With Spring on the way, things are starting to change in the Orchid House. Here are Les Nesbitt’ notes from the August Journal 2019 Vol 43 No 7
Terrestrial Culture – August
The days are getting longer now, noticeably so after the middle of the month. When the clouds clear, the sun is stronger & higher in the sky. Temperatures increase and growth speeds up. Lots of buds are developing so there is plenty to see in the orchid house. The greenhoods are a feature with Pterostylis curta, nutans, pedunculata and their hybrids are all flowering.
Pests become more active. Look out for aphids on flower stems. Depending on the season deflasking can start after the middle of the month if a sunny and dry Spring is forecast, otherwise wait until September.
The NOSSA Spring show is only a month away. Start preparing your specimen pots for the display. Any spare pots can be sold on the trading table. There are never enough terrestrials on the trading table at the show to meet the demand.
Photograph your orchids when the flowers are at peak condition. Then hand pollinate a flower or two to get seed for the NOSSA Propagation Workshop or for sowing around mother plants next autumn. Prepare two pots of each species, one for showing and one for seed.
How to hand pollinate.
Look closely at the flower column to see the positions of the pollen and the stigmatic surface. Flowers can be self-pollinated if there is only one. Fatter pods with more viable seeds result if two plants of the same species are cross pollinated. That is transfer the pollen from one flower to a flower on another plant. Cross pollination mixes the gene pool to prevent inbreeding. Use a toothpick or a she-oak needle to touch the pollen which will stick to the wood. Wipe the pollen across the stigmatic surface of the other flower and the job is done.
If pollination is successful, the flower will collapse in a few days and the ovary will start to swell. For greenhoods the stigmatic surface is halfway up the front of the column. Remove the front of the flower and the lip so you can see what you are doing. Greenhoods have yellow pollen. For Diuris and Thelymitra the white pollen is hidden behind the sticky stigma. Caladenia have yellow pollen under flaps at the top of the column. Stroke upwards to open the flaps as would an insect backing out of the flower. The stigma is a hollow sticky depression just below the pollen. You will have to tip the flower right back to see it.
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.
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.
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.
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
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.
- 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
A common question asked is when to water terrestrials. The short answer is to keep them dry over summer but there are variations such as was previously posted about the watering regime for Chiloglottis. In the March 2017 NOSSA Journal, Les Nesbitt’s article highlights another watering variation.
Jane Higgs’ lovely pot of the red form of Pterostylis coccina in flower had a blue tag. Jane explained that a blue tag meant that watering had to commence in January for that pot and not at the end of February as is normal for most terrestrials. Start watering later and there will be no flowers. Her pots are under a solid roof. She explained that in the ANOS Vic cultural booklet (Cultivation of Australian Native Orchids) there is a list of cauline type greenhoods which she tags with blue, and includes Pterostylis decurva, aestiva, laxa, coccina, revoluta, reflexa, truncata, robusta, alata, and fischii. To this list can be added abrupta and also the rosette types ophioglossa and baptistii which shoot early.
I have trouble growing and flowering this group of Autumn flowering greenhoods. I went home and dragged out my ANOS Vic booklet and brushed up on the notes. I found several old blue labels in the shed and cut them into strips. I now have blue labels in my pots and the pots are grouped together in the shadehouse where they get afternoon shade. They were given a thorough watering but it will be too late to expect flowers this year. I find large tubers of this group rot easily in Spring and the plants go dormant earlier than other greenhoods. I will try to remember to move the pots under cover in September to let them dry off.
Having a visual reminder would certainly make it easier to know when and which pots to water. Obviously other coloured tags can be used instead of blue, so long as they stand out from the label.
I have recently been learning about propagating orchid via flasks but I have mould in some of the flasks.
There is mould in the flask with orchid seeds and also in the flask with Diuris tricolour in bulbs. The bulbs are almost ready for deflasking.
What can I do?
With a home laboratory, no matter how careful one is, mould can still contaminate the jars of agar. If mould occurs when the orchids are still in seed, then the whole jar needs to be discarded. The seeds will not survive.
With the Diuris flask, as they are almost ready for deflasking, pot them out straight away. This needs to be done within 10 days of the mould appearing. The weather (March, 2017, South Australia) is still a little too warm but if left in the flask, the plants will die. Potting them out may give them a chance of survival.
When deflasking, it is important to rinse all the agar off the bulbs before potting on as normal. Once potted, it could help to cover the pot with a cut down clear drink bottle with the lid removed. This will allow some air to circulate. Keep the pot in a shady spot.
Will it survive in the pot? Hopefully it might but at least the plants have a better chance of survival then if left in the flask where it would surely die.