Deflasking General
DEFLASKING
DEFINITION
This is the process whereby seedlings and clones of orchids that have been produced and raised in the environmental safety and luxury of a flask are removed from the flask and ‘introduced’ to standard orchid nursery conditions. Different cities or areas will have their own sets of cultural advantages and disadvantages to utilise or cope with in caring for baby orchids. There are probably as many ways of deflasking and caring for orchids as there are people deflasking them and most work to a greater or lesser extent. The aim is to start off by providing extra humidity, reduced light and protection from temperature extremes for a short time to enable the plantlets to toughen up as quickly as possible so that they can adjust, toughen and become as hardy as the parent plants.
Preparation Not absolutely necessary in all cases, but it often helps to remove the flask lid or bung for 3 – 10 days to expose the plantlets to drying while their roots are still able to draw moisture from the agar. This quite significantly toughens many genera. Bacterial or fungal growth is generally not a problem as the plantlets will have removed most sugar and nutrient by the time they are ready for deflasking and 3 - 10 days is not time enough for damaging amounts of bacterial or fungal growth to occur.
Removal Deflasking starts with the removal of the plants from the flask. Conical flasks usually need to be broken if the roots are too entangled to remove the plants separately without damage to their roots. Plants in straight‑sided flasks are easily removed as a plug of roots and agar without risk of damage.
Washing After removal from the flask, the agar can be removed from the roots by a moderate to vigorous stream of water from the hose with the plants supported in the hand or on a fine wire sieve. Even plants with brittle roots may have the agar removed by careful use of this technique. Generally whilst desirable, it may not be essential to remove all the agar from the roots as by the time the plants have grown large enough to deflask, there may be very little nutrient or sugar left in the agar so it will not be a source of fungal rot when potted out.
Optimal Season With a little care and some experience, plants can be removed from flasks at any time if care is taken to avoid extremes of hot and cold. I tend to prefer early autumn and early spring then cool periods in summer and try to avoid mid‑winter unless your climate or conditions are suitable then also. Growers with temperature and humidity‑controlled glass houses can deflask whenever it suits them.
Planting Out
In general I recommend against the routine use of fungicides at the time of deflasking. I believe if there are problems with fungal rot after deflasking that one should examine the suitability of the potting medium, the watering program, fertilising, temperature or humidity. Excess humidity and/or lack of air movement is a major source of fungal rot as some seedlings seem to prefer far less humidity and more air movement than others. Treating this situation with fungicide simply lets the grower sustain the seedlings for longer in an environment that is not to their liking. By all means if the situation is serious and if nothing else works ‑ use a fungicide. [ Remember we only have to grow seedlings and clones on sterile medium to avoid having bacteria or fungi spoiling the medium, not because the plantlets can not cope with bacteria or fungi themselves. ]
It is preferable to separate the seedlings and to grade and pot them together or singly depending on their size. Sometimes it is impossible to separate the plantlets without causing significant damage to many roots. If this is the case then it is preferable to plant the whole lot as an intact clump and wait for the seedlings to grow on and make new roots. At repotting time it will be fairly easy to separate the plants without damage to the new roots. Quite large plantlets are best potted singly and seem to do far better that way. Smaller ones can be planted into community pots either in rows across the pot or as a ring around the perimeter of the pot. I find that ‘perimeter planting’ permits generous fertilising at the centre and I believe that growth is faster. [ It uses more pots and takes more time though. ]
Potting Medium The medium chosen must be water retentive, hold a reasonable volume of air and not be too prone to compaction or settling. Recent experiences are indicating that clean, small‑ particle size medium results in better root growth and plant survival. The medium must be clean and free from any toxic elements. Most of the successful media have very low inherent nutrient levels that require fertiliser additions for good, balanced plant growth Some possible potting mixture components – either alone or in admixture:-
Sand - Clean, coarse river sand is an inert, draining, zero‑nutrient option.
Pine Bark - Especially in smaller particle sizes gives good results when used alone or in admixture with marble crushings, coarse sand, perlite or isolite. The bark should be of even particle size with all dust removed. I like to soak pine bark for at least a week in tap water before using it.
Sphagnum Moss - An excellent starting medium for many genera if rain water is available or if the tap water supply is not too hard or alkaline. Only exceedingly weak liquid fertilisers can be used with sphagnum moss but it is nevertheless often most satisfactory. In time the moss compacts and sours so plants need repotting to either new moss or more standard medium after 6‑12 months. Sphagnum moss is expensive so it is often used diluted with isolite at 1:1 or 2:1 probably with equal success.
Peat Moss / Perlite - Used in mixtures from 0:1, 1:0, 1:1 to 1:4, there is a ratio to suit most orchids and growers. The peat tends to remain evenly distributed through the mix and the medium is good for at least 2 or more years. Root growth is generally good and high fertiliser levels can be used if needed.
Good quality horticultural Perlite alone can be excellent to start orchid seedlings and clones of when deflasked. I have done so using deep profile pots and stand the pot in about 3cm of very dilute fertiliser solution. Deflasked orchids may need to be partially covered or may be left open depending on temperature and humidity at the time of deflasking. We have had good results with Australian Cymbidiums and their hybrids and with Paphiopedilum and Disa.
Pure perlite is excellent for many orchids especially disa & cymbidium. If deflasked into pots; the pots must be stood at all times in about 3cm of dilute fertiliser that is refreshed weekly. It is also possible to plant into an intact foam box with a 1cm hole placed 3cm from the bottom of the box so it will hold 3cm of fertiliser solution & almost full of 3-4mm particle size perlite. This produces very rapid growth of seedlings. Some cyms have flowered in 18 to 22 months after deflask.
Environment This requirement needs to be considered well as it will vary according to the orchids involved, the prevailing weather conditions, the growers watering habits, the city or area involved and local environmental effects.
The aim is to provide sufficient shade, humidity, water, air movement and pest control to enable the deflasked plants to survive, adjust, toughen and grow and to progressively harden the plantlets until they can grow alongside other similar, established plants. This is best done by consulting with growers of similar plants in similar surroundings and blending that information with your own beliefs.
Most orchid seedlings can be transferred directly from flask to humid, airy, temperature‑controlled glass houses without additional support other than lowish light levels at first. [ 10% of available light }
Most cymbidium seedlings or mericlones can be transferred directly from the flask to a, cool, shady, sheltered location in the shade house. I have done so frequently placing the pots of newly deflasked plants in wire baskets or trays supported on bricks , close to the ground under the benches for 14 to 20 days before putting them on the more protected bench areas with mature plants.
Growers wishing to deflask more delicate types of orchids can do so by placing the pots of deflasked seedlings or clones inside plastic bags. The bags can be sealed during day time with rubber bands or ties to maintain high humidity, but should be wholly or partially opened at night depending on temperature, to allow the plants to toughen and to avoid fungal problems. Close observation of the plantlets will soon reveal whether more or less fresh air is needed. I am absolutely positive we very much molly – coddle our seedlings to death. I have seen infinitely more deflasked plants die from being too wet, too humid and too stifled with too little light than I have ever seen die from dessication, low humidity, some fresh air and modest light levels.
The most reliable primary deflasking home that I have used is to take a large foam box and neatly and carefully cut the top 60mm off with a sharp knife, scalpel or hot wire. With suitable adhesive tape, fasten a sheet of gladwrap from end to end over the cut off section so as to leave a gap along both sides of about 2-4 cm. Now just replace the cut off section with its sheet of plastic in place and leave it there during the daytime for a few days but take it off partly to fully over night until by the end of 5-8 days it is left off entirely at night and by 10-12 days it is not put back by daytime. The orchids toughen up quickly without the need for fungicides. The box of orchids may be kept in a well light position indoors, in a glasshouse or outdoors in a shaded spot depending on the orchid, time of year, prevailing temperature and humidity. During very harsh conditions the time under protection may need to be extended and at ideal times some species may be put immediately outdoors alongside their parents e.g. Disa and some Aust terrestrials when deflasked in late autumn to late winter or very early spring and cymbidiums for all but the hot summer months in Adelaide South Australia. This will dieffer from genus to genus depending on the conditions where you live.
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DEFLASKING TERRESTRIAL NATIVE ORCHIDS.
The aim at the time of deflasking is to bring about a transition from the very protected and humid environment of the flask to the normal growing conditions of adult plants of that genus, species hybrid or type. This is true in my opinion of deflasking all orchids and other plants that have been cloned or raised in flasks. The transition should be as rapid as practical as the conditions that seedlings or clones are provided during the transition period are often far removed from the conditions for growing the mature plants.
The conditions that I provide to deflasked seedlings or clones even vary according to the time of year deflasking is carried out and may be further influenced by the prevailing conditions at the actual time of deflasking. For example if the weather is exceptionally cool and humid, I will provide less protection by way of artificial humidity than I would normally apply even to the extent that I may put recently deflasked seedlings out in the shade house because it is so humid and cool that seedlings may become prone to rot if left in glasshouse conditions. They would be rapidly returned to artificial humidity if the weather were to warm up or if the humidity dropped sharply or if frost became likely.
In principle, I aim to protect the deflasked orchids / plants to assure they do not dehydrate or suffer burning by sunlight or other damage but I intend to harden them off over 2-3 weeks by which time they should be growing in identical or just slightly more protected conditions than are ideal for adult plants of the same type. I am certain that most seedlings that die do so from over wet, over humid, under-ventilated, poorly light conditions and that very few ever die as a result of dessication..
My process is to remove the seedlings from the flask as logical and that may range from :-
- Knocking the lower agar containing region of the flask against my hand reasonably forcibly to compact it so that the plants can be drawn out through the neck without damage to
- Using tweezers to remove some, most or all of the seedlings through the neck without damage before getting the rest of the agar and any smaller plants out to
- Wrapping the flask in newspaper prior to breaking the base or upper section of the flask by a hammer blow.
After removal from the flask I lay the seedlings on a sheet of taught fly screen [ Nylon or aluminium rather than copper ] or on some shade cloth laid in a wire frame basket and wash the medium off the tubers / roots by means of a controlled jet of tap water from my garden hose as the medium may promote fungal infection if planted into the substrate [ potting mix ] with the seedlings.
Many hobbyists lay their seedlings on a sheet of paper or dry towel to dry out at this stage before proceeding to plant them up and assure me that this enhances their subsequent success, so that may be worth trying. I have not needed to do so but it may be appropriate to do this with your orchids and under your conditions - you may try a few this way to find out.
I like to deflask terrestrial orchids into sphagnum moss but am aware that many others deflask into the type of soil mix that they find grows their mature plants best. Caladenias may prefer soils or sands that have been taken directly from a wilderness area but excellent results have recently been had using sphagnum moss. A lot depends on the way one waters and fertilizes from now on and sphagnum seems to be very good if you avoid saturating it and if relatively deep and broad pots are used. Once seedlings have hardened off and become more robust it is practical then to repot them into your preferred potting mix for the type of orchid involved. The real secret seems to be to keep the moss just moist and no where near wet while it is really cold and humid and to grow them where there is regular, good air movement.
1. Pterostylis. It is my experience that most, if not all, species and hybrids of this genus do best in sphagnum moss. They generally tolerate moist conditions better than most genera.
2. Diuris. It is my experience that this genus also does very well in sphagnum moss but when the plants have produced large tubers, they might grow better in wilderness soils or sands with some leaf litter at the surface. Some no-fertilizer potting soils intended for garden planter boxes or for indoor plants can be good for these orchids also but one should first test to see if they are OK by trying just 1-2 plants out at first.
3. Thelymitras. Same as diuris but generally easier to succeed with than the diuris.
4. Caladenias. These have been the greatest challenge with success of any real note only quite recently. Until recently and perhaps it is still so, they always do best when planted out adjacent to parent or mature, similar plants.
Recent experience with sphagnum moss or well washed, coarse sand + 10% peat moss has also been encouraging. A key factor is to be sure to keep them on the rather dry side and to put them in a breezy location immediately so they don’t rot. A roof or cover to avoid rain seems to be essential but the sides must be open to allow free air movement.
Ideal deflask time is mid to late autumn to late winter or very early spring as these orchids are active during southern Australia’s winter and spring when temperatures are low so this is the ideal growing period for deflasking.
I sort the seedlings out and grade them and may choose to pot large specimens with a tuber into singe 3” diameter x 5-6” deep plastic pots. I may choose to put smaller or the whole lot, irrespective of their size into an 8-10” wide x 8-10” deep community pot.
The sphagnum should be put in firmly only for the bottom 1” to prevent critters such as millipedes, slugs, or ear-wigs from getting in via the drainage holes. The next layer up to planting depth is placed quite loosely and I put a little at the upper edge and then start planting the seedlings by putting them so that the leafy region will be above the sphagnum with the stem / roots / tuber buried in the sphagnum. I then put a wall of about ½” of sphagnum in and plant another row of seedlings against the wall taking care to leave adequate space between plants for air movement. Another wall of sphagnum goes in against these seedlings and another row of seedlings are placed against it and so on until the pot is full or you run out of plants to pot. I have found that including about 5mL of old, crushed up leaf litter is a great nutrient source for these orchids and I add it as a lump about 50mm from the base of the pot during potting.
The sphagnum or soil mix that you have chosen to use should be damp but not wet. Sphagnum moss may be squeezed out so that is not excessively wet.
Rarely required, protection from drying can be achieved by putting the pots of deflasked seedlings into styrene foam boxes that have had the upper 2” section cut carefully off. The cut off section then has a sheet of ‘cling wrap’ plastic run over it from end to end and is fastened to it with adhesive tape. I like to have about ½ - 1 inch air gap along the sides. The top section with plastic sheet attached is then replaced on the box by day and lifted off by night. If it is very cool and humid then the lid can be left off by day also. If fungal rot begins then more air movement is needed. It may even be ok if there is nil frost risk to put the plants outside in a covered part of a shade house until the weather becomes warmer or less humid.
Conversely if the weather becomes hot and the humidity is low it may be necessary to leave the lid wholly or partially on overnight. Generally one is aiming to protect them enough so that they don’t dry out, stress and die but to put them under reducing protection so that they can be hardened off in 14 - 21 days. Fungal attack indicates it is too humid or there is too little air movement. Light levels should be roughly suitable to grow indoor plants or African violets.
After the 14 - 21 days hardening off I transfer them to my benches under 75 to 50% shade without protection from rain and where it is breezy though prolonged wet winters are a problem so some protection from rain seems necessary. Often some pterostylis plants that are deflasked in mid to late autumn will flower in mid to late spring. Thelymitras and diuris amy take until the next or subsequent season to make tubers large enough to flower.
Fertilising
There are 2 elements in my fertilizing program.
1. I may place a little natural bush litter [ bark and leaves collected and partly decomposed ] into the pot about 1” from the bottom or may poke a hole near one edge of the pot and pour some fine litter into it and tamp it into place and cover it with sphagnum or soil mix as it breaks down slowly while the mix is damp and provides nutrition as it does so.
2. Mineral fertilizers at very high dilution can also be applied safely when watering or moistening the mix. I recommend about 5-7 grams in 10 litres of rain water or if using mains water do not exceed total dissolved solids of 500 - 700 PPM . Ideal fertilizers are the Campbells range of NPK fertilizers and the exact NPK values are somewhat irrelevant at this high dilution. Any other purely mineral based fertilizers like Campbells are also likely to be ok. Here in Australia I use and recommend Thrive, Aquasol, Phostagen, Campbells, the HSO range and any others that are similar to them.
Application. I use a solution of 5-7 grams in 10 litres of water to moisten the sphagnum or soil of the newly deflasked seedlings immediately after deflasking and as needed to just keep them moist thereafter until they are put outside when I water them with the same solution when they need watering. Once outside, they can be watered so some pours out of the pot or the pot will ‘salt up’ if not flushed.
The above can also be applied to deflasking disa orchids and vice versa but keep Oz terrestrial drier.
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DISA DEFLASKING
This seems best done in spring or autumn but may be done at almost anytime if care is taken. I have even had excellent results in our hot summer [17oc nights and 25 - 420C days]. Occasionally some seedlings deflasked just prior to winter will flower 7 months later.
1. Remove the flask lid and leave it half covering the flask for 2- 3 days before deflasking. { This step is optional. In ideal, cool weather deflask directly. ]
2. Immediately before deflasking, wet the leaves with water. (Leaves are covered with fine hairs which cling to glass or plastic and may cause damage during removal from the flask unless wet.)
3. Grasp the plants gently as a clump by the leaves and use a garden hose at reasonable pressure to thoroughly squirt the agar from amongst the roots. Gently rinse any agar from the leaves.
4. Lay the seedlings on a tray with a few mm of water top prevent drying and carefully try to separate plants from each other but be careful as they can be broken quite easily. If roots are too tangled, just separate those that can be parted and plant the rest as clumps in community pots [ 4 or 5 inch wide pots ]to be separated later at repotting time when they have grown stronger.
5. Place all strong plants singly in separate 90mm wide x 100mm deep pots and smaller plants in 4” pots or community trays of teased sphagnum moss. Plant so that the roots are only just under the surface of the sphagnum. Water well with dilute fertiliser as you deflask so plants don't suffer from drying.
6. One option after potting and watering is to place the seedlings in an area that is sheltered and protected from heat in good indirect light. Pots may be placed in plastic bags which are then opened a little each night to toughen the plants. After 2‑7 days, leave the bag slightly open during the day as well, increasing the opening size each day until fully open at or before 10 days. Remove the pots from the bag or leaf rot may start. Water only to keep growing medium moist. Use dilute fertiliser [ see next paragraph about every third or fourth watering.
Rather than using plastic bags, I tend to use large, deep foam boxes to house newly deflasked disas. Make a mark on the foam box at the exact height of the top of a 3 inch or 4 inch pot and then take a very sharp knife and cut through the foam all the way around the box at the same height to leave a foam box base and a cut-off top section. I run a layer of thin plastic 'cling wrap' from end to end over the top of that cut-off section and use adhesive tape to fasten it in place at each end of the box and find there is an air gap of 2-3cm between the sides of the box and the edges of the plastic sheet. This is great as it lets some fresh air in but maintains some humidity while the seedlings toughen up. The pots of deflasked seedlings are placed in the bottom part and watered with dilute fertiliser then the top section with its plastic sheet attached is replaced on the base. It is left this way during warm, dry days but is removed at night or on cooler days to let them harden off as quickly as possible. After about 1-4 weeks depending on the weather and just how quickly they are hardening up, I put about 2-4 cm of the dilute fertiliser solution in the foam base and transfer the seedlings outside under 50 -75% shade cloth with the mature plants. If you have problems it is likely to be a combination of too much humidity &/or too little air movement &/or insufficient light. Watch closely and reduce humidity & increase air flow iat first sign of rot or fungus
7. Very dilute soluble, mineral fertiliser at one heaped teaspoonful to 40 litres of water plus half a teaspoonful of Magnesium Sulphate and about 1/8 teaspoon of soluble Iron Chelate has given excellent results with both seedlings & mature plants.
8. Disa seedlings may grow to flower during the following season. The few plants which flower so young before making a tuber are likely to die after flowering without making a tuber or stolons. Most seedlings however make a tuber first then flower in the following season. Some vigorous varieties will produce 1‑5 good sized tubers in their first year.
FERTILISER. Disas detest strong fertiliser but benefit greatly from use of simple weak mineral-based fertilisers. I use any balanced commercial soluble fertiliser brand diluted at one heaped teaspoonfull to 40 litres of rain water [or a diluter which achieves this dilution] + Magnesium Sulphate & Iron chelate as per 7. above. Fertilising weekly to fortnightly seems to be adequate.
I suspect organic fertilizers, slow release fertilisers & pelletised fertilisers have killed more disas than any other problem. Don't use them unless you can afford to lose some or all of your disa collection.
PESTS. Disas are largely free from predation by insects. They may be susceptible to aphids for up to 3 months after deflasking. 'Folimat' used according to directions on the pressure can works wonders. Green & brown grubs can damage some plants and again 'Folimat' and vigilance works well. Slugs & snails cause occasional damage to flowers or buds and sometimes take a fancy to the odd seedling or two. 'Black Birds' are the greatest threat by far in that they tend to dig the sphagnum moss out in search of food and nesting material. Fine plastic 'bird‑mesh' soon fixes the feathered fiends.
REPOTTING. In the potted situation, Disas grow best in sphagnum moss. They have also been grown using hydroponic systems and ‘Perlite’, or using low potency, well aged, potting mixes and acidic wilderness soils. It is best to repot each year in early to mid autumn. Handle plants carefully as rough handling can break the plant from its tuber.
CULTURAL CONDITIONS. Disas enjoy temperatures from just above freezing to 40o C. They like free air movement and prefer low rather than high humidity.
They like quite high light levels and can tolerate full sun in southern Australia. Generally 30 to 50% shading would be most suitable.
They can be grown in glass houses provided there is constant air fresh movement throughout the day. My own glass house where breeding stock and some deflasked seedlings are kept runs from 20C in winter without air movement to 380C in summer with evaporative airconditioning running during daylight hours. Other plants do very well out doors under 50% shade cloth in open, airy, sunny conditions.
Rain water is best but on some plants I have been using our local reservoir water which is hard, chlorinated and ranges in pH from 6.4 to 8.4 without problems over the last 4 years.
Disas are most rewarding orchids to grow. They flower from mid spring to earLy autumn and make ideal pot plants, cut flower producers and show‑bench orchids. They are very easy to grow. There are miniature, intermediate and standard sized flowers in a wide range of clean, clear colours & there
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