Climbing and Wall Plants
Walls in a garden provide an opportunity for growing some special plants. Most walls provide shelter and so some extra warmth which may enable a plant to flourish in a district with a colder climate than its native country. For instance plants from the Mediterranean region will grow well in many parts of Britain against a south wall.
Climbing plants are those which have a natural means of supporting themselves, such as ivy (by its aerial roots), Boston ivy, often incorrectly called Virginia creeper (by its adhesive pads at the end of tendrils), honeysuckle (by its twining stems) or clematis (by its twining leaf stems).
The term is also used to cover many other plants which can be fixed to the wall artificially, for example tied in to a framework. Among these are the so-called climbing, which if grown in the open would make an untidy, sprawling bush like a blackberry, and also many less hardy shrubs which are trained against the wall, but which would make a bush or small tree if grown in the open.
Many of theare indispensable to cover a large unsightly wall. Familiar examples are Boston ivy, Parthenocissus tricuspidata, which provides a wonderful display of colour just before leaf fall, or the various forms of ivy, Hedera helix. Ivies, being evergreen, are valuable in providing colour all year round, those with yellow or white leaf variegations being of particular value in the dull days of winter. It would, however, be a waste of a good opportunity to use only plants such as ivy to cover a wall; a varied selection of other ornamental plants will bring interest at different times of the year.
The walls of houses or boundary walls provide ideal positions for climbing and other plants, including fruit trees, but one must always estimate the vigour and size to which the plant will eventually grow before planting, and consider the possible effect on the house. In most cases it is undesirable to have climbers growing too high, for with these it is difficult to prune and tie in the new growth; they may grow over windows, obscuring the view into the garden, and into the roof gutters causing blockages. Plants with a very strong root system can damage the foundations of the house if planted against a wall. Therefore the selection of the most suitable type of plant for the right position is most important.
On the whole, climbers, especially the more vigorous ones, are not as satisfactory as shrubs for covering walls of moderate height. In many cases they have a strong tendency to climb to the top of the wall leaving the lower parts bare. However, they can sometimes be trained along the top of the wall, leaving the lower spaces for shrubs. As I have already said, the great value of walls is not in providing accommodation lor climbers alone, but also in affording conditions that enable beautiful shrubs, which are tender in the open ground, to grow successfully.
Soil preparation and planting
For plants that are to be grown on boundary walls, no newor special preparations will be needed, especially if there is already a border in front of them, and where the soil is cultivated. Against the walls of houses or other buildings where the soil is often very poor, or where a gravelled or paved path is so close that there is little or no space for soil, then a considerable amount of preparation is necessary.
A space 1.5 to 2 feet (45-60cm) wide and as much deep should be made at the base of the wall and filled with good top soil. If this is not available, dig in some well-decayed manure, compost, leafmould, rotted straw or peat moss, any of which will be of considerable help in improving the soil. On a heavy clay soil, it may be necessary to add a certain amount of coarsematerial, in addition to some well-decayed compost, leafmould or coarse peat moss which will help to increase the aeration and improve the drainage of the soil.
The ideal soil is a good light alluvial loam to which is added a quantity of decayed leaves or peat moss. If the soil is free from lime chalk, this mixture will suit a wide variety of plants, including the peat loving kinds.
Once the soil has been prepared and improved in structure, it should be levelled and firmed by careful treading before planting. When the plant is taken from its container, the roots should be disturbed as litttle as possible. When, as sometimes happens, a plant has remained in the pot too long and the roots have become very congested and formed a ball, try to open out the roots a little before planting, although too much root disturbance can check the plant’s growth. Plants which have become very pot bound or root restricted rarely grow away so freely as those which have a less cramped root system. Make sure, when buying plants, that you choose those with deep green leaves rather than those showing early signs of starvation, such as leaf yellowing. It is important to make sure that the soil is thoroughly moist at planting time. If necessary, soak the plant overnight in a bucket of water before planting.
Dig a hole wide enough and deep enough to take the roots, and plant with the soil level at the same place on the stem as it was in the container. Firm the soil around the roots.
After planting, the young plant should be secured to a strong stake or some other means of support, to prevent it being blown about by the wind. A good mulch of well-rotted straw, manure, orround the base of the plant will help to conserve moisture and to prevent drying out of the soil during periods of drought. In its first growing season it may also be necessary to give the young plant a good watering in dry periods. Often the ground at the base of the wall or fence becomes very dry through lack of adequate rain, and it is essential to keep the soil damp by watering.
As most plants are grown and sold in containers, planting can be done at any time of the year although autumn or early spring is to be preferred.