Tag: Culture Notes for Terrestrial Orchids

Terrestrial Culture – December & January

The following two articles are from the December 2019 NOSSA Journal. Written by Les Nesbitt, they cover the months of December and January.

Terrestrial Culture – December

A few late orchids such as Diuris drummondii may still have green leaves and flowers so will need watering every couple of days. Most terrestrials will have died down by now on the Adelaide Plain. Watering consists of a quick squirt with the hose once a week to moisten the top 1 cm to prevent tubers shrivelling. A small terrestrial collection of pots can be moved to a cooler place out of direct sun under a bench or to the south side of the house. A large collection must stay on the benches so extra shadecloth is added for the summer.

Repotting is in full swing now. Keep a stock of the required materials on hand including sand, soil, native potting mix, clay, blood & bone, chopped sheoak needles, smashed and sieved gum leaves pots labels, shadecloth squares for crocking, pencils to write on plastic, sieve and bowl, watering can & shadehouse benching. A system for washing and sterilizing pots before reuse is essential to control disease and virus.

Pots dry out quickly in hot windy weather. Water a day or two before repotting so that the potting mix is just moist. If too dry dust will be a problem and tubers can be damaged by hard lumps of mix. Too wet and the mix sticks to the tubers and clogs the sieve. The ideal is a mix that is easy to work when separating wet pots take tubers from mix. It helps to move some pots under cover in case of rain. Wet pots take several days to dry out which can hold up repotting. Alternatively, a sheet of plastic over the pots when rain is forecast will shed the water but remember to weigh it down with bricks or it will blow away.

Pick out the tubers and put them in a kitchen sieve sitting in a container of water. Use a jet of water to wash the tubers clean and spread them on a towel to dry. Discard any tubers that are soft or have turned black. If the tubers are healthy, firm and a pale colour the mix can be reused. Colony type tubers should have at least doubled in number since last year. Add half fresh mix to the old mix and add a big pinch of blood & bone fertilizer. Should the old mix be dark in colour, or the tubers not be healthy looking then throw out the old mix and pot up in new mix.

Select the pot size, place a shadecloth square in the pot to retain the mix when it dries out. Fill the pot with mix to about 2cm from the top. Select the largest tubers for a show pot and push them into the mix with the shoot on top. The small tubers can be potted in another pot to grow bigger next year. Cover the tubers with more mix and almost fill the pot. Firm the mix down with your hand or use the bottom of an empty pot. Cover the surface with chopped sheoak needles. Write out a label with the name of the orchid and the provenance,
if known. On the back of the label note the number of tubers and the date planted. Water the pot gently so as to not disturb the needles. This helps settle the soil around the tubers and makes subsequent watering easier. Put the finished pots back in the shadehouse to await the next growing season.

Send off your tuber bank order before Christmas or you might miss out on your choices. The tuber bank is a great way to increase your terrestrial collection.*

*Tubers are sold only to financial members

Terrestrial Culture – January

Start watering the blue tag pots in January. Pots of orchids from the East Coast of Australia where it rains in Summer are given a blue tag as the culture is different compared to local terrestrial orchids. This early shooting group includes most cauline greenhoods, Pterostylis baptistii and Corybas hispidus. Local South Australian tubers can be kept completely dry until at least mid-February if pots are shaded.

When your tuber bank order arrives, pot up the tubers straight away. Plant each species in a separate 125mm or 150mm pot. Don’t forget to record the provenance name (if known) on the label and in your recording system. The
provenance is the location of the original collection. Provenance is important because in 10 years the orchid will possibly be extinct in that area as suburbia expands or weeds take over the habitat.

Summer watering is important. Too little and tubers may dry up. Too much and they may rot or come up early before the heat of summer is over when they will be attacked by thrip and aphids. A light sprinkle on top of the pots once a
week works OK.

Try to finish repotting this month. If left until February there is more chance of breaking off the new shoots which can be well developed by late February.

Terrestrial Culture – November

Though a bit behind time, but for completeness, Les Nesbitt’s culture notes for November 2019 from the November 2019 NOSSA Journal are reproduced below.

After the first week in November, pots dry quickly and it is hard to keep pots moist. Water green leaves, let the others dry off as plants die down. Late species in flower this month are Diuris drummondii, rufa group Pterosylis & Microtis. Seed pods ripen quickly now, so check every couple of days.

Repotting can start at month’s end although Dec – Jan is the ideal time if there are only a few pots needing to be done. Repot orchids with large tubers first as they are more prone to rotting if there is prolonged hot wet weather this month. We usually get at least one thunderstorm before Xmas. Until the old tuber has completely dried up it can go mouldy and infect the new tuber alongside. This especially applies to the slow multipliers such as Diuris and Thelymitra that have large tubers.

Gather potting mix materials and pots ready for the summer activities as this growing season comes to an end.

TYPES OF POTTING MIXES

Terrestrial growers all have their favourite mix that works for them. Some recipes are:

~ Half premium native potting mix and half sand.
~ Sand, buzzer chips, mountain soil (see ANOS cultivation booklet).
~ 50% sand, 20% Hills soil, 30% organic matter ( seed & cutting mix, native potting mix, smashed gum leaves).
~ Eco terrestrial mix (fine composted pine bark) and perlite.

Some species require adjustments to the mix for optiumum results. Caladenia like more sand, Diuris & Pt nutans 30% clay, Acianthus pusillus more organic matter. The mix must be free draining in Winter yet retain moisture in Autumn and Spring. Most growers reuse some of the old mix, (up to 50%) to which new ingredients are added at repotting time. The reason for this is to carry over any fungus in the old mix. Add a little blood & bone fertilizer and native slow release pellets. Most of the orchids in cultivation prefer a slightly acid soil mix.

Locate a source of Casuarina trees in your area and collect the fallen needles. These trees grow all over Adelaide. Chop the needles into lengths of 1 – 5 cms and store in a dry place.

POTS

The ideal size pots for terrestrials seem to be 125mm & 150mm standard pots that are about 150mm deep. Smaller diameter pots dry out quickly and it is difficult to keep the mix moist in Spring. Shallow clay pans can be used for specimen show pots.

November is a good month to flask seed of Diuris for planting out next autumn. Terrestrial seed can be sown in flasks at any time of year but some months are better than others to match tuber development in flask with optimal deflasking in April.

Monthly Terrestrial Orchid Culture – August

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.

Monthly Terrestrial Orchid Culture – July

Continuing Les Nesbitt’s articles from the NOSSA Journal, this month’s (Vol 43 No 6 July 2019) is a relaxing time.

Midwinter is cold and cloudy most days. July is often the wettest month as well. A good time to sit by the heater and read orchid books or search the internet as you plan future activities. Tidy up your records and draw up a wanted list of terrestrials to purchase or swap. Activity in the lab continues with seed sowing and replating. Deflasking should wait until spring as tiny seedlings rot away if planted out in winter. Pots showing any signs of rot should be moved out of the
rain to dry off.

Not a lot to do in the orchid house except observe your orchids and watch for pests that are always looking for a feed. Growth will be slow. Give plants as much sunlight as possible. The very first seedling leaves may appear this month around mother plants. Give yourself a pat on the back if you see any seedlings. More may show in August & September.

Corybas flower this month and do not mind being cold and wet. Corybas flowers will shrivel up if the surrounding air is dry. Mist them daily or place a clear cover over the pot & the flowers will last for weeks. A tall plastic sleeve around the pot or an upturned glass bowl can be used.

Orchid clubs hold their Winter shows this month. Check them out for additions to your collection.

2017 October Cultural Notes

Steve Howard’s October Australian Epiphytes and Terrestrials Orchids Cultural Notes for Adelaide’s conditions.

Epiphytes

  • 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.

Terrestrials

  • 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

Epiphytes in flower (1)
Annual NOSSA Spring Show

CULTURE OF FAST MULTIPLYING (FM) TERRESTRIAL ORCHIDS

Recently, NOSSA updated the Terrestrial Culture Fact Sheet.  Instead of one sheet, it was decided to split it into three – Culture of Fast Multiplying Terrestrials, Culture of Slow Multiplying Terrestrials and Culture of Fungi Dependent Terrestrials.  Though much of the growing information is similar, there are some significant differences of which growers need to be aware.  The first of the fact sheets is Culture of Fast Multiplying Terrestrials.

FLAGBEARER SPECIES: Pterostylis curta

Pterostylis curta Labellum and column 92RL
Pterostylis curta (Blunt Greenhood) is rated rare in South Australia.  Ex situ conservation is another dimension to conservation.

Others include Chilogolottis, Corybas, Cyrtostylis, Diplodium, Microtis most Pterostylis and some Diuris. Most FMs are Autumn or Winter flowering. The exceptions are Diuris and Microtis. FM are the most common terrestrial orchids to be seen at meetings and shows. Once seedlings are established they are no longer fungi dependent.

GROWTH HABIT: FMs are the easiest terrestrial’s orchids to grow. They multiply by forming 2 – 5 tubers per plant each year. The annual growth cycle comprises 6 – 8 months as growing plants under cool (5 – 20⁰ C max, 0 – 14⁰ C min) moist conditions and 4 – 6 months as dormant tubers in hot (18 – 42⁰ C max, 12 – 30⁰ C min) dry conditions.  New tubers are produced in winter/spring. FMs are colony types, ie they multiply annually and will spread out over time if planted in the ground. Each tuber sends up a shoot to the surface in autumn and leaves grow rapidly in late autumn/early winter as temperatures fall and the rains set in. FMs mainly flower in Autumn and Winter. Diplodium & Pterostylis leaves are usually the first to appear in March followed by Diuris and Microtis in April, and Corybas in June to July. In October/November the leaves go yellow, then brown and dry as the days get longer, hotter and drier in late spring.

LIGHT/SHADE: In Adelaide, they thrive in a shadehouse of 50% shadecloth. Some species prefer heavy shade, others full sunlight but most will adapt to a wide range of light intensity. Sun loving species (Diuris & Microtis) prefer a brighter location for good growth. Corybas like the shadiest corner.  If the leaves and stems are weak and limp or if the leaf rosettes are drawn up to the light, then the shading is too dense and amount of light should be increased.

In very cold areas an unheated glasshouse may be required for frost protection although light frosts do not worry the majority of species.

AIR MOVEMENT/HUMIDITY: All species like good air movement and will not thrive in a stuffy humid atmosphere especially if temperatures are high.

WATERING: The soil should be kept moist at all times during active growth by watering gently if there is no rain.  Hand watering is especially necessary in spring as soil in pots dries out more rapidly than in the garden. Watering must be done slowly so that the matt of needles on the surface of the pot is not disturbed. Slugs and snails love these plants and must be kept under control. Raising the pots off the ground on galvanised steel benching is very effective in controlling these pests.

After the leaves have turned yellow, let the pot dry out completely to dry up the old roots and tubers otherwise they may turn into a soggy mouldy mess and rot may destroy the adjacent new tubers.

REPOTTING: They grow better if repotted annually otherwise the plants crowd together around the rim of the pot.  Repotting is normally done between November and January. The pots can be knocked out and the tubers examined without harm.  For best results repot the tubers in half fresh soil mix. A suitable soil mix is 40% loam, 50% sand and 10% organic matter with a little blood and bone fertilizer added. (They will also grow in native potting mix.) A 5 mm sieve is a useful tool for separating tubers from soil. Replant the dormant tubers with the tops 20 mm deep. Cover the soil surface with a mulch of chopped sheoak needles (20 – 50 mm lengths). This prevents soil erosion and assists with aeration under the leaves.

SUMMER CARE: Keep the pots shaded and allow the pots to dry out between light waterings until mid-February when they should be set out in their growing positions and watered a little more often. The tubers of some species will rot if kept wet during the dormant period, others will produce plants prematurely which are then attacked by pests such as thrip and red spider mite and fungal diseases in the warm weather.

FERTILIZING: FMs are very hardy and will benefit from weak applications of folia feed in the early growth stages.

OTHER CULTURE NOTES:

NB: IT IS ILLEGAL TO TAKE PLANTS (WHOLE PLANT, FLOWERS, SEEDS AND TUBERS) FROM THE WILD

 

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