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.