Study identification, taxonomy and cultural requirements of iris plants. Grow them commercially as cut flowers or in a nursery or at home. Understand how to grow and propagate these plants.

Course Code: VHT111
Fee Code: S2
Duration (approx) Duration (approx) 100 hours
Qualification Statement of Attainment
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Become an Expert in Growing Iris

Learn to identify, grow and use Irises.

Explore a passion, start a business or improve your opportunities for working in nurseries or gardens.

Expand your horticultural expertise.


How are Iris Classified?

The iris genus can be divided into three broad groups as follows:

1. Bulbous
2. Tuberous
3. Rhizomatous

Bulbous Division

  • These plants that produce bulbs
  • These are divided into the Xiphium Group (which includes Dutch Iris) and others

Tuberous Division

  • These plants that produce tubers
  • This includes Nephalensis species

Rhizomatous Division

  • These plants that produce rhizomes
  • Divided into three sub divisions:
  • Apogon Iris (Beardless)  Includes Sibirica, Spuria, Californian, Hexagona, Lavaegata and other groups.
  • Evansia Iris (Crested)   -These are generally the earliest flowering Iris (late winter in temperate climates)
  • Pogon Iris (Bearded)  Includes dwarf bearded  group, germanica group and other bearded iris


Lesson Structure

There are 8 lessons in this course:

  1. Introduction
    • Review of the system of plant identification
    • Physiology
    • Information sources
  2. Culture
    • Planting
    • Staking
    • Mulching
    • Watering
    • Feeding
    • Pruning, etc.
  3. Propagation and Hybridisation
    • Seed
    • Division
    • Separation
    • Tissue Culture
    • Review of selected species/hybrids.
  4. Review of Major Types of Irises
    • Bearded
    • Louisiana
    • Siberian
    • Dutch
    • English Spanish
  5. Pest and Diseases
    • Review of species from contrasting environments
    • Review of various health problems
  6. Water Irises
    • Review of species
    • Irrigation
    • Irises in Hydroponics
  7. Landscaping with Irises
    • Garden Design
    • Cottage Gardens
    • Using Colour
    • Review of more Iris species
    • Flower bed design
  8. Harvest, Post Harvest, Exhibiting and Quality


  • Explain the taxonomy of Iris
  • Explain the normal cultural requirements for different types or Iris.
  • Breed and propagate Iris.
  • Describe the identification and culture of a range of commonly cultivated Iris.
  • Manage pest and disease problems on Iris
  • Manage water requirements for Iris
  • Discuss cultivation of Iris hydroponically
  • Explain the use of Irises in landscaping
  • Describe the production of Iris as a cut flower crop, in particular the harvest and post harvest.


Growing Iris Tips from our Tutors

There are over 200 species of Iris and many thousands of cultivated varieties.
  • There are species which will grow well in most temperate and sub tropical climates; and some that will grow in climates even wider than that.
  • Some will grow totally submerged in water, others will withstand extended periods of dry.
  • Some tolerate snow and frost, some will tolerate extreme heat.
  • Some like heavy shade; others grow well in full sun.

It is important to choose the appropriate type of iris for the conditions you plan to grow it in.

There is no “ideal” location for “all” irises.


  • Irises occur naturally in both sub arctic and sub tropical climates
  • Irises can be found growing naturally at very high altitudes above the snow line, and also close to sea level.
  • There are iris species that are native to deserts, and other species that are native to swamps.
  • There are species which must have very well drained and dry soil at least part of the year, and others that need soil rich in humus and saturated with water.
  • Some grow in alkaline soils, while others will die if the soil is not acidic.

If you are going to select the right iris for the right position, you need to get to know the differences between species and cultivars, and understand the factors that characterise the places you wish to grow them.

Consider the Site
 Does it have any particular problems which should be treated?

  • Hard clay soils need to be loosened up by cultivation, or by adding soil conditioners such as lime or gypsum, or by incorporating organic matter, such as well rotted manures and compost.
  • Sandy soils can sometimes dry out too easily or be low in nutrients. To overcome these problems add well rotted manures or compost, or wetting agents.
  • Check soil pH (the degree of acidity or alkalinity). Most plants prefer a slightly acid or neutral soil (pH of about 6 to 7.5). Most Iris prefer a pH that is a little more acid than this (less than 6), but will tolerate up to neutral (7). Plants that prefer a pH slightly more alkaline (eg Lavender) may not grow as well alongside iris.  Simple test kits can be readily obtained from nurseries, garden centers, etc. You can then either choose plants that like the pH of your soil/growing media, or you might alter the pH to suit the plants you wish to grow. pH can be raised by the addition of lime, or lowered by the addition of acidifying materials such as Manures, Sulphate of Ammonia, or Sulphur powder (only for small areas as it is relatively expensive).
  • Provide wind breaks or channel winds with fences or planting, to both protect tender plants and ensure good ventilation (If the garden is totally enclosed, air movement is restricted, and that can result in an increase in diseases.
  • If necessary, select plants to grow that will tolerate or even prefer periods of shade.

Many Iris Species will Respond to Better Soil

Before you plant any iris in a new garden, make sure the soil is in a condition appropriate to the species being grown.

This may involve making sure drainage, nutrition, the soil type (e.g. sandy, clayey), and the structure of the soil is suitable for the plants you wish to grow. It may involve laying drainage pipes; applying fertilisers, gypsum (to improve the structure of clay soils) or lime; or digging in manure and compost. Always thoroughly eliminate any existing weeds.

Our principal John Mason is a fellow of the Chartered Institute of Horticulture

ACS Distance Education is a member of the Australian Garden Council, Our Principal John Mason is a board member of the Australian Garden Council

Member of the Nursery and Garden Industry Association since 1993

ACS is a silver sponsor of the AIH. The principal, John Mason, is a fellow. ACS certificate students are offered a free membership for this leading professional body.Provider.

Course Contributors

The following academics were involved in the development and/or updating of this course.

Diana Cole

Dip. Horticulture, BTEC Dip. Garden Design, Permaculture Design Certificate, B.A. (Hons)-Geography, Diploma Chartered Institute of Personnel & Development
Diana has been an enthusiastic volunteer with community garden and land conservation projects sinc

Adriana Fraser (Horticulturist)

Adriana has worked in horticulture since the 1980's. She has lived what she preaches - developing large gardens and growing her own fruit, vegetables and herbs and making her own preserves.
In 1992 she formalised her training by graduating with a certif

Rosemary Davies (Horticulturist)

Rosemary trained in Horticulture at Melbourne Universities Burnley campus; studying all aspects of horticulture -vegetable and fruit production, landscaping, amenity, turf, aboriculture and the horticultural sciences.
Initially she worked with the Depart

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