The following article by Les Nesbitt is taken from the Native Orchid Society of South Australia Journal, May 2019, Volume 43 No 4. The article has been slightly modified with editorial changes in black.
The majority of terrestrials will have leaves showing by month’s end. A few stragglers like South Australian Corybas and Western Australian Cyrtostylis huegelii will not appear until June so do not panic yet.
Pterostylis truncata (little dumpy) flowers this month with a large flower on a short stem. This species is given a blue tag to denote watering from January otherwise there will be no flowers under Adelaide conditions.
Tasks for May
- Move the Autumn flowering greenhoods under cover as the flowers open because they generally have tall thin stems that will bend over under the weight of rain drops on the flowers.
- Rot can be a serious problem in May. Do not overwater if there is little rain; and inspect plants closely and often. The rot can be on the leaves or below ground. Look for plants that are not thriving and give them a gentle tug to see if there are any
- Move infected plants away from healthy plants to a hospital area under cover. Water from below by standing the pot in a saucer of water. Keep the leaves dry. Good air movement and at least 5 hours sunlight a day are essential for the next 3 months.
- The fast multiplying orchids will appreciate a weak dose of liquid fertilizer once a month until spring.
- Weeding is a chore this month as weed seeds germinate after rain. Pull them out while they are small maybe even with the help of tweezers.
Inspect plants closely for virus as the symptoms show in the emerging leaves. All plants can be infected with viruses of which there are many. There is no cure for virus. Infected plants must be destroyed to prevent virus spreading to healthy plants via sap sucking insects or human activities spreading sap. Infection during the growing season does not show up in the leaves until the following year. It is difficult to eliminate virus entirely hence the need to be vigilant.
Signs of Infection
- Virused Pterostylis leaves may have light & dark green blotches or be thicker than normal and look crippled or turned up at the edges.
- Another sign to look for are pointed pimples on Caladenia and Pterostylis
- Virus is harder to spot on the narrow leaves of Diuris and Thelymitra. Healthy leaves are straight with almost parallel sides. Leaves that have kinks or are curved probably have a virus. Variegated blotching may be present in severe cases.
- If only one or two plants, in a community-pot, show symptoms they can be lifted out soon after the leaves appear and before side stolons form.
- A tool can be made from wire to do this. Bend a foot on the bottom of the wire and a loop handle on the other end.
- Push the foot into the mix alongside the infected plant, rotate the foot under the tuber and lift the plant out.
- At potting time (when tubers are dormant)
- A sieve is a great time saver during repotting but at the same time an excellent way to spread virus.
- Do not shake the sieve when tubers are present.
- Pick out the tubers as you see them and drop them into a smaller kitchen sieve sitting in an ice-cream container of water. The sand and dirt wash off and falls through leaving clean tubers behind.
- Use a jet of water to remove any remaining dirt.
- Pat the lumps of mix in the big sieve to crush them to expose any tubers.
- Shaking the sieve is the equivalent of sandpapering the tubers, a sure way to spread virus.
- If several plants are virused it is better to dump the whole pot, soil and all.
- Refuse new plants that look suspect.
ALL EFFORTS SHOULD BE MADE TO ELIMINATE VIRUS FROM AN ORCHID COLLECTION.
The following article by Les Nesbitt is taken from the Native Orchid Society of South Australia Journal, April 2019, Volume 43 No 3
Terrestrial Culture – April
The days and nights are cooling down, evaporation rates are dropping and pots take longer to dry out so decrease the watering. If in doubt wait another day before watering. Regular rain usually begins around Anzac Day. There is nothing like a good rain to make terrestrial leaves pop up almost overnight. A few early flowers are out this month – Eriochilus species and possibly Pterostylis truncata. Keep up the pest control and pull out weeds while they are still small.
Sow seed on pots around mother plants of fungus dependent orchids this month. Mix seed & fine sand together to avoid wasting precious seed. A pepper shaker helps spread the seed evenly. Water gently to wash the seed into the mulch.
April is a good month to deflask terrestrials. Seedlings need to establish & harden up before winter so get deflasking completed by the end of April. Check out flask suppliers for that special species. The next deflasking opportunity is early spring.
Deflasking Terrestrial orchids
Prepare a suitable soil mix for the orchid to be deflasked along with labels & sheoak topping. Use the same mix as for adult plants.
Select a flask with strongly growing seedlings, preferably with small tubers but plants without tubers are OK. Remove the flask lid and tip the mass of plants and agar into a fine sieve. If you are nervous remove clumps of plants from the flask with tongs. Try to minimize breakages. The junction of leaf & tuber is very weak. Over a sink or lawn, use a jet of water to wash away the agar leaving clean seedlings behind.
Fill a pot with mix to within 2 cm of the rim and tamp down. Select small clumps of seedlings and stand them around the edge of the pot. Insert a label with the appropriate info as this pot will not be repotted for 2 years. Pour a handful of mix into the centre of the pot and gently squeeze mix out around the seedlings just covering the bases but not burying the leaves. Add more mix if necessary. Tamp down the mix in the centre of the pot. Add a layer of chopped sheoak needles. Water gently to settle the mix around the seedlings.
The pot can go into the shadehouse with other terrestrial pots although it helps to keep all the seedling pots together in a sunny place with good air movement. Ensure the pot does not dry out. If kept too wet the seedlings may rot. If the seedlings establish and grow strongly they can remain in the shadehouse over winter. At any sign of rot move the pots out of the rain under cover and water by standing the pot in a saucer of water.
Next dormant season as soon as the leaves have died down, add more mix to completely fill the pot. This helps to protect the tiny seedling tubers from drying up in the heat of summer. After the second growing season the tubers should all be large enough to find easily at repotting time.
As stated last month, this is the second in the series of terrestrial culture notes for growing orchids in Adelaide.
The growing season is underway although much of the activity is underground out of sight early in the month. Repotting should be completed by now. Repotting tubers with long shoots is a tricky business requiring very gentle handling. Broken shoots and the death of some plants can result. It is better to leave them until next summer.
The weather can be hot up until equinox on about March 21st. Be aware that autumn is a time of rapid change. Day-length decreases by 2 hours in the 6 weeks from the 1st of March. Our orchids respond to the longer cooler nights faster than we do. All pots should be in their growing positions for the coming winter. Increase watering in March so that by equinox the mix is damp right through to the bottom of the pot. The first Eriochilus cucullatus flowers are usually open by the last day of March with the majority blooming in April. The buds resemble a grain of wheat when they first emerge.
Eriochilus collinus (syn Eriochilus sp Adelaide Hills, Eriochilus aff cucullatus)
Thrip can be a major problem this month. Thrips love to suck on the flowers and will cause the flowers to shrivel up in a day or two. If using a pressure pack fly spray to kill thrips, hold the can at least half a metre away or you can freeze the flowers with the propellant. Repeat the spray every few days.
Pull out any weeds that germinate while they are still small. The early Greenhoods will be showing leaves and some of the blue tag Diplodiums may be showing buds. The Greenhoods will like a weak soluble fertiliser sprayed on their new leaves as they develop.
Deflasking can be done after equinox. April is the best month to deflask terrestrials as it is cooler and more humid with enough sun to harden the leaves before the cold and damp of winter. Flasks are often the only way to get the slow multiplying terrestrial orchids. Seedlings in flask that have tiny tubers establish more successfully.
Remove the second layer of shadecloth at the end of the month or first week in April. Keep up the night time hunts for pests which get more active as the nights cool.
Autumn is a good time to build or extend a terrestrial growing area. A terrestrial house should be sealed to keep out birds and animals and have shadecloth or wire mesh sides to allow the breeze to move through. I prefer a roof of angled 50% shadecloth. Other growers use a solid roof of plastic sheeting. A solid roof means you have to water your pots by hand, which is more work. It is very important that winter sun reaches your plants so site the shadehouse away from the winter shadows of buildings, high fences and evergreen trees. Galvanised mesh benching about 750 mm high will deter slugs and snails and is a convenient height for observing the pots.
The following article by Les Nesbitt is from Journal of the Native Orchid Society of South Australia, February 2019 Volume 33 No 1. It is the first of a monthly series that Les is planning to produce for this year.
It should be noted that February in Australia is late summer and dry; and that this article has been written for Adelaide growing conditions. Many of the terrestrial orchids have been dormant.
Terrestrial Culture — February
The excitement is building with the new growing season about to commence. First leaves on the early species may show this month so start looking. Look with your eyes not your finger. Many a new shoot has been broken by that dastardly finger. Keep the blue tag pots moist. Blue tag orchids include Diplodiums, Ptst. baptistii and Corybas hispidus, all species from the East Coast of Australia.
Repotting and Watering
Finish repotting as soon as possible. Many tubers start shooting this month and are easily damaged by handling. Move all pots to their growing positions for the coming winter. For local orchids adapted to a dry January-March, commence watering in the last week of February and increase watering in March. The water will run down the side of a dry pot and out the drainage holes leaving a dry plug of mix in the middle where the tubers are. Watering three days in a row should wet the pot right through. Continue light watering weekly, so pots do not dry out completely again. Top up the cut she-oak needle layer on pots as needed. This is very important for the fungus dependent species which do not get repotted often.
Topped with she-oak cuttings
Hunting the Grubs and Slugs
Start the nightly visits to pick off the slugs, snails, earwigs and grubs. Hunts are more successful on cooler nights after rain or watering. If the new shoots get eaten off as soon as they appear you might not even see them and wonder why your orchids did not come up.
If the names on labels are starting to fade rewrite them before the name is lost. Remember to pot up any spare tubers for raffles, stalls and the tuber bank later in the year.
The cauline group of greenhoods (Diplodium) from the eastern states are the first to shoot and ideally should have blue tags and have been repotted in January with watering commencing at the end of January. There are some 38 species in this group. Some come from high altitudes in NSW/Vic and start flowering there in February. They flower in March/April/May in Adelaide.
Diplodium robustum – one of the cauline greenhoods, with both flowering and non-flowering plants
Points to note about Diplodiums:
- Flowering plants look different to non-flowering plants. Flowering plants have small pointed leaves on the flower stem. Nonflowering plants have a rosette of rounded leaves flat on the ground. Usually there are only a small percentage of flowering plants.
- They flower early in the growing season. Most flower in autumn with a few stragglers in winter. None flower in spring.
- The rosette plants multiply and are easy to grow in regular terrestrial mixes. New tubers form in Autumn.
- Diplodiums are not easy to flower in Adelaide. Flowers abort if too hot and/or too dry. Grow them in the coolest shady area there is. Keep pots shaded until late March. Local species are easier to flower as they flower in winter.
- Poor tuber development from flowering plants is common. These plants sometimes die after flowering.
- Flowering plants can be tall & slender and may need supporting with a wire cylinder. Stakes can damage the developing new tubers.
For additional information on growing terrestrial orchids click here
It’s Christmas and usually, despite Australia’s hot climate, we associate Christmas with snow and cold but we don’t tend to associate them with orchids. And yet, for Australia we do have not one but two Christmas flowering orchids in snow country, that is, on the isolated sub-Antarctic Macquarie Island, an island where “[r]ain and snow are frequent, with only a few days each year with no precipitation”. Admittedly at this time of the year, being summer it is warmer with an average temperature of 7.9degrees Celsius.
The first species was only discovered in 1978 and not recognised as an unique species until 1993 when it was named Corybas dienemus (syn. Nematoceras diemenum). Previously it had been linked with Corybas macranthus.
The second orchid species is Corybas sulcatus (syn. Nematoceras sulcatum) and this species, possibly the world’s rarest orchid, has gone travelling. Staff from the Royal Tasmanian Botanical Gardens have manage to collect and amazingly propagate the seed. Amazingly because orchids, particularly the terrestrial orchids, are difficult to grow. It is now flowering, this Christmas season, but under very carefully controlled conditions in Hobart.
Click here and here to see images and read about this amazing journey.
So Christmas, orchids and snow do go together in Australia, albeit in the far flung island of the south.
Corybas sulcatus (Grooved helmet-orchid) is one of two endemic orchids which occur on Macquarie Island (Photo: Royal Tasmanian Botanical Gardens) Image Source
https://en.wikipedia.org/wiki/Nematoceras_dienemum accessed 23 December 2017
http://www.antarctica.gov.au/living-and-working/stations/macquarie-island/location/climate-weather-tides accessed 23 December 2017
http://www.antarctica.gov.au/news/2017/sub-antarctic-orchid-shows-true-colours-far-from-home accessed 23 December 2017
Steve Howard’s October Australian Epiphytes and Terrestrials Orchids Cultural Notes for Adelaide’s conditions.
- October sees many native epiphytes finish flowering and shortly it will be the best time for potting on and division as new growths are due shortly. The earlier you start, the more time the orchid has a chance to initiate new growth and mature it in time for next years flowering.
- Remove spent flowers as leaving them on the plant in wet and humid conditions leads to rot caused by botryitis.
- Be aware that aphids are in big numbers now and will cause grief to flowers and new growths.
- Malathion at 1 ml/ litre of water will knock them out.
- Repeat fortnightly for 6 weeks to break the breeding cycle.
- Apply lime to plants grown in bark to counteract acidity.
- Most terrestrials nearing completion of the season.
- Start drying off once leaves start yellowing. Keep water up to those staying green.
- Additional shade helps now as suns intensity increases
Annual NOSSA Spring Show
Steve Howard’s September Australian Epiphytes and Terrestrials Orchids Cultural Notes for Adelaide’s conditions.
Mounts daily. Generally moistening roots only.
Pots weekly. Small pots twice weekly depending on weather.
Pots can dry out faster on warmer days so keep a watch on conditions. Note some terrestrials will commence summer dormancy towards the end of the month. Those that do show signs can have water reduced somewhat.
Weak organics like Seasol and Powerfeed applied in low doses can benefit colony type greenhoods.
Low nitrogen always best for native epiphytes. Top up epiphyte pots with dolomite lime and a dash of blood and bone. Seasol a useful additive now as new seasons root start.
Pests and Disease
Botrytis will rot new buds in cold damp weather as fast as it attacks new growths from now. Aphids will increase sharply this month and favour new growth and spikes. Pyrethrum sprays eco friendly and work well, so does a hose but dry spike straight after.
Some terrestrials will rot this month if conditions have been too wet or stagnant over winter. Note this for next season and add more drainage if this has been an issue.
Keep flowering plants under cover to enjoy as can be rather wet and cold as well sunny and warm this month. Start repotting and division once flowering finished to give plants longest possible time to establish over new growing season.
Time to get busy and take note of the jobs of potting and division to be done. Sept and October are the best months to work on the collection before the hot weather sets in.
Do you have small slugs and snails in your pots? Get a cheap coffee grinder and grind up your snail pellets. Sprinkle in the pot and water them in. Bite size for micro slugs and the baits get right into where they hide.
[Terrestrials are not repotted until summer – Steve will have more on that later]
Steve Howard writes cultural notes for Adelaide conditions. These are his notes for August; for both epiphytes and terrestrials.
Pots weekly. Small pots twice weekly depending on weather. Drier conditions for hot cold types. Terrestrial pots can dry out faster on warmer days so keep a watch on conditions.
Epiphytes: Recommending feeding towards months end as days lengthen. Many plants in strong spike growth and flowering now.
Terrestrials generally don’t need to be fed although weak organics like Seasol and Powerfeed applied in low doses can benefit colony type greenhoods.
PESTS AND DISEASES
Epiphytes: Botrytis will rot new buds in cold damp weather as fast as it attacks new growths from now. Aphids will increase sharply this month and favour new growth and spikes. Pyrethrum sprays eco friendly and work well, so does a hose but dry spike straight after.
Some terrestrials will rot this month if conditions have been too wet or stagnant over winter. Note this for next season and add more drainage if this has been an issue.
Epiphytes: Keep flowering plants under cover to enjoy. Soon will be the time to start thinking about re-potting and division as spring nears.
Keep flowering terrestrials out of strong winds and heavy rains as flower stems on some varieties are quite weak when grown in cultivation
Later August will produce some warmer drying days as spring nears. Ensure small pots and plants don’t dry out at this time. Good time to check out seedling lists and prepare orders to ensure your plants arrive at the commencement of a new growing season.
Steve Howard regularly writes orchid cultural notes for various orchid clubs in South Australia. His notes are tailored specifically conditions in Adelaide. The following are his notes for both epiphytes and terrestrials for the month of July.
- Water mounted native epiphytes daily; pots weekly and small pots twice weekly depending on the weather. Hot cold types require drier conditions. Generally none to once monthly for me.
- Colder weather slows down their metabolism in winter. Foliar feeding is beneficial.
- Keep water out of new growths to avoid rot. Clones prone to this need to be moved under hard roof cover to keep drier.
- Check under leaves for scale.
Annual NOSSA Spring Show
- Weed pots as the weeds appear and ensure that they don’t get too wet.
- Remove rotted growths.
- Start baiting for slugs and snails as spikes emerge from protective sheaths.
- Provide hard cover during wet weather to stop botrytis spotting and rotting out spikes.
The following article by Les Nesbitt was published in May 2017 Native Orchid Society of South Australia Journal Volume 41 No 4. The article relates to Australian Native Orchids.
Suggested potting mixes for potted native terrestrial orchids have changed greatly over the years as some ingredients such as peat moss have become too expensive or difficult to obtain. Basic requirements are that the mix should be free draining yet retain moisture and should have an organic component that breaks down slowly and does not go mushy in winter. Most species are not too fussy and will grow in a variety of mixes.
Those tubers that desiccate in summer do better in a heavy mix that contains clay. Examples are Diurus behrii, D. punctata and Pterostylis nutans.
Tubers that rot easily in wet soil in Spring prefer an open coarse sandy mix. An example is Thelymitra antennifera.
A dry mix containing a higher proportion of sand is usually recommended for Caladenia and Glossodia species grown in pots. In contrast these orchids grow in clay soil on my property in the Adelaide Hills but there excess water can run off. In pots, excess water has to drain through the potting mix.
An organic component is vital to feed orchid fungi.
Some Basic Ingredients:
- Washed sand with rounded particles. (Not sharp sand as this sets hard in summer.)
- Soil (sandy loam, clay based loam, mountain soil)
- Native seedling mix (Bark based – sieve to remove splinters)
- Native potting mix (can be sieve* to remove larger particles)
- Chopped and sieved* gum leaves
- Perlite or isolite (but will make tubers harder to identify at repotting time)
- Composted leaf mould & buzzer chips (but needs to be gathered now for use next summer)
- Cauarina (She-oak) needles chopped for surface mulch
Some Suggested Potting Mixes
- ANOS-Vic dry mix – 2 parts coarse sand, 1 part coastal sandy loam, 1 part composted buzzer chips, 1 part leaf mould
- 100% native potting mix. (Works for drought resistant tubers, viz. Pterostylis curta & P. pedunculata)
- Native potting mix (sieved*) and isolite
- Native potting mix and sand
- Les Nesbitt’s current mix of 50% sand, 20% hills soil, 25% seedling potting mix (sieved), and 5% chopped & sieved* string bark gum leaves.
- Dry mix, 50% coarse sand, 25% perlite & 25% native potting mix
- Heavy mix, 50% clay soil, 30% sand and 20% organic matter
* Use a 5mm sieve
Thelymitra in cultivation