Orchid Culture

Course CodeBHT232
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Horticulture College -Distance Learning Plant Course

  • Learn to grow orchids
  • Learn to identify orchids
  • Work with orchids

Study this course and move closer toward being an orchid expert.

 

Lesson Structure

There are 8 lessons in this course:

  1. Introduction
    • Introduction to Orchid Species
    • Plant Names and the System for Naming Orchids
    • Orchid sub families and tribes
    • Plant Name Pronunciation
    • Orchid Plant structure.
    • Resources
    • Terminology
  2. Culture
    • Overview of Growing Orchids
    • Guidelines; temperature, light, humidity, ventilation, watering, feeding, potting mixes
    • Growing Cattleyas
    • Substrates for Geophytes and Epiphytes
    • Understanding Soils; texture, pH, nutrient availability, fertility,
    • Mycorrhyza and Orchids
    • Propagating and Potting Media
    • Nutrients and Nutrition
    • Plant Health; orchid pests, orchid diseases, other problems
    • Pruning Orchids
    • Watering Orchids
  3. Propagation
    • Sexual vs. asexual propagation
    • Asexual Propagating sympodial Orchids
    • Asexual Propagation of Monopodial Epiphytes
    • Aerial Offset Propagation (Keikis)
    • Propagating Orchids by Seed
    • Hybrid Seed Production
    • Harvesting Orchid Seed
    • Flasking Method of Seed Sowing
    • Tissue (Meristem) Culture of Orchids
    • Propagation Equipment; greenhouses, hotbeds, cold frames, mist systems, furo light boxes, etc
  4. Cymbidiums And Dendrobiums.
    • Cymbidium culture
    • Dendrobium Types -soft cane, hard cane, black haired
    • Dendrobium Culture
    • Dendrobium species
  5. Cattleyas, Vandas And Other Commonly Grown Orchids.
    • Cattleya varieties and culture
    • Vandas; main species and culture
    • Odontoglossum
    • Oncidium -types (climbing and spreading), culture
    • Paphiopedalum (Slipper Orchids)
    • Phalaenopsis (Moth Orchids)
    • Pleione (Indian Crocus)
    • Crucifix Orchids (Epidendrum)
  6. Australian Native Orchids.
    • Endemic, naturalised and indigenous plantsProblem Based Learning Project, with the following Learning Ourtcomes:
    • Determine which species of orchids are most commonly sold in your locality.
    • Determine orchid varieties which are being grown in your locality
    • Determine any orchid genera suited to growing in a warm climate.
  7. Growing Orchids: Commercial and general uses
    • Cut Flower Production
    • Basket Plants
    • Epiphytes
    • Review of Orchid Genera for Cut Flower Production
    • Environmental Requirements for many significant orchid genera
    • Vanilla Bean Culture and Production
    • Greenhouse Management for Orchids
  8. Harvest and Special Project On One Group Of Orchids.
    • Crop Scheduling; Writing a schedule for production of an Orchid Crop
    • Harvest and Post Harvest of Selected Orchid Cut Flowers; bud opening, transport, storing flowers, etc
    • Cattleya, Cymbidium, Dendrobium

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.

Aims

  • Understand the system of plant classification and naming
  • Explain appropriate way to grow a range of different orchid species.
  • Describe common methods of Orchid Propagation
  • Understand the basics of the structure, taxonomy and culture of Cymbidiums and Dendrobiums
  • Describe the identification and culture of some of the more commonly grown orchids apart from Dendrobiums and Cattleyas
  • Describe the identification and culture of some of orchids native to your locality or region.
  • Describe a range of alternative ways in which to grow orchids
  • Research commercial orchid growing

What You Will Do

  • Compile a resource file or organisations and information sources relevant to orchids.
  • Obtain and orchid flower; draw and label this flower.
  • Review 56 different orchid species in detail.
  • Obtain soil from two different areas (two different types of soils). Using the tests in the Lesson notes, do the following, name each of these soils and test the drainage of each soil.
  • Obtain (or make up) a potting mix which you consider appropriate for growing orchids.
  • Visit a nursery or garden growing orchids. Notice how and where these plants are growing.
  • Determine which plants are healthiest and assess the conditions in which they are growing.
  • Obtain enough plant material to propagate four different orchids. Propagate these orchids vegetatively.
  • Visit a nursery, or some other place which sells a wide range of different types of pots.
  • Consider the properties of the pots you see for sale and their suitability for growing orchids in. Note down the prices of each.
  • Investigate further into tissue culture processes specific to Orchids beyond the notes offered in the course.
  • Determine which species of orchids are most commonly sold in your locality.
  • Carry out research and look through any references you have and determine any orchid genera (not yet covered in this course), which are suited to growing in a tropical or sub-tropical climate.
  • Visit (virtual or real) a plant nursery which sells a range of native orchids. List differentat orchid varieties which are being grown in your locality.
  • Visit a florist shop. Notice what orchids are being sold; how they are presented for sale, how they are stored etc
  • Evaluate the cultural practices observed (or investigated) in the different enterprises which you considered in your set task.

Tips for Growing Orchids

Temperature
There are generally three temperature grouping:
1. Those grown in a hot house where temperatures range from 18 - 32°C eg. Phalaenopsis species
2. The temperate greenhouse 15-30°C.eg. Cattleya orchids
3. The cool house 12-24°C. eg. Odontoglossum species.
The difference between day and night temperatures should be at least 9°C in all three houses.

Light
Again orchids can be generally placed into three groups those that like full shade, full sun and an intermediate group which is the bulk of orchids. It may be necessary to provide temporary shade in summer with nets, mesh or white washing the glass.

Humidity
Humidity should never drop below 50%. In summer when the temperature rises the humidity will automatically drop. Large glass houses have a cooling system but in the home glass house you can keep the paths wet and place receptacles filled with water in the hot house.

Ventilation
Proper air circulation will prevent many fungal and bacterial diseases and would be one of the most important factors in growing healthy orchids. Small fans are used in many hot houses, sophisticated ventilation systems are used by larger hot houses. Excess light may cause leaf-burn in some orchids eg. Cattleya. It may be possible to create a small breeze to offset the heat built up in the leaves or provide shading.

Watering
Watering depends very much on the orchid species being grown and particularly on the time and duration of their rest period. Orchids on rafts generally need to be lightly watered several times a day during the growing season. Potted orchids may only need watering every 4-5 days. Young plants will need more frequent watering. It is best in all cases to water early in the morning so that any standing water can disappear by evening. Over-watering of pot cultured orchids, stops air getting to the roots keeping them in a sodden condition.

Poor air circulation prevents drying out of epiphytes on wooden or bark slabs and potted orchids and occurs in poorly ventilated glasshouses. On the other hand it is important not to under water. It is often better to water lightly two to three times at half-hour intervals rather than one long watering when most of the water runs off the slabs and pots.

Feeding
Orchid experts often conflict with each other on feeding recommendations. One grower will say to feed regularly and another very rarely. Different orchids do of course have different feeding requirements. If a plant looks weak and is putting on very little growth, it will usually benefit from a feed.

Most orchids are generally not heavy feeders, and too much nutrient can burn the roots. They do respond to feeding though. Slow release or mild fertilisers such as osmocote, nutricote, maxicrop or a specially designed orchid food are ideal. A weak solution of liquid fertiliser such as Aquasol or Phostrogen applied weekly during the growing season is often beneficial. When you take an outdoor orchid plant inside fertilize it.


Orchids do not need large amounts of fertiliser as they are slow growing plants and nutrient deficiencies seldom occur. But it is necessary to apply frequent nitrogenous fertilisers not so much to feed the orchid but to feed the fungi that decompose the bark in the potting mix and the bark slab. If the old leaves appear yellow and fall off prematurely it’s an indication of nitrogen deficiency. From late spring to early winter many growers use an equally balanced fertiliser 18-18-18 applied lightly once a week and 30-10-10 during the growing season.

Salting up is a problem that can occur when the pot or slab has not been flushed out with watering between fertiliser applications and results in a build up of fertiliser salts. If this happens the roots become scorched, will stop growing and the root tips may turn black.

Potting Mixes
In nature orchids grow in two different ways, geophytes or terrestrial orchids which grow in the ground and epiphytes which grow on trees. Geophytes are generally grown in a pot of bark and charcoal, epiphytes are generally grown on a bark slab or cork board. Whatever the orchid is grown in, whether it is a pot or a slab, it is called the substrate. The substrate needs to drain freely allowing the roots to almost dry out and air to circulate around the roots.

 
ORCHID TAXONOMY
 

Orchids belong to the Orchidaceae family, one of the largest flowering plant families, with 735 genera and 17,000 species.  They are perennial, herbaceous plants, which are normally terrestrial in temperate climates, or epiphytes in tropical climates.  Occasionally they are saprophytic (ie. living on dead organic material).

The flowers are normally hermaphroditic (ie. carry both male and female parts), with a perianth of 6 segments in 2 whorls - 3 in an outer whorl, 3 in an inner whorl.  Flower colour, size and shape vary greatly.  Normally there is 1 stamen to a flower (rarely 2 or 3).  The ovary is inferior, and the pistil is made up of 3 united carpels.  The ovary is 1 3 celled; fruit is a dehiscent capsule.  The seed is produced in large numbers, and is small and dust like.

The subdivision of families into sub families has been difficult with this family.  The following classification by Willis divides orchids into 3 subfamilies and 6 tribes:

Subfamily Apostasioidae
Flowers more or less actinomorphic (regular   divides into equal halves in two planes), labellum shallow, stamens 2 or 3.

Tribe Apostasieae
eg. Genus - Apostasia

Subfamily  Cypripedioideae
Flower zygomorphic (divides into equal halves in one plane only), labellum deeply saccate, 2 stamens, staminode (ie. sterile stamen) usually shield like.

Tribe Cypreipedieae
eg. Genera - Daphiopedilum and Cypripedium.


Subfamily Orchidoideae
Flowers zygomorphic, only 1 stamen, no staminode.

Tribe Orchideae
Viscidium (disc at base of caudicle) present, base of anther firmly attatched to column. eg. Genera - Orchis, Platanthera, Ophrys and Dactylorhiza.

Tribe Neottieae
Viscidium present, anther deciduous, apex lightly attached to column. eg. Genera - Listera, Spiranthes, Neottia and Epipactis

Tribe Epidendreae
Viscidium absent or poorly developed, anther deciduous attached by apex. eg. Genera - Dendrobium, Vanilla, Cattleya and Epidendrum.

Tribe Vandeae
Viscidium present, anther deciduous, attatched by apex; eg. Genera - Vanda, Oncidium, Angraecum and Odontoglossum.(Reference: 100 Plant Families by Hickey and King Cambridge University Press)



 
 
 
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