Shrub and Tree Planting Factors: When and Where
Weather is vital to the gardener, yet in no way can it be controlled. So on the basis that if you can’t beat it, join it. It is wise to adapt your activities to take advantage of the climate. For example, if rain is imminent, this is the time to plant out seedlings or sow seed and if a hot, dry, windy clay is forecast, weeds that are already hoed will die and disappear.
Plants can grow and flourish in heavy or persistent rains, but they die in drought. The most perilous time for all trees and shrubs is a period of drought when they have been newly planted. So conservemoisture by mulches and save as much rainwater as possible for use in dry periods. All plants are composed more of water in various forms than of any other substance and nearly all of this moisture is taken up by the plant through its roots.
Frost is considered to be an enemy of the gardener, and so indeed it can be if certain protective measures are not adopted, but it can also be a friend. Nothing is better than a heavy frost for breaking down clay into good, friable, easily worked earth. In winter always try to dig vacant ground and leave the soil in great lumps or clods so that frost, rain and snow can break them down and reduce them to a crumbly texture.
We all know that frost cracks our water pipes because ice expands when it thaws. It does exactly the same thing with the tissues of some of our plants. If the rate of thaw after a frost can be slowed down, damage to the plants will be lessened. Take an early flowering camellia as an example. Plant it in a situation so that it is protected from the warmth of the early morning sun and instead let it thaw slowly in shade. On the other hand, frost can kill a young tree or shrub by depriving it of water. With soil moisture frozen, roots cannot absorb any.
Frosts tend to flow downhill. They will collect in a valley or a depression in the ground. If your land slopes, try to ensure that the lowest part is open and not blocked by a wall or hedge. This way frosts will roll down the garden and cause little or no damage on your land.
Young or newly planted trees and shrubs can be damaged or even killed by sharp frosts and by strong winds. Where this is the case a little protection can save them from both perils. It is possible to make a rough surround for a plant by inserting three or four lightweight stakes into the soil around the plant. Wind string around these to make a small enclosure. Roughly fill this with straw, dried bracken or even sheets of newspaper to keep out frosts and protect against winds. Do this carefully so as not to damage the spreading branches and twigs.
SUN AND SHADE
Light is as vital to nearly all plants as is water, for light helps to create the organic matter of which the plant is made. Lack of light will result in weak, spindly growth. Pale or even white colouring, such as you get when chicory or dandelions are blanched by the exclusion of all light. Lack of light can kill a tree but is more likely in our gardens to lead to a weak or misshapen specimen, for the growth will tend to be in the direction of the strongest light.
Sunlight is also a source of heat and too much of both light and heat can be a danger to many plants, particularly trees and shrubs which have been newly planted and have a root system limited in extent. These roots provide the plant with moisture which is drawn up through the main trunk and its branches to the tiny twigs at the extremes and thus to the leaves, which exude the moisture. If the sun and warmth draw out this moisture, at a faster rate than it can be replaced, the plant will soon be in trouble, which is one reason why it is vital to ensure a sufficient supply of moisture to the roots of young plants. Some trees and shrubs will react to this dangerous water loss by drooping their leaves and others will move their leaves to an angle where the sun strikes less strongly on them. Once root growth is more mature and spreading most trees and shrubs have a better chance of looking after themselves. You can erect temporary screens in the interim while the plants mature: split-cane and greenhouse blinds make excellent screens.
Shortage of light rather than an excess is as a general rule more likely to be the problem in northern Europe. Gardening in a city can bring problems; not only is the quality of light poor because of polluted air. But its direct passage is often obstructed by high buildings. There are fortunately a number of trees and shrubs which will grow happily in shady conditions and it is well to have a look at some of these if you want to plant in difficult conditions of shade, remembering that when the shade is caused by larger trees and shrubs growing above the new planting, these will tend to absorb the major part of the existing plant foods from the soil, so special feeding programmes as well as watering may be necessary.
The laurels are good shrubs for shady conditions. The common laurel, Prunus laurocerasus, is a quick grower; the Portugual laurel. Prunus lusitanica and what is known as the Japanese laurel, Aucuba japonica, with its splendid golden-leaved varieties, are satisfactory subjects for the shade. All are evergreen. Mahonia japonica bealei, with its dainty sprays of yellow, most camellias and the gorgeous winter-flowering laurustinus or Viburnum tinus will all grow well in shade.
Plants that like shade can also be used to landscape a shaded area of your garden which you might wish to use for just such a purpose. This is where shade-tolerant flowering shrubs and weeping subjects can make a perfect-shady corner for sitting in on a hot summer day.
SOIL AND DRAINAGE
All soil began as rock, pulverized through the ages to become no more suitable for plant growth than pure sand. It is the animal and vegetable matter in the soil, the decaying leaves, bones and waste matter of life, together with the bacteria that activate, enrich and re-texture it so that it becomes alive, nourishing and feeding the plants that grow in it. This organic matter, known as humus, is the most important element in all soils. It breaks clown clay and makes it workable. It gives body to sand and enables it to absorb moisture. It invites air into the soil and holds moisture.
The humus in soil is used up where cultivation is intensive and therefore it is necessary to add to the soil constantly. Farmyard manure is a good source of humus, but equally valuable is homemade compost, which after all is no more than decayed vegetable matter of many kinds. Humus also provides the necessary conditions for bacterial activity. It helps to break down the soil into the basic chemicals which are then absorbed by the plant roots. It is helpful to plant growth for you to add these chemicals in the form of fertilizers. They are usually sold as a mixture of nitrogen (N), phosphates (P) and potash (K), often shown on the packet by the letters or by numbers only, indicating the relative proportions of each chemical. These fertilizers are obtainable as a granular or powder mixture or as a liquid. Dry mixtures must be watered into the soil. Apply according to the manufacturers instructions – an extra dose may kill the plant.
It is possible to buy soils of various types, some tailored to specialized uses. A soil for cacti, for example, would contain a high proportion of coarse, sandy material to ensure the necessary sharp. A soil for rhododendrons would be acid. The John Innes composts or soils, devised by the horticultural institute of that name, are blended to a strict formula, sterilized to kill dormant weed seeds and containing fertilizers of three strengths to suit seedlings, medium-sized plants and those that are mature.
Garden soil can vary widely in content, texture, acidity and alkalinity, richness and poverty and it is worth buying a small soil testing kit to discover any deficiencies in different parts of the garden so that these can be rectified. All soils tend to become more acidic as they are cultivated and although this can in some cases be of benefit, in others it can be a serious drawback to good and productive gardening.
Where a garden is created on low-lying land or on a heavy clay soil it can become boggy and wet. Unless a large area of land is involved, it is seldom necessary to go to the considerable trouble and expense of installing special drainage. For the problem can almost always be overcome over a period of cultivation by the addition of such materials as sharp sand and humus and simply bythat will absorb and use up most of the excess wet.
Various types of soil conditioners can be bought which are claimed to break clown unworkable clay into friable soil and generally to improve the texture, productivity and drainage of problem soils. Some of these products, usually based on gypsum or on seaweed, can be helpful (though expensive) but none takes the place of the proper cultivation of the soil, planting it with suitable subjects and tending it regularly.
Make sure you understand the needs of a plant before you put it in its permanent position; for example, never plant willows near a house, a wall or near underground. Its far-reaching roots can cause damage in its search for moisture
WHEN AND HOW TO PLAN
The trees and shrubs you buy can come in two forms, either dug from the nursery soil and delivered to you with bare roots usually wrapped with straw and hessian, or container grown, the roots still in a plastic pot of some sort. There is an important difference. The first must be dug from the soil and planted in your garden when the plant is dormant, during the winter months. Container-grown plants can go into the soil at any time of the year. More and more container-grown plants are being chosen because they can be seen growing with foliage and flowers.
Plant your bare root tree as soon as you can after receiving it so long as the weather is suitable, without frost or heavy rain. Dig a hole in the selected site, making it a little larger and deeper than the roots. While you are preparing the hole stand the young tree in a bucket of water for an hour or two to plump up the roots. Have ready some good planting soil, a mixture of some of the soil from the hole, some peat or homemade compost, a little coarse sand or perlite to improve the drainage and a handful of a gentle fertilizer such as bonemeal. If the tree looks top heavy and could be rocked by the wind, insert a strong stake before planting. Hammer it well into the soil in the base of the planting hole so that it stands firmly fixed and perpendicular. Then take the young tree or shrub and examine the roots carefully, cutting away with secateurs any broken or damaged roots (1). Stand it in the planting hole and sift the soil gently over the roots, making sure that no air pockets are left (2). Firm the soil around the roots as you go and when the hole is half filled, tread the soil down with your foot. Continue adding the soil, making sure that when completed it will come exactly to the previous soil mark on the stem (3). Finish off by firming the soil down with your foot and leaving the plant standing in a slight saucer. This aids watering in future (4).
Fix the tree to the stake, preferably using special tree ties, but otherwise use string, rope or some material such as an old nylon stocking, something that will hold firm without rubbing or chafing. Water the young tree thoroughly, sprinkling the foliage too if it is an evergreen and making quite sure that all the soil in the planting hole becomes moistened. Do not let this soil become dry for the first few months and examine the stake and tie when March winds begin to shake the plant in the soil.
To plant a container-grown tree follow exactly the same procedure except that when the plant is removed from its pot put the whole root ball into the planting hole, disturbing as little as possible. Try to firm the planting soil around the root ball to get much the same texture.
The main beauty and benefit of growing trees and shrubs is that they demand little attention after they have been put into the soil. But some of these plants are expensive and deserve to be grown as well as possible to give a good return on your investment, so it is well to ensure that nothing goes wrong.
The importance of seeing that the newly planted shrub does not dry out has already been mentioned. Make sure that the whole plant, including all the leaves from tip to base, has been thoroughly wetted at each watering just as it would be by rain and unless you are quite sure that the soil is moist, give at least 10 litres (2 gallons) each time. It is helpful to apply a monthly all-over spray with foliar feed mixed to the manufacturer’s instructions.
Keep the soil at the base of the plant free of weeds, but do not disturb the soil surface too vigorously as the young roots should be allowed to settle into the soil and grow rapidly. If weeds are removed by hand each time the plant is watered then the soil surface should remain clear and uncluttered. In particular avoid tap-rooted weeds such as dandelions and remove these completely including every piece of root while they are young.
Once the young plant has been in the soil for a couple of months and is obviously happy and doing well, it will normally be possible to ease off the watering programme. You can then kill several birds with one stone by applying a good mulch to the soil right around the plant. First make quite sure that the soil is moist, give it a good watering even when this does not really appear to be necessary. Then apply the mulch to the soil around the main stem. Do not allow it to touch the stem of the tree or shrub, but encircle it entirely. A bulky mulch such as farmyard manure or homemade compost can be up to 15cm (6in) deep and a mulch of peat or shredded bark about half this. If you have nothing else, grass mowings make an admirable mulch so long as the grass has not been treated recently with a hormone weedkiller.
A mulch of this nature will do much to retain the moisture in the soil around the roots and at the same time keep them cool. The mulch will gradually disintegrate and disappear into the soil, enriching it and improving the texture. Worms and bacterial growth will be encouraged. Weed growth will be smothered almost completely and any weeds that do appear can be easily removed from the loose and open soil.
Remember that however well or thoroughly you mulch your new tree or shrub this is an activity designed to improve the soil structure rather than feed the plant, so in the early spring try to go around all your trees and give them each a handful of fertilizer. If this is powder or granular, sprinkle it in a circle about 30cm (12in) around the base and very lightly spike this in with a fork or hoe it into the top soil, being careful not to go too deep in case any roots are damaged.
With many trees and shrubs it is unnecessary to treat against pest and insect attack, but look carefully at your own materials each spring and see if there are signs of eaten leaves or other disfigurement and if so spray at once with an appropriate pesticide.
PLANTING A HEDGE
The technique of planting a hedge is exactly the same as that used for planting any normal tree or shrub except that you plant a series of them in a line. Whether straight or curving. So instead of digging a single planting hole , or even a series of planting holes, the easiest way is to dig a trench along the required line. This must be wide enough to take a double row of shrubs. Staggered, planted in effect at the top and bottom angles of a letter W. A single row may be suitable if you only want to provide a light screen.
To be effective your hedge must live for years in the same position. It should be clothed in foliage from top to bottom. It should look attractive in all seasons. It should grow quickly and evenly, but not so quickly that too much time has to be given to clipping or otherwise controlling.
First of all make sure that the soil in which the hedge is planted is rich and full of nourishment. If possible place a good layer of farmyard manure or similar material in the bottom of the trench into which the roots can grow and incorporate a handful of bonemeal or other slow-acting fertilizer into the planting soil.
To ensure foliage from ground level upwards it will be necessary to encourage new growth, so cut back the top of the young trees or bushes by about a half soon after planting, but do no more trimming in the first year. In the second year let the hedge grow upwards and begin to trim the sides to get the required shape and to thicken up the growth in the vital centre. Do this two, three or even four times in the second and third years because it really is important to achieve the right shape, tapering very slightly towards the top. This ensures that any substantial fall of snow cannot lie too heavily on the somewhat fragile top and so break or bend the branches.
When the hedge is beginning to reach the desired height, pick a few places along its length where you can measure the height. You may find the best way is to make a special measuring pole. If you trim these places accurately then you can tailor the remainder of the hedge to fit in and so obtain a pleasant evenness. If you wish to wave or undulate your hedge, then you will have to allow certain portions to grow longer than others. The best time of year for trimming an established hedge is in the late summer. Aim always to cut back to within a few centimetres or less of the previous year’s growth. Use good shears or electric clippers and for ease of clearing up, work above a long plastic sheet placed on the ground at the base of the hedge. You can then collect the trimmings all at once instead of having to rake or sweep them into piles.
DISEASE AND PEST CONTROL
If the healthy trees and shrubs are planted in the right way. At the right time and in the right place, they should normally have years of healthy and productive life ahead of them. They will be able to shrug off most attacks of any diseases that come their way and will not succumb to the depredations of insects. Occasionally a freak of weather or circumstances may so weaken a plant that a disease or pest attack can then enter and cause severe damage, but it is impossible to guard against this.
An experienced gardener will quickly see from the appearance of the plants if there is something seriously wrong and will then examine, diagnose and treat accordingly. A few trees, the various types of flowering cherries are examples, tend to suffer from attacks of certain diseases and annual spraying will prevent this. Cherries are sometimes disfigured by the ugly blisters of peach leaf curl, a fungus disease that is controlled by a spray with Bordeaux mixture or dithane. Occasionally a rare or unexpected infestation of aphids or caterpillars may take place. This will probably not seriously damage a healthy tree but will certainly disfigure and perhaps weaken it, so a clearance spray is advisable.
As a general rule tree and shrub leaves that have holes or nibbled edges are an indication of beetle or bee attack which on most occasions is not of great significance. More important is the complete disappearance of a leaf, with only the petiole remaining. This indicates serious caterpillar infestation and the tree should be sprayed at once before damage goes too far. A systemic insecticide, one which is absorbed by the leaves and retains the poison to affect any insect or caterpillar which eats or chews the leaves even a few weeks later, is the sensible type to use here.
Silver leaf is one of the few important diseases that affects the flowering cherries, some willows, hawthorn, laburnum and others. It usually begins by fungusentering a wound, so if you consider a cherry (usually quite unnecessary) make sure that the wound is cleaned and painted with Arbrex or a similar protective disinfectant. Silver leaf shows by the characteristic colour of the leaf and by a brown core in the affected shoots. Cut right back to healthy wood and clean and paint the wounds carefully.
Acid-loving plants such as rhododendrons and ericas sometimes show their unhappiness with an alkaline or limy soil by producing pale, yellowing leaves instead of the normal healthy green. This is a sign of chlorosis, a lack of iron. It can be prevented by incorporating acid peat into the soil and by spraying with a chelated iron compound to provide the necessary element.
There are many pests and insects that attack garden plants and it is not always easy to identify them or to tell them apart. But in general they will all succumb to a pesticide applied in the form of a liquid spray or a powder, either to the plant itself or to the soil at its base. Make sure that the spray or powder reaches every part of the plant that might be affected. Some pesticides are known as persistent or systemic because they are absorbed by the plant system and live in the sap for up to a month or so, which means that any pest eating any part of that plant will be killed. Others are contact killers only, or have a ‘knock down’ effect which merely incapacitates the pest for a period, so when using this type of insecticide it is always advisable to re-apply the spray or whatever after two or three days to make sure that the pest is cleared.
Always remember that pesticides are necessarily poisons. Store them and use them with care and responsibility. Never use them in a high wind. The best time of day is the still of the evening when the air is quiet, when the sun is sinking, when the bees and beneficial insects have left for their homes and when you, the gardener, are in the physical and psychological state of being ready to knock off your garden work and wash thoroughly and change your clothes.