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 – June

It’s June and the the orchids tubers are on the move. And yes there are some tasks for this month but as can be seen by Les Nesbitt’s notes in the June 2019 NOSSA Journal (Volume 43 N0 5) there is not a lot to do.

Diplodium robustum  (syn Pterostylis robusta) – one of the cauline greenhoods


June is cold, often with frosty mornings and sunny days. Terrestrials can take -20C but any colder results in permanent damage. If you live in the country, you may need a solid roof for frost protection. Frosts are rare these days in Adelaide. I have black rubbish bins full of water under the benching in my glasshouse to moderate the temperature. The bins absorb heat in the daytime and radiate it out at night. If it is not frosty it will be cold wet and cloudy. Growth will be slow and there are few flowers out. There is not a lot to do in the terrestrial house.

Pterostylis robusta and Acianthus pusillus flower this month. If there are no flowers this year, they probably aborted due to high temperatures or excessive dryness over summer/autumn. Try putting the pots under the bench in a cooler position next summer.

The last of the terrestrial orchid leaves should appear this month although there are always a few stragglers. Tubers that formed in the bottom of a pot have a long way to grow to reach the surface. Sometimes they come out the drainage holes. If no plants appear, do not throw the pot away. Sometimes orchids take a year off and send up a leaf the following year. They are capable of forming a new tuber from the old without making a leaf. Gather together the “empty” pots in a corner. They can be left for another year or you can knock them out next month to try to establish what can be improved. Most weeds have germinated by now so weeding gets easier.

It is hard to drag yourself away from the heater this month but at least once a week go out on a wet night with a torch and examine your orchids for slugs, snails, earwigs, cockroaches, grubs and beetles. They always feed on your best orchid buds.

The SAROC Fair is in June. Clean up your flowering pots for the NOSSA stand. Other orchid clubs hold winter shows in June & July. Go along and see if there are any interesting terrestrials on the trading table.

2017 August Cultural Notes

Steve Howard writes cultural notes for Adelaide conditions. These are his notes for August; for both epiphytes and terrestrials.

WATERING

Mounts daily.

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.

FEEDING

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.

 

GENERAL

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

Additional:

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.

den-alick-dockrill-paleface-jb-1

Save

Save

Save

Save

Save

Save