. Avoid any locations that are badly drained or, even worse, during the winter months. As with all rules there are exceptions, and principal among these are the ‘lime-haters’, that is, the plants that only thrive if grown in soil that is more acidic than alkaline.
Before deciding on what to plant it is a good idea to have the soil analysed. This will not only tell you if the conditions are alkaline, but also if there are any trace elements that are absent.
Among the plants that will not tolerate lime are forms of Camellia, Pieris and Rhododendron. These require acid soil conditions, ideally enriched with leaf mould.
The first thing to consider is how your shrub has been supplied. Those grown in containers can be planted at any time of the year, provided that soil conditions are suitable. It is best to avoid times when the ground is frozen or very wet, or if it is very dry and the weather is hot generally.
Prior to the widespread use of containers, shrubs were supplied bare-rooted during the dormant season; even today some still are. Here, the planting period should be between early autumn and late winter. The same applies for pre-packed shrubs sold in numerous retail outlets. Examine these carefully: if the roots are dry, plunge them in water for an hour or so before planting out.
Another method used by nurseries is to supply evergreen shrubs ‘balled’. These shrubs have been dug up and the rootballs tightly wrapped with sacking or other protective material. It is important that the roots do not dry out during the period that the plants are wrapped and stored. They should not, therefore, come to any harm for several weeks until the soil conditions are suitable. Rhododendrons are often supplied like this.
When purchasing young shrubs it is difficult to appreciate how much space they will eventually need when they’re mature. There is a temptation to plant them too closely, eventually resulting in overcrowding and poor or misshapen growth due to lack of light. If you wish to fill a space quickly or temporarily, rather than choose and plant an inappropriate shrub you should perhaps consider a herbaceous perennial, or even an inexpensive shrub alternative. This can be removed at a later stage, when the priority shrubs have made sufficient growth.
Most container stock is grown in peat-based compost, which can sometimes lead to problems when planting out. The roots suddenly find themselves trying to grow in less hospitable garden soil. This shock to their system can be minimized by using a planting mixture obtained from garden centres, or a home-made concoction of topsoil, peat and a little bonemeal fertilizer, all mixed well.
If, when you remove the plant from its container, you see that the roots are pot-bound, gently tease them apart at the bottom. This will encourage them to establish more quickly.
The planting hole should be larger and deeper than required. Spread a 10cm (4in) layer of the planting mixture in the bottom of the hole and place the shrub over it. There should be enough space in the hole for some of the mixture to be placed around the sides as well. The surface of the surrounding soil should be just slightly raised from the compost level of the shrub, so that water will collect in the ‘well’ that has been created. This will help to prevent drying out in hot weather Firm well around the roots to increase their contact with the soil, and to lose any air pockets, which will cause roots to dry out.
A similar planting procedure is used with balled plants, pre-packaged and bare-root stock. Here again, dig a hole large enough for the roots to be spread out. Work the planting mixture well around the roots, and firm as you go. Tread the soil gently to firm. It is important that the old soil mark on the stem is just below the soil level when planting is finished. Water well.
It is advisable to cut back the branches on bare-rooted shrubs by one third, to help speed their establishment in the soil. Plants purchased in containers do not need this treatment.
Cold winds and severe weather can cause damage to the foliage of some evergreen shrubs when planted in the autumn. This can be avoided by erecting a shelter of polythene sheeting around any that are liable to be damaged. Secure it well, to avoid it being blown away in high winds, and ensure the base is fixed down to avoid draughts.