Arboriculture I

Learn to care for and maintain trees. Online course includes species identification, planting, establishment, health, training, pruning, tree surgery and more. A broad foundation course for arborists, gardeners and landscapers.

Course CodeBHT106
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

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The Ideal Introduction to Tree Science

Arboriculture is the science of how trees grow and respond to their environment as well as how to nurture them.

This course covers techniques and practices used to cultivate trees so as to maintain them in good health.  This includes things like selecting appropriate trees for the conditions, planting and staking, watering and how to fertilise different trees, types of pruning, cabling and bracing damaged tree limbs,  diagnosing problems such as nutritional disorders, controlling pests and diseases, transplanting and tree removal.

Gain skills and knowledge to diagnose and treat tree disorders

This course develops your skills and understanding in diagnosis and treatment of tree disorders.

  • Learn to deal with pest, diseases, nutritional deficiences, water problems effectively.
  • Save money with correct identification of tree disorder
  • Improve your safety with correct tree surgery practices
  • Increase produce with correct pruning and training procedures

This course is essential for anyone working with trees.

Suitable for:

  • horticulturalists
  • gardeners
  • tree doctors
  • farmers
  • anyone involved with trees

8 Lessons each with a set task, 8 assignments. Course notes. Online & e-learning courses have self assessment tests.

This in-depth and comprehensive course will enable you prevent tree disorders as well diagnose and treat existing problems with trees including soil issues.

All too often trees are the forgotten giants of our garden areas. A shrub or ground cover plant is far closer to the human eye than a tree, and these plants usually get most of our attention because they are so easily seen. With trees it often seems to be "out of sight, out of mind".

Trees are in fact potentially far greater problems than shrubs. If a shrub blows over, it creates a bit of a mess and a gap in the garden bed. If a tree blows over, it can destroy half the garden, make a large hole in the roof of a house, or crush your new car. Trees, like people, can be hurt, they can get sick, and sooner or later they will die. They need to be fed and watered, and they do need "doctoring" if their life is to be extended to the fullest. Some trees, like some people, are hardier and never seem to become ill. In the same way, however, many trees have "medical" problems which no one seems to notice until it is too late!

Lesson Structure

There are 8 lessons in this course:

  1. Introduction to Arboriculture
    • Trees in the garden, Planting in the right position, Choosing the right variety, Choosing the right specimen, How to plant different types of trees, Transplanting, Tree Guards, Using a Tree Report Form
  2. Tree Biology
    • Tree growth, Photosynthesis, Respiration, Transpiration, Vernilisation, What makes foliage change colour, Tree physiology, Roots, Stems, Leaves, Bud types, How a tree grows, Vascular tissue, Cambium, Xylem, Phloem, Secondary growth, Growth rings, Heartwood, Sapwood, Compartmentalisation, Water and plant growth, Growth rate factors, Arboricultural terminology
  3. Soils In Relation to Trees
    • Fertilising, Compacted soils, Tree health and drainage, Treating soil over winter, Changed soil levels around trees, Measuring pH, Measuring soil organic content, Measuring water content, Determining fertiliser solubility, Testing affect of lime on soil, Laboratory testing of soils, Soil texture, Measuring salinity, Soil horizons, Soil Naming, Soil nutrition, Fertilisers, etc
  4. Diagnosing Tree Problems
    • Tree health disorders, Frost protection, Minimising frost and wind damage, Mulch and frost, Missletoe, Diagnosing problems, Conducting a Tree inspection
  5. Tree Surgery
    • Tree surgery-do you need it, Review of techniques, Tree surgery safety, Safety and the worker, Public safety, Safety regulations, Cavity treatments, Bracing, Cabling, Propping, Bark wounds, Tree climbing techniques, Knots, Anchoring points, etc.
  6. Pruning of Trees
    • Pruning objectives, Removing branches, Crown cleaning, Crown thinning, Crown reduction, Crown lifting, Crown renewal, Fruit tree pruning, Felling a whole tree, Felling sections of a tree, terminology.
  7. Aboriculture Equipment
    • Secateurs, Hand saws, Power tools, Safety with electricity, Engine and tool maintenance, Chain saws, Hedge trimmers, Ladders, Harnesses, Ropes, Pole belt, Spurs, etc
  8. Workplace Health and Safety
    • Duty of Care, Lifting & manual handling, Protective equipment, Handling tools and machinery, Auditing tools and equipment

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


  • Describe measures to provide healthy trees in different situations, including appropriate plant selection.
  • Explain tree biology, including morphology, anatomy and physiology, as it relates to arboriculture.
  • Develop procedures to manage soils for improved tree growth.
  • Develop procedures for managing health disorders with trees, including environmental, pest and disease problems.
  • Determine surgical techniques commonly used in arboriculture to repair damage to plants
  • Explain tree surgery techniques commonly used in arboriculture to prune growth.
  • Determine appropriate equipment for arboricultural practice.
  • Determine appropriate workplace health and safety practices for an arboricultural workplace.

What You Will Do

  • Distinguish between plants in order to identify many different trees.
  • Develop a standard tree report form, customised for surveying the condition and use of trees in your locality.
  • Explain how to treat three specified soil related problems that can effect trees.
  • Develop a twelve month program, for managing a health problem detected by you in an established tree.
  • Demonstrate bridge grafting across a bark wound.
  • Distinguish between different methods of pruning including:
    • Canopy reduction -Cleaning out -Topiary -Espaliering
  • Determine the minimum equipment required to commence business as a tree surgeon.
  • Compare different chainsaws, to determine appropriate applications for each.
  • Determine legislation which is relevant to a specific arborist in a workplace which you visit.


Understanding tree rotting is fundamental to working in arboriculture.
The process of compartmentalisation refers to how a tree naturally resists pathogen attack. It was first described in the 1970's and 1980s by an American scientist, Dr Alex Shigo. He described it as the CODIT system: compartmentalisation of decay in trees. The following is a summary of this process.

If a tree is healthy it has a natural tendency to contain the spread of wood rots as explained below:

Tree trunks and branches are made up of a series of "compartments”. The compartment walls are not actual anatomical features, but are naturally occurring boundaries within woody stems.

  • Disease/wood rots find it more difficult to break through one compartment into the next than spread within a compartment.
  • When microorganisms first attack a tree, chemicals are deposited around the wound which create a barrier to the spread of infection.
  • Some microorganisms can grow through this barrier, allowing other microorganisms to move in behind the first invaders. A snowball effect can occur, with successions of microorganisms causing further damage, and making the spread of infection difficult to contain.
  • Another "compartment" which acts to prevent the spread of decay is the "wall" of new wood and bark tissue which is produced each year. (ie. each ring you see in the cut section of wood is a barrier to infection).
  • Wood rots thus move up and down a trunk (within a tree ring) than they do further into the centre of the tree.


The Importance of Compartmentalisation to Arborists

Trees vary in their ability to compartmentalise decay. Some species do not readily form compartments, for example, Populus (poplar), Salix (willow), Brachychiton, Erythrina (coral tree) and Liriodendron (tulip tree) species.

Tree vigour, pathogen virulence and the effects of further wounding are also important factors. Tree surgery practices such as pruning, bracing and cavity treatment, which inflict further wounds on trees, may interfere with this natural process and cause the decay to spread to new wood. For this reason, cavity drilling and rod bracing of cavities are no longer standard arboriculture techniques (see next section on Tree Surgery Techniques).


Everyone likes autumn foliage; but understanding it and what it means can be important for the way you manage trees.
Deciduous plants shed their leaves in autumn or early winter, and are fully or partially devoid of foliage over the colder months of the year. This is an adaptation that allows the plant to better survive unfavourable conditions (such as extreme cold).

Prior to leaves dropping they undergo a period of senescence.

Senescence is the period during which leaf cells progressively die

Over this senescence period, tissue at the leaf base progressively dies, until finally a complete section of tissue between the leaf and the stem is dead (At this point there is nothing left to hold the leaf to the stem; so it detaches and drops to the ground.)

As senescence occurs, the amount of chlorophyll in the leaf (which gives it the normal green colour) reduces. Chlorophyll is actually only one of many pigments that generally occur in leaves; but it is usually the strongest pigment, and for that reason alone, most leaves usually appear green if the plant is healthy.

Other types of pigment chemicals commonly found in leaves include:

  • Anthocyanins – Reds, Blues and Purples
  • Carotenoids – Yellows and Oranges

Generally carotenoids also decompose rapidly in autumn, but anthocyanins break down much more slowly.

Often anthocyanins can still be at close to 100% normal levels when only 40% of normal chlorophyll and carotenoids remain. Anthocyanins are produced through chemical processes, from excess sugars in the leaves, particularly in the presence of bright light. In view of this fact; the level of anthocyanins will be stronger if the plant has been actively photosynthesising (producing sugars) over summer, combined with lots of bright autumn days (if weather is frequently overcast and dull in late summer and autumn; the production of anthocyanins is decreased).

Lower temperatures in autumn reduce the movement of sugar around the leaf, so if the weather changes from warm to cool fast, the leaf sugar remains high and anthocyanins build up; otherwise the levels of these pigments might not be so high. High levels of anthocyanins will generally result in more vivid autumn foliage colours.


Autumn colour can still vary from plant to plant within a species. Variations include:

  • the time at which colour occurs (some produce colour earlier, others later)
  • the duration of colour (some maintain good colour for longer periods)
  • the intensity of colour

Such variations can be affected by:

  • duration of seasons
  • severity of seasons
  • whether climatic changes are gradual or more abrupt
  • aspect (whether it faces north or south, east or west
  • degree of protection (whether it is exposed or protected by walls or other plants)
  • genetics
  • sex (eg. parentage of cutting/grafting material can have a significant effect in some plants


You don't become a competent arborist undertaking quickie short courses -it takes time to learn properly and embed knowledge into your mind; and it takes a properly constructed learning experience supported by capable and knowledgeable educators.

Even the best course can only take you so far though -if you have the proper foundation to build upon (through your studies); you will continue learning afterwards, through experience; and your learning is probably going to be faster, easier and more appropriate.

This is the path we strive to set you on!

What Should You Study?

Let us help you make the Best Decision for You!

  • Contact us and tell us about your passions and ambitions
  • Let us understand your situation so we can advise you properly
  • Then make a better unformed decision about what to study.


How This Course Could Help You

Knowledge of trees helps many people do their job properly including:

Tree technicians
Council workers/contractors
Those doing environmental reports
Those assessing sites or specified trees during development work
People working in re-vegetation
People working in rehabilitation of sites e.g. farms, mining areas, reafforestation etc.
Those assessing trees for public safety



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Diana Cole

B.A. (Hons), Dip. Horticulture, BTEC Dip. Garden Design, Diploma Chartered Institute of Personnel & Development, PTLLS (Preparing to Teach in the Life Long Learning Sector), P.D.C. In addition to the qualifications listed above, Diana holds City & Guild
Bob James

Horticulturalist, Agriculturalist, Environmental consultant, Businessman and Professional Writer. Over 40 years in industry, Bob has held a wide variety of senior positions in both government and private enterprise. Bob has a Dip. Animal Husb, B.App.Sc.,
John Mason

Parks Manager, Nurseryman, Landscape Designer, Garden Writer and Consultant. Over 40 years experience; working in Victoria, Queensland and the UK. He is one of the most widely published garden writers in the world.
Jacinda Cole

B.Sc., Cert.Garden Design. Landscape Designer, Operations Manager, Consultant, Garden Writer. He was operations manager for a highly reputable British Landscape firm (The Chelsea Gardener) before starting up his own landscaping firm. He spent three year
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