Take the Guesswork Out Of Plant Selection
In order to choose appropriate plants for gardens and other landscapes it is important to have a sound knowledge of how plants are affected by the environment such as soil types, nutrients, wind, extremes of weather, altitude and latitude, weed competition, pest and diseases, and so forth. Often the reason a plant fails to thrive in a given location is because of many factors combined. It is more difficult to try and modify the environment for plants than to choose the best plant for the site in the first place.
The success of a garden is largely determined by three interconnected factors:
- The suitability of selected plants to the conditions in which they are expected to grow.
- The use of optimum plant establishment techniques.
- The garden maintenance regime.
A well-selected plant is more likely to survive establishment and be easily maintained.
Understand how to choose the right plants
This course involves far more than just reading and answering questions. Here are just some examples of other things which you might be doing:
- Visiting different gardens, nurseries and/or parks. These could include home gardens, parks, commercial or any other type of site. The choice is yours. If for some reason (e.g. disability or isolation) you are unable to physically visit gardens or other places, you may undertake a "virtual visit" using the internet; and liaise via email.
- Survey or interview industry people.
- Analyse and devise maintenance plants for different areas.
- Research the cause of an incident.
- Prepare a weed collection of either pressings, photographs or illustrations.
Lesson Structure
There are 10 lessons in this course:
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Introduction: What to plant where, Plant selection, Plant varieties, Which plant, Colourful year round foliage, Establishment (timing, soil preparation, pot plant size, planting technique), Maintenance programs, Plants that tolerate poor drainage, Coastal plantings.
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Woody plants Selecting woody plants, Trees, Deciduous and Semi deciduous trees, Evergreen trees, Flowering shrubs, Selecting flowering shrubs, Establishing woody plants, Planting procedure, Planting deciduous and bare rooted plants, Shade.
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Windbreaks, hedges and screens Purpose of windbreaks, hedges and screens, Selecting plants for screening, Establishing screens, hedges and windbreaks, Pruning an established hedge, Hedge trimmers.
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Alpine and water plants Selecting alpine plants, Establishing alpines, Rock gardens, Raised beds, Sinks and troughs, Selecting water plants, establishment and maintenance of water plants.
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Annual and herbaceous plants Advantages of annuals, Types of annuals (edging plants, groundwork plants, dot plants), Low, medium and tall annuals, Scented annuals, Colourful foliage, Bedding schemes (pure, mixed, single variety, single genus, standard garden, standard park), Annuals from seed or seedlings, Annuals in containers, Selecting & establishing herbaceous plants, Popular herbaceous plants, Supporting herbaceous plants, Maximising flower displays.
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Turf Selecting turf, Turf varieties, Lawn mixes, What to grow where, Wildflower meadows, Turf establishment, Soil preparation, Seeding, Sodding, Instant turf, Stolonizing, Sprigging, Plugging, Mowing turf, Mo0wers, Mowing guidelines, Mowing heights, Fertilizing turf.
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Maintenance Fertilizing, pH, Replacing plants, Pruning, Pruning deciduous trees & shrubs, Irrigation systems, Irrigating turf, Irrigating garden beds and container plants, Designing an irrigation system, Sprinklers, Flow rates, Micro irrigation, Avoiding watering, Humidity, Mulch, Developing a maintenance program.
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Pest and disease control Preventing pest and disease problems, Non chemical control, Chemical controls, Environmental problems, Insect pests, Viruses, Fungal diseases, Bacterial diseases.
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Weed control Chemical and non chemical control, Safety with weedicides, Alternative weed control strategies.
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Risk assessment Identifying risks, Preventative maintenance, Duty of care, Workplace safety, Illness, Protective clothing, Safety equipment, Safe5ty with tools and equipment, Safety with electricity, Tool maintenance.
Aims
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Develop knowledge of the range of applications for and selection and establishment of horticultural plants.
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Develop knowledge in the establishment and maintenance of a range of woody plants, with different modes of growth, for different situations
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Develop knowledge in selection, establishment, and maintenance of species suitable for hedges windbreaks and screens.
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Describe the cultivation of alpine and water plants.
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Describe the selection, cultivation, and maintenance of herbaceous plants.
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Explain the selection, establishment and maintenance of turf and lawns.
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Explain the maintenance and cultural requirements of herbaceous, woody, and other plants.
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Consider the different pest and disease control implications resulting from the choice of different plant varieties.
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Determine pest and disease control requirements for a new garden.
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Explain the control of weeds in a garden.
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Explain the implications upon weed management that result from selection of particular plants for use in a garden.
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Manage establishment and maintenance of plants in a way that minimizes safety risks to people working in or visiting a garden.
What Plant Should Go Where?
There are many reasons why plants do not grow well in a particular garden or in a particular place. Most of these are caused by a combination of local climate and soil conditions. Some common problems include
- Dry Conditions -on slopes or in sandy, exposed soils.
- Alkaline soils - these are soils with a pH greater than 7 (note though that most plants will grow slightly outside of their preferred range, so it is not always necessary to change pH if it is within a reasonable range. For example most acid loving plants will still grow at pH 6 even though they may optimally prefer pH5.
- Waterlogged soils - where drainage is poor, generally due to the site being in a low lying area, or because of poorly structured soils, such as heavy clays.
- Salinity - in some parts of the world, this is a problem not just in agricultural areas, but increasingly in urban fringe areas. The overuse of fertilisers combined with drip irrigation can cause localised salinity problems around the base of plants (for example). If you are in prolonged drought or extended dry conditions - take care to use organic fertilisers rather than fast release ones and if possible deep water the soil occasionally to flush down salts.
- Strong winds, poor soils and salty conditions associated with coastal areas.
- Windy areas. Wind not only blows plants over, but it also dries them out, Wind increases evapouration of water from both foliage and soil.
- Heat. Plant growth slows at high temperatures; humidity can increase (increasing the risk of fungal disease), foliage and soil can dry out much faster. There are many negative affects if the temperature gets too high.
- High humidity (some plants suffer from fungal disease in humid conditions e.g. roses).
There are two main ways to overcome such problem areas in the garden:
- Modify local conditions to better suit the plants you wish to grow e.g. irrigate in hot, dry areas, grow or build a windbreak in windy areas, improve drainage, or lower soil pH in alkaline soils. However such remedies can often be very difficult to achieve and can be time consuming, or expensive - so the following option is most probably the best (when at all possible).
- Grow plants which suit, or will cope with the conditions present in the garden. If you choose your plants carefully you are more likely to create a garden that is very rewarding in terms of its appearance, and its hardiness.
Replanting an Old Garden
When you are faced with the task of restoring an old garden, it may be a significant challenge to discover and recreate plantings as close to the original design as possible; original planting design of any garden will commonly change over time.
First, you must as far as possible determine what was previously planted, and how it was arranged. Look for any old records, such as plant lists or plans. For some gardens, these may be relatively easy to find. If the design was created by a designer of merit, the materials may be archived in a private collection or library. If the company that created the garden is still in existence, records may be available through that company. Sometimes photographs can be found in private or public records. If people who used the property along time ago are still alive, they may remember details.
If no documentary evidence is found, there are still other things that can be investigated - look for evidence of original or past plantings on the site. Some old trees or shrubs may still exist from the original plantings. Many tree species can survive for hundreds of years, and even a dead or almost dead tree can sometimes be identified as part of the original design.
Look for plants that have invaded parts of the garden (or park) or nearby properties that match the time of the original garden (e.g. if ivy has become invasive in a neighbouring property, it may have been part of the original planting of the garden and may have spread to the neighbour’s property.
Identify indicators of types of planting in the original garden; for example: the remains of a pergola (even just foundations), may be an indicator of a climber in that location; mounded rows of earth may indicate a former area for row crops (e.g. vegetables), and a raised bed containing better quality soil than the natural earth may indicate an area of more intensive cultivation: perhaps annuals or perennials. In some gardens aerial surveys have located planting holes left after trees were removed (some up to 400 years old!).
Research local records: period nursery catalogues can indicate the varieties of plants commonly used at the time of the garden’s establishment. Photographs, plans or even articles in publications of the period can indicate likely planting combinations and styles.
Critical aspects of garden planting restoration are to:
- Determine what existing plants and features to retain.
- What new plants to introduce.
To make these decisions, you need to conduct a plant survey and consider:
- What plants are growing on the site.
- Which of the current plants were in the original design and whether any were not intended to be in the garden i.e. planted later or self-sown from neighbouring properties.
- What did the original planting design intend and is that intent still valid and viable.
Current Plantings
Existing plantings may or may not need replacing. You should consider:
- Are plants healthy?
- Are they safe? (Trees may be original, but may be dropping branches, causing damage to structures or have some other negative attributes).
- Are they in character?
- Are they creating other problems (e.g. harbouring pests or disease, costly to maintain, invasive, etc.
Other Considerations
- If possible a photo should be taken of each plant.
- Maps of the property should be used to locate and record plant features (in some cases GPS grid reference may be recorded using digital technology).
- Each plant should be identified by experts this enables them to identify which plants, trees or heritage vegetables need to be propagated for a renewal program. This may also uncover rare species that which may have been bred by plant collectors or gathered by plant hunters on expeditions – some of these species may be hundreds of years old.
- Working kitchen gardens should also be part of the survey to provide information on rare and threatened heritage varieties of vegetables and fruits which may be found in the garden – it may be also possible to collect seeds or cuttings for propagation purposes if plants are still in existence and require renewal.
- It may take a year to audit and map a site – this is to ensure that all species are included i.e. bulbs, herbaceous perennials that may be dormant at the initial time of audit.
HOW THIS COURSE MAY BENEFIT YOU
- Expand the number of plants you can choose from when selecting cultivars for landscaping
- Better understand what the plant might grow into
- Better understand the risks associated with planting a poor selection in an inappropriate location.
- Become a better designer, consultant, nurseryman or horticulturist
- Improve your career and business opportunities
- Save money and time -no traveling to classes
- Determine when, where and how long your study sessions are, for yourself
- Improve your career and business opportunities
- Make valuable connections with people and organisations in the horticultural and landscaping industries.
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