Australia has many terrestrial orchids, and a number of these are very easy to grow given the right conditions. These are ground dwelling orchids and include types such as Pterostylis baptistii (pictured right) which is one of the ‘Greenhoods’, one of the most common groups of Australian terrestrial orchids.
All of these orchids have have a dormant stage, and this is during the dryer months of the year. These orchids also have a relationship with specific soil fungo from which they obtain minerals and nutrients.
The growth cycle goes as follows
Summer – Dormancy to help them survive the dry period.
Autumn – They begin to come to life as the first rains appear. This is when they begin to shoot.
Winter – Active growth period.
Spring – More growth and Flowering.
….and then back into dormancy.
Australian Terrestrial Orchids – Varieties and species
These little wonders usually flower in winter and spring, and in the lightly forested areas of the southern states the observant bushwalker can usually find a range of species . Look for the well known Greenhoods (pterostyis species) with their hooded flowers. Or on a sunny afternoon, Sun Orchids (thelymitra) which actually open and close with the heat of the sun. Or perhaps the Donkey Orchids (diuris) which are one of the easier species to grow.
Many species are dormant over the hot summer, although a few are evergreen. The dormant species are sparked into life by the rains of autumn, during summer they are dormant, but as soon as the rains come the tubers are sparked ito life. Foliage appears first and is very difficult to spot in the wild, the flower then appear, and to the untrained observer are easily missed.
How to Grow Terrestrial Orchids
The greenhoods and diuris are perhaps the easiest to grow, they seem to be a little more tolerant of less than ideal conditions and will multiply and spread through the underground tubers.
Growing conditions for Australian terrestrial orchids need to mimic the natural conditions as much as possible, semi shade (like a woodland) and certainly a well drained soil.
But remember that some species require a lot more sun to flourish.
Protection from overwatering is essential, and watch out for snails especially with new growth.
Growing Terrestrial Orchids in pots and containers
Most collectors of Australian terrestrial orchids choose to grow them in containers where they not only have control over the growing conditions but also can bring the containers into view when flowering. Container growing offers a number of advantages and few problems as well.
Australia has a wide range of terrestrial orchids, many are easy to grow and some are very difficult. Given the right conditions you should be able to grow a good range in the home garden.
- Most of these orchids are dormant during the drier months of the year, they also have interesting relationships with the soil fungi. These two condition, dryness at the right time of year, and soil fungi are ate major key factors.
- Nearly all of the terrestrial orchids have a tuber a bit like a small potato. One species is even called the Potato Orchid (Gastrodia sesamoides).
- Most are dormant over summer, which is the dry period, and are therefore fairly drought tolerant.
- They spring into life in autumn when the first rains encourage them to shoot. Some sending up leaves, some a single leaf and then the flower shoot.
- This active growing period continues through to spring and into summer when the soil begins to dry again and they go back into dormancy.
Growing medium or Potting Mix for terrestrial orchids
Many gardeners will grow these orchids in pots and selection of potting mix is most important.
An Australian Native Potting Mix with 25% added perlite suits many species.
- You can also try a more elaborate mix such as
1 part Native Potting Soil
1 part Native Leaf Mould
2 parts 2 mm Gravel
1 part Euci mulch soaked for 6 hours in water.
An added tablespoon of blood and bone.
In this mix 1 part represents a 2 litre pot full
Repotting Terrestrial Orchids
Repotting will be required every 3 years or so. This is must carried out when the orchids are dormant, usually in summer .
- This is a matter of tipping the tubers out of the post and separating them from the potting mix.
- Fill the new clean pot to around 4 cms from the top with your selected potting mix.
- Place the tubers on top , with the eyes facing upwards.
- Cover with 2 cms of potting soil.
- If you can get them, cover the whole surface of the pot with Casuarina needles.
You do not need to water in immediately as the potting mix should already be damp.
Wait for a month or so and then water. Just enough to keep the soil damp.
When the leaves begin to appear again in autumn, water normally..
Most Australian native potting mixes are suited to growing our orchids but for expert advice try joining one of the Australian Native Orchid Societies. You will find a wealth of practical experience far exceeds the advice we can give.