• Site Assessment • Site Preparation & Establishment • Design Pointers
• Clipping Theory • Clipping Tools • Clipping Technique • Simple Shapes
• Complex Shapes & Figures • Problem Solving • Growing Topiary

With thanks to Chris Crowder, Head Gardener at Levens Hall

• The theories, techiniques, tools and practical advice within these sections is aimed at covering all forms and sizes of topiary and baytrees.

Introduction
Hedges and topiary can of course be used in many ways - formal or informal, traditional or contemporary, permanent or temporary, mobile features.
Here we will look at the considerations needed for traditional topiary and hedges growing directly in the ground. Although much will also be relevant to container growing, this will be dealt with more fully elsewhere.

Firstly we must state topiary and hedges within a garden are long-term, near permanent features so their choice of planting, placing and initial establishment should not be skipped over lightly. Every garden is of course different, but thought, time and energy expended at the start will repay to great effect over the years to come.

• Site Assessment - General Design Factors
Hedges and topiary can of course be used in many ways - formal or informal, traditional or contemporary, permanent or temporary, mobile features.
Here we will look at the considerations needed for traditional topiary and hedges growing directly in the ground. Although much will also be relevant to container growing, this will be dealt with more fully elsewhere.

Firstly we must state topiary and hedges within a garden are long-term, near permanent features so their choice of planting, placing and initial establishment should not be skipped over lightly. Every garden is of course different, but thought, time and energy expended at the start will repay to great effect over the years to come.

Climate
This is certainly a factor in both the choice of plant material to train and also in individual topiary design. Unfortunately, climate is the one factor over which there is little control, short of moving house to a different area!
The micro-climate within any garden should be carefully assessed and
exploited though... small local variations and conditions can sometimes make all the difference between success and failure.
Remember, beautiful gardens and topiary can flourish anywhere - be aware of the potential pitfalls and design the garden and topiary accordingly.

Cold
One of the main criteria for plant choice will be winter hardiness... some areas never experience frost, while others may be plunged into sub zero temperatures for many months each year.
It is not just the basic thermometer reading however that has a bearing on plant growth and well being. In cold weather its effects may be eased by snow cover - a thick blanket of snow has an insulating effect for the plants beneath it and may allow some species to survive which, if uncovered, would probably perish. It is usually exposure to freezing, drying wind that is the downfall of the evergreens so popular and effective for topiary work.
In extreme climates, when ground water is frozen, they cannot replace that lost through their leaves and simply shrivel and die.
A deep Winter covering of snow is not all good news for the Topiarist
though. As the depth builds, so to does the weight stress on branches.
Breakages and collapse are often the result.
If this snow is not vital as an insulating layer then it can be knocked off before its weight gets to much to bear. But do beware as this process sometimes is as damaging and dangerous to the trees as the weight of the snow itself. Little and often is always the safest approach when it comes to snow clearing.
Where thick snow is a regular feature it is wise to plan the topiary from the start accordingly. Generally speaking, avoid wide, flat-topped forms that will collect a thick crushing layer of snow. Instead, go for narrow shapes and those with sharply pointed tops, which either shed snow naturally or will at least be better able to support its weight.
Rapid thawing and subsequent re-freezing also causes problems in some areas, but this may be due to more localised circumstances. Box in particular may be damaged when it is quickly warmed by Winter sun during the day, then quickly and deeply frozen again on clear frosty nights. Within the individual garden, there may be areas that are not exposed to the low Winter sunshine in this way and so would prove more suitable for the plants Winter welfare. In some cases, remaining deeply frozen for the whole Winter is safer.
Of course, temporary shelters may be erected around or over specimen topiary to protect them from the worst conditions. They should be designed to screen and filter the worst weather if possible, rather than be a complete barrier. A breathing netting or lath shelter is less likely to cause disease problems than an unventilated tent of plastic - and less liable to blow to pieces or away!
Unfortunately however, these temporary protection covers are usually quite unsightly and their use will depend on whether they are in full view from the house. Also worth considering is the long-term commitment required as, unless exposure in the garden changes over time from the growth of screening plantings, then any protection will have to be re-erected annually and indefinitely!

Heat
The opposite extreme from the cold conditions that we have been discussing is a very hot, possibly very sunny climate, and this is not without its own problems. Some traditional topiary subjects will not grow successfully in such conditions and although in all areas a careful choice of plants gets around this, the choice may be further limited by low rainfall. Artificial irrigation will help here, but again as topiary in the garden is a permanent and lasting fixture, if it is grown with the aid of a watering system then you are committed to providing it for life.
Very strong sunshine too is not all good news - some plants seem to suffer from sunburn! Best success will be had here again, by only using those species fully adapted to prevailing conditions. Otherwise the micro-climate within the garden might be exploited... often light, dappled shade from tree branches high above may be enough to make all the difference.
The finished shapes may here be required to do double service, not only as garden ornaments but as valuable sources of refreshing, cooling shade.
Here, shady covered walks, arbours and trained topiary summerhouses will come in to their own in the gardens design.

Wind
Wind too, causes many problems. When topiary is continually battered,
buffeted and blown about it is seldom completely satisfactory. Although to a certain extent buildings and walls will offer some shelter, these solid barriers can also create localised higher wind speed turbulence. In the long term, shelter belt plantings outside, and hedges within the garden are the answer. These screen and filter air through them and have a modifying effect on local wind speeds on the ground for many times their height. In the short term, artificial wind break materials are available and may be used until more permanent attractive living barriers - hedges - have grown.
Wind not only damages through its cooling and/or drying effect. In some seaside areas it can come laden with damaging salt spray. This is
particular devastating in its desiccating effect and may be experienced many miles inland during severe storms. Only plants tolerant of this salt spray should be attempted in such areas.
Please don¹t be put off by all this - climatic conditions in no garden are perfect, and even if they were approaching the ideal would bring their own problems. Topiary that might otherwise need only one trim each year to keep tidy would be growing away so rampantly that constant cutting would be the costly and time-consuming result!
Being aware of problems of climate and its possible effect on topiary will help you see the potential of creating and using the existing micro-climates within a plot to the best advantage. This understanding will also assist you in the choice of species to train.
So, from all these notes, don't read don't - do read do!

The Soil
The soil, although at first sight may seem to be a factor in our
considerations over which we have little control, can in fact be improved and altered to quite a large extent. It is important to stress getting it right from the start when planting hedges or specimen topiary as these are such long-term additions to the garden. Do take the time and trouble to prepare the soil well before they go in, as there will be no easy second chance! With soils, texture, fertility, pH and drainage are all important...

Texture
Texture describes the physical nature of soils and is directly related to the proportions within it of the various particle sizes. The ideal loam is a mixture of large sand particles, smaller silt and tiny clay particles. A healthy proportion of organic matter in addition gives life to the soil.
Very few areas are fortunate enough to have a perfect soil, but it can be altered and very much improved through a bit of work and the incorporation of grit or organic matter.

Sandy soils are often too free draining and nutrients are quickly leached through leaving them hungry. Here, large additions of compost, peat, manure or other bulky organic matter help produce and maintain higher water holding and fertility levels.

Soils at the other end of the spectrum with a high clay content are usually poorly drained, sticky and difficult to work. Impossibly heavy and completely waterlogged when wet, or baked rock hard when dry. Again, incorporating bulky organic matter improves them immensely, as will the addition of very coarse sharp sand or grit.

It must be emphasised again that the permanent nature of topiary within a garden allows the soil to be improved only once. It is worth it in the long run to expend the necessary time and energy getting it right. In old gardens the soil may well have been cultivated deeply and continuously for many years and perhaps no special preparation will be necessary. But in less favoured situations an attempt should be made at improving it - for example planting stations up to a metre across and possibly up to half a metre deep should be prepared for the better establishment of specimen topiary plants.
Although in time the tree¹s roots will spread and will come to rely for
their sustenance on the native, wider, unimproved substrate, it is the
assistance given in that all-important establishment period that is so crucial. It helps ensure the production of the copious, vigorous growth that is essential for building a framework from which to train forms.
Give topiary the best possible start to ensure future success.

pH
The soils pH and its fertility are inter-related factors that will affect topiary growth. pH is a measure of the acidity or the alkalinity of the soil and is recorded on a scale from 0 (extremely acid) to 14 (extremely alkaline), with 7 being neutral. Soil test kits are widely available, cheap, easy to use and quickly give a reading of the soils pH. A slightly acidic measurement of around 6.5 is often quoted as being the ideal, with anything from 6 to 8 being generally okay for a wide variety of subjects.
More extreme readings could cause problems though as certain important plant nutrients become locked and unavailable to plants.
If the soil's reaction is very alkaline, choose only those plants suitable or possibly treatment with a chelated or sequestered iron compound may help.
If the soil¹s reaction is very acid, choose only those plants suitable or treat with ground limestone or lime.

Fertility
Fertility, or the availability of nutrients to the plant, in this case
topiary, should be thought of as being a long-term need. It is therefore best to encourage a living soil, rich in organic matter which, through natural decomposition, will be the source of slowly released nutrients.
Plant growth can be supported, of course, through repeated use of artificial fertilisers, but in the topiary garden these are best seen as a supplement.
When planting, if you have any doubts as to the soils fertility then test it or have it tested. The main plant nutrients are nitrogen, phosphorous, potassium (N.P.K.), but a great many other trace elements are needed.
Ensure the soil is not deficient by adding the relevant fertiliser. Slow release organics are perhaps best for the long-term support of the topiary.
There after annual dressings, early in the season as a boost to that years growth, become more important.
An added complication relating to plant nutrition are salt levels within the soil. Too high a chemical concentration within the soil water is damaging to plants. Box topiary is particularly susceptible and other surface rooting species can have their roots burnt and killed by an over-enthusiastic dose of fertiliser concentrated too scorchingly close to the plant.

Drainage
Drainage is the last factor to deal with related to the soil, but it is
certainly not least in importance. Basically, badly drained soil spells death to topiary. Roots are living things and need air to function. Good drainage is about getting the right balance of water to air within the spaces between the soil particles. Too much water, for too long, and plant roots literally drown.
Bad drainage also leads to the spread of water-borne diseases which can be devastating - root death quickly leads to entire tree death and, because of their water-borne nature, disease speedily spreads to other victims in the garden.
If poor drainage is a problem, it must be tackled and cured before topiary or hedges are planted. A tile or perforated pipe drainage system may be necessary, perhaps leading to a soakaway... big jobs that need expert advice.
Linked with poor drainage is soil compaction. This is usually caused by foot or vehicle traffic and is much more likely to occur when the soil is wet and plastic. Soil compaction is a killer too. It causes a loss of air at the roots and stagnant anaerobic conditions there soon lead to root disease problems and death. Prevent it by careful siting of the topiary to ensure the surrounding soil does not suffer in this way. Cure, by directing traffic away or over hard pathways. Deep spiking helps repair the soil by opening it up and creating life-giving air channels down to the roots.
As with all the other considerations in this section they are not mentioned here to make topiary growing seem difficult. In fact, success will come 95% of the time by just planting, growing and training with no special treatments necessary. It is however important to have this background knowledge, so that if problems do occur, they can be identified and remedied quickly.

Light
All around, all over light on topiary is really just about the most important factor for even, tight growth. That means the bushes and trees should have available, wherever possible, the full, uninterrupted brightness of the whole sky and in all but the hottest and unceasingly burning sunshine, sunlight at all possible times.
Of course, except near the equator, where the sun daily rises to near-overhead, topiary in most regions will have their shady and sunny sides. The further towards the poles you travel the more emphasised this becomes. South facing sides of topiary in the Northern hemisphere, for example, receive more direct sun than their North sides and the effect is usually immediately obvious...
The side getting most sunlight grows thicker, tighter, closer and stronger than that in the shade.
It is worth noting too, that although some of our most popular topiary plants, for example Yew and Box, naturally and happily grow in shade within woodland. In the garden setting as clipped specimens, best results will only be had where they receive maximum light.

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