How to Grow Sarcos

The term‘sarco’ is commonly used to refer to a group of genera including SARCOCHILUS, PLECTORRHIZA, RHINERRHIZA, PARASARCOCHILUS, SCHISTOSTYLIS, PERISTANTHUS etc. (all cool growers) and even PHALAENOPSIS (namely amabilis, the only native and definitely a warm grower). The term is also used to refer to an ever increasing number of hybrids both within and between these groups. The use of this term is often incorrect.

GROWING CONDITIONS

They are grown in a shadehouse. I use one layer of 70% shadecloth in winter (maybe Easter to the October long weekend) for the rest of the year two layers of 70% are used. When I lived in Sydney the floor under my benches was a layer of pinebark while the walkways were made of river pebbles and on hot days these were hosed down to moderate temperature and increase humidity. Some protection from westerly winds  proved beneficial.

Since moving to the south Coast my greenhouse floor is simply weed mat which has been fixed to the shadecloth walls to create security from the bugs. At this stage maintaining humidity is not an issue in the new location but the weed mat is easily kept clean with an occasional sweep. I use weldmesh benches and round pots to increase airflow around the plants.

MIXES

 I have been using 12-18 mm Orchidmate (coco chips) with  20% Maidenwell Stone (diatomite) of a similar size to the coco chips. While this produced excellent results when I was living in Sydney it proved to be too moisture retentive in the cooler, wetter Shoalhaven winters.

 In early 2013 after a bout of crown rot I began moving my Sarco.s into a pine bark mix and experimented with several brands of ‘orchid bark’ finally settling on the largest grade of Orchiata which I have found to be the most consistently hard bark of those trialled. I am getting excellent growth with this product in the short term but time will tell whether it merits the extra expense and tedious task of picking out all of the pieces of wood.

 Coarse Maidenwell Stone is combined with the Orchiata at about 20% volume. This very coarse mix is shaken into the 80mm and larger pots andnever pushed in with a stick or thumbs which may result in a more stable newly potted plant but damaged roots and a drainage disaster waiting to happen  at a later stage. Maidenwell stone is becoming increasingly difficult to obtain, especially the larger grades, so an alternative such as rounded river pebbles may need to be considered in the future.

It should be noted that this is a VERY open mix designed to counter wet winters and will certainly demand extra watering in summer but it is always easier to put more water into your pots than to take it out! The extra watering requirement may also allow extra opportunities to apply liquid fertilizer.

POTS & MOUNTS

  1. Pots:     Plastic squat pots, well drained, are my preference. Watch out for fat juicy roots or pebbles blocking your drainage! Terracotta pots are also very good.
  2. Mounts:     Some species prefer to be mounted (usually Sarco. falcatus, weinthallii, Plecto. tridentata. Rhiner. divitiflora) and there are endless possibilities that will suit them. Try some of the following – red cedar, melaleuca branches, treefern slabs, cork, aged fence palings, bagasse or gutterguard pouches filled with bark. You should not overlook tying some to live trees in your garden. When mounting them you can use fishing line or stocking strips or strips of shadecloth but you must tie them on tightly, around the roots and never the stems
  3. I have recently had some success with 50mm seedling tubes cut in half lengthways and hot glued to a piece of cork or similar. A plant placed in the half tube with a couple  of coco chips seems to benefit from having the best of both worlds.

FERTILISING

As for all other natives – little and often – but as sarco’s grow year round (and especially in autumn) then winter fertilising should be maintained. I often forget to fertilise so now I apply a top-dressing of  blood and bone with dolomite in a 50:50 mixture after they are repotted  and again every few months especially when rain is coming. Now that I am using a coarse mix I am top dressing with an organic pelletised fertilizer such as Organic Life or Katek. These have the advantage of being larger particles that will not wash through the pots as readily as the blood and bone/dolomite mixture, they also claim to have extra ‘goodies’ such as trace elements.

Most fertilisers are suitable and the following have been used with little problem – Strikeback For Orchids, Aquasol, Nitrosol, fish emulsion, Campbells, Phostrogen, Peters, HSO 8, Nutricote and similar products. A little extra Epsom Salts and iron chelates occasionally does no harm. It is always a good idea to alternate between brands and always water at least once between applications of fertiliser. I have recently come to the conclusion that it is imperative to use some organic fertiliser and I find that I am using chemical fertilizers less often.

The use of lime is popular with growers who use pine bark but is not recommended for coco mixes which are not as acid as decaying bark and could see Ph rise to unacceptable levels.

REPOTTING

This can be done anytime but avoid the hottest and coldest periods, autumn seems to be the best. They like fresh mix and should be repotted at least every two years. A drench with Seasol immediately after potting seems to eliminate transplant shock.

Never compress any mixture into the pot (it is almost compulsive for humans to ‘firm’ plants in with their thumbs!) This is responsible for most drainage failures as it defeats the purpose of having an open, well drained mix. Yes, – I am nagging!

WATERING

Sarco.s have no psuedobulbs and so cannot withstand long periods without water. They are surprisingly resilient due to their thick leaves and fleshy roots which enable them to survive short dry spells and watering routines should reflect this. Lack of water is less critical if high levels of humidity are maintained.

S.  ceciliae has its own requirements preferring to be grown a little on the dry side. I used to grow them in terra cotta pots under cover and give them a good drenching then allow them to dry out.

If you were to water your orchids and then go around and tip some out of their pots you may get a real surprise as to the inconsistent job you have done – especially of you compare pots from different parts of your benches. Plants on the edges of benches seem to come off worst. Several Shoalhaven Orchid Society growers have developed a technique of potting their plants in clear plastic drinking cups with drainage holes cut out and then inserting this cup inside a conventional pot. This allows for the inspection of root growth, moisture levels and monitoring of how well you have been settling the mix in around the roots. A few such plants scattered around your benches could help take some of the guesswork out of watering.

PESTS

Sarco’s have no particular problems in this area except for S. ceciliae which occasionally becomes infested with scale. I prefer to scratch them off and keep the ants at bay as much as possible. White oil, the recommended treatment should be used with caution or you can do what I did – stop growing them!

An occasional spray with one of the newer pest oil products can be useful while phosacid seems to be an effective and safe fungicide.

Neville Roper

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