CHOOSING NATIVE HEDGE PLANTS

The correct mix will depend on your soil and site conditions and varies around the country and from site to site. The tableabove may be of help to you.

Hedging mixes are often around 50% hawthorn with the other half made from a mix of plants suitable to the conditions. You can see from the table however that hawthorn is not suited to wet or shady conditions. For these sites it may be better to use a large percentage of blackthorn. It is often a good idea to look at the hedging which thrives in your neighbourhood to see which plants are likely to do best.

STAKING A TREE

For very large trees, say those over 30cm girth (girth is the circumference one metre above the ground for a single-stemmed tree), special staking methods may be needed which can only be undertaken by professionals. For smaller trees however it is usually practical to undertake staking oneself. The basic intention is to stop the root system of the plant from moving in the wind whilst allowing the trunk to flex. It is also important to prevent the roots from being broken by the stakes during planting.

One modern way to approach staking is to think of the stem and branches of a tree in a similar way to the muscles of an animal's body - they are both strengthened by use. Thus allowing a tree to move in the wind without allowing the roots to move is likely to create a stronger tree in the long term. For trees with clear stems in situations of normal wind exposure a tree should be staked with a single stake driven in at 45degrees to the vertical and crossing the tree trunk about 450mm or 18inches above the ground. The stake should be driven in outside the rootball. A rubber tree tie should be tied round the tree and attached to the stake and a rubber cushion placed between the tree and the tree tie. These ties will need to be inspected each year and loosened as the tree grows.

In very windy siuations or for larger trees, say greater than 20cm girth, two short stakes with a wooden cross piece are best used. The cross piece has a rubber cushion attached between it and the tree and rubber tries are used to bind the tree to the cushion.

Very large trees may need ground anchors, or bracing using wires attached to the branches of the tree, but these are more jobs for professionals.

WHAT DO THE SIZES OF TREES LISTED IN CATALOGUES MEAN?

Trees in the UK are usually listed by trunk size and by size of container. For instance a tree listed as a 12-14 is a tree with a single stem. The girth (circumference of the stem measured 1metre above the ground level) is in the the range 12-14cms. This girth is about three times the diameter at this point. By happy coincidence, for quite a lot of these standard trees (a standard tree has a clear stem up to at least 1.8metres or 6ft with a formed head above) the height of the tree in feet is close to the girth in centimetres. So a 12-14cm girth tree is likely to have a height of around 12-14 feet. Of course this is not an absolute rule.

Sometimes trees are sold with several stems (called multi-stemmed) and these usually have an overall height listed in a catalogue instead of a girth.

Pot sizes are often given but it may be hard to imagine them. Start with the information that a standard bucket is around 10 litres. Trees in pots up to sizes of about 50 litres can often be moved by one strong person and up to around 75litres by two people. Large trees in pots bigger than this will usually need machinery to move, lift and plant them and may weigh a lot. For instance a specimen tree in a pot of 350litres may weigh in the range of 350kg.

To give some idea of pot sizes, a 70litre pot will usually be around 45cms high and 50cms diameter and a 250litre pot may be 65cms high and 70cms diameter.

CHOOSING A HEDGE

Hedges are part of our landscape and part of our gardens. We use them to give us privacy, to mark out boundaries, to keep animals in or out, and to provide habitats for wildlife. Sometimes we want them to frame a view, hide an eyesore or form a backdrop to our planting.. They may also form windbreaks, cut down noise or keep out unwanted intruders. For all these purposes it is worth planting the right varieties for your conditions or use. Plant the wrong hedge and you may have years to consider your mistake and more years to put it right.

There is a large variety of different plants suitable for hedging. Below we give a few suggestions about the basics.

FORMAL AND EVERGREEN HEDGES

Although an established deciduous hedge can be an effective screen and windbreak, evergreens are often faster and more complete. They tend to look more formal and give a better backdrop to planting displays.

Conifers such as Leyland Cypress, Lawson Cypress and Western Red Cedar can grow quickly and make a very dense and uniform screen. Although Yew is slower it makes probably the best formal hedge and can be cut to almost any shape. All parts of it except the red of the fruits are poisonous so it should never be planted where animals graze. Evergreen hedges over 2m high may be subject to objections in the United Kingdom by neighbours and the local authority who may make you reduce their height.

Other evergreens. Box are classic hedging and edging plants more appropriate for lower hedges than are conifers. Holly, Eleagnus, Euonymus, Laurel, Aucuba, Berberis, Bay, Privet, Pyracantha,Griselinia, Viburnum tinus and Lonicera nitida are also very useful and tough though they suit formal clipping to different degrees. Other shrubby plants such as Choisya, Rosemary, Lavender, Osmanthus, Pittosporum, Hebes, Escallonia, Cotoneaster and Abelia may be used for less formal hedging or for lower hedges. They will need to be fitted well to the particular conditions.

DECIDUOUS HEDGES

Gardeners have a large range of woody plants suitable for mixed or single species hedges. We may wish to create many effects- successive flowers, intruder proof thorns, a wildlife habitat, fruits etc. All plants have preferences in the conditions in which they thrive. They may prefer sunny or shady, wet or dry, limy or acid, light soil or heavy, exposed or sheltered. Often they can be left informal (not clipped too rigidly) but most hedges will grow more densely and be more effective barriers if they are clipped at least once a year. Amongst the more effective deciduous hedging plants are Beech, Hornbeam, Forsythia, Ribes (Flowering Currant), Elder, Willow, Blackthorn, Hawthorn, Philadelphus, Fuchsia, Dogwood and Flowering Quince. Many of these can be combined with each other and with evergreens.

Country hedges. Landowners and farmers are encouraged by the Government to plant native hedges in keeping with local traditions. In some cases Countryside Stewardship grants are available for this. They usually recommend at least five local species should be in the hedge with no more than 50% of any one. Hawthorn is usually significant in plantings, depending on conditions. Blackthorn, Field Maple, Hazel, Holly, and Dog Rose are also frequent. With time, of course, other native species will find their own way in.

SCREENS AND "FEDGES"

In smaller gardens the width available for a hedge might be very limited. Under these conditions there are various options, "Fedges" are a combination of fence and hedge and may be as simple as a trellis with plants growing through it. Some are available as instant hedging using, for example, ivy grown densely on trellis panels within troughs known as living green screens or ivy panels. These can be installed immediately on to hard surfaces such as paving and, provided that they are effectively watered, will give long lasting effects. Narrow screens can also be formed by bamboos provided that their roots are restricted by effective barriers to prevent them spreading out of control. Phyllostachis and Fargesia species can be excellent for this purpose.

Where larger screens are needed trees can be planted further apart and allowed to grow more freely into each other. Poplars would be a classic example of this. For more formal situations pleaching produces effective screens by weaving the branches of trees into each other. Often the tree trunks are left clear to, say six feet, leaving a line of sight beneath. Limes, Hornbeams, Beech and fruit trees are commonly treated in this way.

HEDGES FOR SPECIAL SITUATIONS.

It is usually a good idea to check the varieties of plants doing well locally in similar situations. For situations where there are salt-laden, high winds Berberis darwinii, Cotoneaster, Eleagnus, Euonymus, Fuchsia "Riccartonii", Garrya, Hippophae (Sea Buckthorn), Blackthorn, Griselinia and Tamarix may all thrive. They will need to be well staked and protected in the windiest areas.
This has been an introduction to hedging and is given in good faith but cannot be expected to cover all situation. For more complete details at a very reasonable price we recommend the Royal Horticultural Society's excellent concise guide. This costs just £4.99 from RHS at www.rhs.org.uk or 01483 211320.

CHOOSING A TREE FOR A SMALL GARDEN

Many of us have small gardens and naturally we want to make the most of them. A tree can set the atmosphere of a garden faster than almost anything else and so choosing the right one can be important. If you choose the wrong one you can spend several years being disappointed and more years waiting for a replacement tree to establish itself.

The trees you like best will be entirely a matter of taste and personal association but there are other questions which determine whether they will thrive and look right in the situation which you provide. These are questions of soil conditions, exposure, hardiness, shade, closeness to buildings and boundaries, site lines and final height. With all these factors to consider a good starting point is to see what thrives locally in other gardens and parks. If they do well in your neighbourhood they are more likely to thrive in your garden. You may find it difficult to put a name to a tree which you like. Some public parks and arboretums have labelled their trees making the task much easier for you. It is also my experience that people who enjoy their own gardens will happily share advice, so don't be afraid to ask what the tree in their garden is called and how happy they are with it. In addition there are some excellent books and below I list three which have been useful to me over many years.

The conditions in your garden.

Firstly the soil. Some trees will not thrive in acid soil, some not in thin chalky soils, some will hate wet soils and some soils which are very dry. There are many however which are tolerant of a wide range of conditions and I list a few below. You can test your soil using a test kit from a garden centre or send off a sample to an expert organisaion such as the Royal Horticultural Society. I have never bothered because I can see what does well in my neighbourhood and I know that the soil in my small garden has been cultivated for a hundred years and is a couple of feet of topsoil over clay and limestone. Digging a test hole however will give you an idea of the depth of topsoil (topsoil is the darker soil full of decayed vegetable matter which is at the surface of all natural soils), the amount of clay or rock and the dampness. You shouldn't despair if you only have a couple of feet of soil before you get down to clay or rock. Many trees thrive in this amount and the majority of roots of even large trees tend to be in this top layer.

Hardiness. Within the United Kingdom there is only a limited range of weather conditions but exposure to winds or salt from the sea can greatly effect a tree's chances of survival. Across a continent the size of North America or Europe there is a much greater range of conditions and you may need trees to thrive in the extremes. The books below would give you a good idea of trees for difficult conditions.The Hilliers Manual in particular gives excellent lists of trees and shrubs for many situations and to provide many different effects. Trees for a Small Garden (see below) gives maps of hardiness zones so that you can judge whether a tree is likely to survive.

There are several groups of trees which contain species and varieties suitable for a wide range of conditions and which are unlikely to finish more than 15-30ft high. The most useful are probably Malus (apples including crabs), Prunus (cherries and a large number of related trees), Sorbus (rowans, whitebeams etc), Crataegus (thorns) and Betula (birches). I would add Acers (maples) and Salix (willows) for more particular situations. There are few evergreens amongst these groups and so Ilex (hollies) and smaller conifers may also need consideration.Within these groups is a large selection of many of the most valuable small trees. However, since the selection is so big, you will need to be pointed in the right direction to make your choice. If you don't have the name of a particular tree you will need to either visit an arboretum or other public garden, where trees are labelled for you to judge them, or you will need to look the trees up in books or on the web. There are two outstanding books useful for judging trees (and indeed other plants as well). These are -
The Encyclopedia of Plants and Flowers published by the Royal Horticultural Society. This contains brief details of most of the most useful trees and garden plants and photos of a huge number of them. It costs around £30 but could save you from making all sorts of mistakes in choosing the wrong plants. It makes a wonderful present.

The Hillier Manual of Trees and Shrubs which covers most of the plants in these categories commonly grown in gardens. The pocket edition costs around £15.

In addition I use Trees for The Small Garden by Simon Toomer, published by Timber Press. It is around £20 or $30

PLANTING A WINDBREAK

There are many situations where creating a garden is made very difficult by strong winds. These in themselves can make it hard to establish more sensitive plants but if the winds carry salt from sea water or are particularly cold the challenge is even greater. Planting a windbreak can dramatically reduce the winds suffered by both our plants and ourselves.

The first thing to remember in establishing a windbreak is that it is better to filter the wind rather than create a solid barrier. A wall or a building might at first seem like the best way to protect an area, but solid barriers create eddies and turbulence around them which may be worse for plants and for you. We are all familiar with the strength of winds between city buildings. In a similar way walls which create immediate barriers to wind also produce strong eddies and swirls of wind around them. Plants tend to filter the wind rather than deflect them so that the strength of the wind is reduced rather than simply moved to another place. They are also less expensive and generally more attractive than walls, generally improve with time and may need less maintenance.

In planting a windbreak you will need to start with a good idea of the predominant wind in your neighborhood. For most places there is a direction from which the majority of winds arrive. For instance most of the UK is subject to predominant winds from the south west although damaging cold winds can also come from other directions. For a garden located on a cliff or headland there may be frequent strong winds from more than one direction. Whichever you suffer from you will need to know about them in advance so that the trees you plant will be in the right place. It may take years to establish the windbreak so it is definitely worth getting this right the first time.

The general principle when planting a windbreak is to establish a row of large trees with dense smaller trees and shrubs either side of it on the windward and leeward sides. These smaller trees and shrubs greatly add to the overall filtering effect. As a general rule the effectiveness of an established windbreak usually stretches on the leeward side of the break for a distance which is around 5-10 times the height of the trees, but there may be some effect up to around 25 times the height. So if your trees are 30ft high the windbreak may be effective for more than 2-300 ft.

To choose plants which will do the job in your difficult situation the first thing to do is to look at the trees and shrubs which are already thriving in your neighbourhood. You may find that there is Sycamore and this is one of the few situations in which the planting of these tough trees can be easily justified in the UK. Generally they are considered a "weed tree" as they are very invasive and support little wildlife compared with native species.They are however a traditional windbreak for hill farms and exposed settlements and can provide the same function for a garden. They will of course lose their leaves in the winter and so a large evergreen tree species should be added to the windbreak. Austrian Pines, Pinus nigra, are excellent in this situation as they are resistant to strong winds and salt and do not need good soils. For an understorey of smaller trees and shrubs you would again be well advised to find out what thrives already in your neighbourhood. Near to the sea likely evergreen candidates will be Griselinia, Arbutus, Holly, Hebes, Eucalyptus gunnii, Olearia, Berberis darwinii, Phormium and Cordyline. Many of these will not thrive in cold and exposed sites. Evergreen shrubs for colder areas might be Eleagnus, Euonymus,Mahonia, Myrica, Rhododendron, and Viburnum. Deciduous trees for both situations may include Rowans and Whitebeams, Birches , Ashes , Beeches, Alders, and Willows. Shrubs could include Fuchsia riccartonii, Rosa rugosa and Gorse.

Of course planting and establishing trees in exposed conditions is also a problem. Our natural instinct is to stake them high and tie them three or four feet above ground level. However there is a problem with this. We should think of the trunks of trees in some respects as being like the muscles of an animal's body. The more they flex and are challenged the stronger they become. Therefore if we stake a tree high and then, after several years, untie it from the stake we will often find that it has not built up sufficient strength to stand alone. Our aim should be to stake it low so that it can still flex but the rootball can't move and loosen the roots. It is sufficient here to say that the tree should either have a low stake at an angle to the tree trunk, have two low stakes joined by a crossbar or should be secured by ground anchoring. Whichever system is used the stake should not go through the rootball, the above ground ties should be loosened a little each year and the tree roots should not be allowed to dry out for a year or two at least. Ground anchoring is a specialized way of securing a tree by tieing its rootball in a non-damaging way below ground. If done correctly the rootball won't move and nothing except the tree is visible above ground. It is an ideal way of planting a tree but requires rather more skill and expense than the conventional ways using stakes.

A good windbreak will take some years to establish but within it a surprising range of delicate and sensitive plants can often survive and, in addition, we humans usually feel a good deal more comfortable as well.

LARGE TREE, SMALL GARDEN. CAN THIS EVER BE SAFE?

The question of how close to your house to plant a tree is a complicated one. After a dry summer there is usually a rush of claims to insurance companies after subsidence occurs. The problems generally happen in areas where there is clay soil as tree roots can remove the water from the clay producing shrinkage. This shrinkage may result in movement of foundations and the walls which they support. Exact information is hard to give but it is possible to give a few generalisations.

I take my information from a textbook on the subject - "Tree Roots and Buildings" by Cutler and Richardson published by Longman Scientific and Technical. They work from reported problems and give the distance from buildings within which 50% of the incidents occur. If the incidents occur close to a building for a particular species this is considered to be a less dangerous tree to plant than one which gives problems at a greater distance from the house. So Willows, Poplars, Oaks and Elms can give problems at far greater distances than birches, hollies, apples and rowans.

It may be wise to consult your insurance company before you plant a large tree. Be aware however that they are likely to give a very conservative response and that our cities would be far poorer places with many less fine trees if insurance companies were the arbiters of all tree planting.

There is another way to look at this problem. In many countries street trees are planted into prepared planting pits along the sides of roads. These are effectively large sunken plantpots which allow space for tree roots to develop without interfering with buildings, drains or other services. If you are keen to plant a large tree into a space near to walls, buildings, or services it may be possible to create a pit. For large trees you would need a pit around 6ft x 6ft and 3ft deep. This would have thick walls of blockwork or, alternatively, welded steel. You would be making an enormous container with drainage holes to prevent it turning into a sump or underground pool. Drainage holes should be protected by mesh to prevent tree roots from escaping through them and defeating the purpose of the pit. It would be essential to ensure that the container can drain properly and so it is unlikely to work if the pit is dug into clay unless you provide an efficient drainage system from the pit through the clay and away.

In order to water the tree effectively and, almost as importantly, to allow air to the roots a perforated plastic tube around 50mm in diameter should be buried within the pit and to the depth of the pit but with its inlet just above soil level. These tubes are available from tree and landscaping suppliers but can be improvised from drainage pipe if necessary.

If made well this pit should allow a tree to thrive in a limited space without danger to its surroundings.

PLANTING A TREE

The principles of tree planting are similar whatever the size of tree. The idea is to try to disturb the tree as little as possible, place it in an appropriate hole and in a situation to which it is suited. An acid loving tree should not be planted in chalky soil, nor a sensitive tree in an exposed location. Some trees need good drainage or are less tolerant of frost or sea spray. Aftercare and staking are then designed to help it settle in. Larger trees of course will need more expert handling and those in pots over about 70litres in size may need moving and planting using machinery.
To prepare for planting, a hole a little larger than the pot needs to be prepared. In heavy clay this would need to be broken up around the edges and bottom to prevent it from turning into a sump filled with water which would suffocate the tree roots. In other soils this is not necessary. Neither is it necessary to feed the tree at planting or provide rich compost as it is useful to encourage the tree's roots to search for nutrients by growing into the surrounding soil. The tree should be planted so that the ground level is close to the level of the surface of the compost in the pot.
STAKING. Most trees will need some staking to prevent the wind from rocking the tree loose. It's necessary to take into account both the size of the tree and how exposed it will be to strong winds. Tree sizes are usually measured by their girth (which is their circumference in cms at 1m above the ground) if they have a single stem or by their height and pot size. For most trees up to around 16cm girth in a normal garden situation staking is by using a single stake driven in at around 45degrees and facing into the predominant wind which is often from the south west in the United Kingdom. The stake must be driven firmly into the ground avoiding the rootball as far as possible. It will usually cross the stem of the tree about 60cm above the ground. A well cushioned adjustable tree tie is attached and it should be loosened as the tree grows. Generally it can be removed after 2 or 3 years. For larger trees double staking is used (and occasionally guying and ground anchoring for larger trees or difficult situations) which consists of using two tall vertical stakes.These would be either side of the stem and outside the tree's rootball. The stakes are joined by a cross-piece which is attached to the tree by a cushion and tree tie. For very flexible young trees it may be necessary to use a taller single stake which can be reduced in height as the tree establishes. The general principle is that trees get stronger by flexing and adapting to adverse circumstances just as the muscles of an animal do. Over-staking therefore tends to produce weaker trees in the long run.
AFTERCARE It is surprising the extent to which weeds and grasses can compete with tree roots for nutrients and water. For trees planted into lawns or meadows therefore it is important to leave a clear circle about 1m in diameter until the tree is well established.. Mulching with a mulch mat or with about 50mm of bark can help both to keep weeds down and to maintain moisture levels in the soil. It is of course essential not to let the rootball dry out for at least the first year (see below). Pruning of laterals (small side branches coming from the main stems) and of dead or diseased branches can be carried out at planting.
WATERING. It is always important to remember that a large percentage of the losses in the first year or two are caused by allowing the roots of the tree to dry out. Periods of drought are especially dangerous. However watering little and often can encourage the roots of the tree to stay near the surface instead of spreading to seek new sources of water. The spreading of the roots will also, of course, stabilize the tree long after the stakes have been removed. For these reasons it is sometimes better to water trees through tubes sunk at the time of planting which provide water to the roots a foot or two below the surface. Failing this, surface watering systems such as leaky hoses can be useful especially when combined with mulches (although there are also trees, even species such as yew native to our better drained soils, which do not thrive if the soil is damp and mulched around their roots).