DIFFERENT WAYS TO GROW TILLANDSIAS FROM SEED

By: Andrew Flower, Wellington, New Zealand

Presented to the Australian Bromeliad Conference in Adelaide, Australia, 1995

Really, I just like growing plants from seed. It is quite easy, though, to think up good reasons for encouraging seed propagation of broms in cultivation. For one thing, it is preferable to obtain nursery stock from populations bred in captivity rather than hacking container loads of plants out of their native habitat-which is often small and under threat from human adaptation of the environment. Quality control is another:
Professor Benzing, for example, notes that, "In some instances, the seedling is more amenable to adaptive adjustments than the adult which possesses inherent 'design restraints' that hinder beneficial modifications in response to a changed environment." In other words we are more likely to get species to adapt to cultivation by selected from seedling populations than by relocating mature plants from their native habitat.

This talk is specifically about raising Tillandsias, and the so-called "Tillandsia-like Vrieseas," (what the Butcher characterises as the grey-leafed tillandsioideae) from seed under adverse conditions. I will be focusing more on the general environmental conditions, such as temperature, light, water and humidity, rather than espousing a particular technique such as an Oeser stick or a Slack jar. Although I will, of course, have to bring all this into focus by describing the specific techniques I have tried, then concluding with the particular method that now gives me consistent good results. The adverse conditions I have in mind are those where the seed is not fresh and where you live in a climate far from the natural conditions in which the plants grow. Such as I experience, being reliant mainly on seed imported from overseas collectors and seed banks, and living in Wellington with cold, dark, wet winters and hot, bright, dry summers. And a modicum of wind.

Oeser Stick When I was younger I was a confirmed stick-man - nowadays I am more of an occasional stick-person. Of course, it's Oeser sticks I am talking about here. My first experience with Tillandsia seed back in the early 1970's was modelled on the techniques pioneered by Richard Oeser. Dr. Oeser supplied the seed also, and was always generous with his encouragement for our efforts (some of you may know Peter Johnson in Paraparaumu, who also started back then). We still have vegetative descendants of one little silver Tillandsia raised from his seed 25 years ago, which has never flowered and is known all over New Zealand simply as "Tillandsia species Dr. Oeser."

What I'm going to do now is to run through my recent Tillandsia growing experiences chronologically from when I started seed-raising again in 1989 after some years not growing plants at all. I hope this will show how my ideas have developed as I have modified my techniques to adapt to and overcome poor results. I have used four what you could call "gross environments" in this work: an outdoor covered shelter, a cool greenhouse, my dining room, and the latest and greatest trick known as the Incubator.

Now to the story.
At first I sowed locally collected seed on Oeser sticks, and kept them outdoors in an unheated shelter against the back fence with a fibreglass panel roof and one side left open to the weather. According to our local met. service, "Wellington is not often afflicted with fogs, thunderstorms, hail, snow, or extremes of temperature; it has in fact a pleasantly mild, though rather windy, but otherwise congenial climate...." So here we are, starting off in the "outdoor shelter," protected from winter rain but experiencing plenty of fresh air through the open side. Temperatures in summer average around 10-12C (50-54F) minimum at night, and 22-24C (72-75F) daily maximum. Winter range is 12-14C (54-57F) average daily maximum and 5-6C (41-43F) minimum (reaching 1-30C (34-86F) on 5-6 days per month and -1 to -20C (30F to -4F) on 3-4 days per year), . There is still a decent diurnal range here, which is great for growing some of the cooler growing species which will flower out here but not in the greenhouse which is 5-6C warmer on average and virtually never falls below 7C (44.6F)

Netting In this outside shelter, freshly collected seed from local TILLANDSIAS germinates fine on Oeser sticks, slabs of ponga, or on pieces of nylon netting placed in a well shaded place. Seed sown in the late spring~summer~autumn is misted 3-4 times a day if possible for the first few weeks, and germination proceeds well, with few failures from seedlings which reach the first 2-leaf stage by late Autumn and are then left dry until the following Spring. But I ran into all sorts of problems when I started importing seed. Sowing several hundred batches of seed outside on Oeser sticks and a modified Dimmitt method, germination rates were poor, and nearly all of those that did get a start failed to live beyond the three-month barrier I understand your experience with Tillandsia seed growing in South Australia.

So I started hanging my Oeser sticks up near a south-facing window in my dining room-which just gets the late afternoon sun, and placed a Dimmitt tray underneath. Many of the batches were split and portions sown on both types of medium. In general, germination was much the same, but those on the Dimmitt-type mesh eventually all died off. The idea now was to start seeds off inside, then move them outdoors in the warmer weather. Then I bought 85 lots of seed from Karel Knize in Peru, which arrived in May 1991 right in the beginning of the cold weather. The temperature in my house is not that great, and it appeared to me that the seeds were not getting enough "oomph" to germinate, so I ran some parallel experiments with a new mesic-type start-up for the seeds. This involved sowing them on an Oeser stick, which was then placed inside a closed plastic bag with three or four pinholes in it and the whole bundle then sat on an electric seed-warming tray. The temperature in here stayed at 30-32C (86-89.6F) and every day I opened up each bag, sprayed the seed with water, blew into the bag then closed it again. For those batches which germinated both in and out of the warm bag, there was very little difference in the time elapsing until germination was evident. But a significant number of batches germinated only in the bags. After 2-3 weeks I took the germinated seeds out of the plastic bags and hung them up with the rest beside the window. Even though these seeds were still only at the "fat green stage," they were obviously further advanced than their cohorts which had germinated without benefit of the extra warmth and humidity.

Sadly, many of the seeds gradually died off hanging up indoors, and I figured that they were probably lacking in both light and temperature. Obviously taking the seeds out of their warm, moist environment whilst they were still just at the swelling up stage was too soon. But I couldn't leave the Oeser sticks in there too long, because the wood started going mouldy for one thing, and for another I could only put a dozen or so batches on the warming tray at once. And anyway I didn't fancy opening and closing and blowing into a hundred or so plastic bags every day. All of this prompted a series of cognitive speculations on how to get these damn things to germinate and keep going.

The problem was defined as how to find a method which would work for all TILLANDSIAS without basic modifications for specific types, and which would work all year round regardless of the season. A lot of Tillandsia seed comes in during our cold months, and you cannot store it while waiting for the warmer weather. For me, this rules out doing it in the greenhouse since the temperature fluctuations in there are too large and the winter temperatures too low without pretty hefty modifications and a relatively large delivery of additional heating. So it came down to finding a way to start them indoors, and hold the seedlings over winter if necessary.

The solution grew out of a pretty complicated Weltungschung [spelling!] which I can't verbalise quickly. Firstly, all the other bromeliads - including the xeric Pitcairnoidea - germinate and grow on for months in a closed, warm, moist environment provided by sowing them on the surface of a peaty mixture in bottom heated seedling flats covered with a glass lid, or enclosed in a plastic bag or whatever. Once upon a time, a few million years ago, there was probably only one mother Tillandsia from whom all present (and defunct) species derive; reckon it's pretty likely her seed germinated in warm moist conditions, since her DNA would have been real close to the other broms about at the time and who were the ancestors of all the other species now about. I think there is quite a lot to the recapitulation scenario tracing back to Ernst Haekels Biogenetic Law - the concept that ontogeny repeats phylogony, the life of an individual life initially passes through the development stages of its ancestors. The theory is by no means the whole story, but there is a germ of truth in it. I visualise the first germination processes for all Tillandsia species being virtually identical, with the DNA changes that led to new species most likely being those which enabled adaption at a later stage of individual development. I also noticed that some apparently tank-type mesic TILLANDSIAS, such as T. biflora and T. variabilis which I expected to act like a Vriesea, both twice germinated for me in the mesic seedling trays, but died off just as they were forming their first leaf. I decided to start TILLANDSIAS off like all the other bromeliads so far as moisture and temperature are concerned, but to soon allow them to dry between waterings while keeping the humidity pretty high.

So for the next big batch of imports in August 1991 I decided to build a plastic tent in which I could hang the seeds - hereafter referred to as "the incubator". In effect, a large plastic bag, one with a reasonable capacity so I could keep the atmosphere more buoyant than was possible in the small confined space of the individual plastic bags, and where 100 to 150 batches could hang up once. Concurrently I designed and built a new greenhouse for growing the seedlings on. And that is basically where I am at now, although I am on to the Mark 2 incubator which was commissioned last year.

So to review: the seeds are germinated in an incubator in a totally artificial environment, located in my downstairs laboratory (so called!), and then grown on in the greenhouse. [See Appendix 1] These are some of the species which have been raised using this regime.

interior of incubator incubator Now, this is a Tillandsia incubator. Lights - twin 4ft fluorescent with growlux tubes, ballast out of the top. Timer gives a 14 hour day. That's important. I'm sure that one reason juvenile seedlings don't grow on during our winters is because the day length is too short. Light around 2,000 lux - a bit more at the top of the mesh, say 2,400 lux. A lot of the seed further down the mesh, or out at the perimeters of the box, would get much less, down to 1,000 lux or even less. That's not a lot of light. If you are sowing Tillandsia seed outside you'll be getting a hell of a lot more light than that.

Temperature. In addition to the heat from the lights, I have a 75 watt soil heating cable in a large trough of sand. Initially I used to let the temperature range from 18 to 22C (64-72F) when lights were off, 28 to 32C (82-90F) when lights were on. Nowadays I have reduced the settings to 19C (66F) on the night thermostat, 25C (77F) on the day thermostat. The reduced temperatures help me to lower the evaporation power in the air (vapor pressure deficit). Temperature and relative humidity now range around:
LIGHTS OFF: 19-20C (66-68F), 100% RH, equals 0% vapor pressure deficit
LIGHTS ON: 25-26C (77-79F), 85% RH, equals around 0.5 Kpa vapor pressure deficit

Humidity. The box has a small ventilation space around the ballast in the top - say a 5mm gap all round, and when there are no new seeds inside I lift the front door about a centimetre. Air moisture is regulated by the amount of water in the sand box - when seedlings are started, the humidity is kept at 90% or more, later I let it go back to 60-70% when some seedlings are about due to be moved out to the greenhouse. There is a lot of condensation going on inside, and the runoff is collected in a container under the incubator and then returned to the sand box.

Water. I use tap water, and adjust the pH down to 6.4 with phosphoric acid. Usually there is no fertiliser used, although I occasionally throw a pinch of Peters into the water barrel. A pressure sprayer is kept in the incubator and used to mist the seed sticks. New seed is sprayed every 3 or 4 hours for the first few days to get it started, then I cut back to twice a day: once in the morning and once in the evening. They don't seem to mind missing a day or two occasionally, although they winge a bit....

slide 2 Growing on. First rule is to leave them in the incubator until they have got at least a couple of well-formed juvenile leaves - about this stage [slide 2]. Second rule, for my conditions anyway, is to not move them out to the greenhouse between late March and early October because the day lengths are too short, temperatures are too low, and I am hardly watering at all during this period. So they can be staying 6 months or more in the incubator under these conditions. Otherwise, I move them out as soon as they are ready. Some recent examples of incubator time [See Appendix 2]

I was very interested in Dr Slack's method, described at Bromeliads 6. Eventually I tried it and had most unexpected results. If Dr Slack is around, please feel free to correct me if I get anything wrong here. For mesic sowings of all my bromeliad seed I sterilised the seeds as he outlined, with excellent results - I don't sow them aseptically, though. On TILLANDSIAS, though, last June Renate Ehlers sent me some very interesting seed from Mexico, and I decided it was so valuable I should sow it aseptically to have absolutely the best chance of getting it to grow. So I decided to use Dr. Slack's method. I had done a practical course in meristem propagation, and built a transfer case based on their designs. I sent away to Sigrna in the US for some Lindemann Orchid Basal salt mixture, and made up about 10 flasks. A little warning bell went off when I remembered Dr Slack's comment "...with Seed Bank seed I am very happy if any germination occurs". Could this be another method which works only with fresh seed? Just in case, I split each batch and sowed half in Slack jars and half on mesh in my incubator. To my surprise, germination was nil in the jars but very good in the incubator with all but one batch, where only a few seeds germinated! I didn't use all the jars, and in December I tried again, this time with fresh T. straminea seed. It germinated in both places, but whereas that in the jar is still just in the fat green blob stage, those germinated in the incubator are now out in the greenhouse with several small leaves and just miles ahead. I still have the jars with Renate's seed in them; there has been no contamination in any of them, but still no seedlings.

Transplanting. Little Tillandsias just HATE being accosted. I leave them on their original medium just as long as I can until they get just too overcrowded. As a rule, I would say 2 years minimum before you transplant them. Then I shift them onto 20-30 cm lengths of thin conifer branches (say 1-2 cm in diameter) and stick them on with PVA glue. Usually two rows on opposite sides of the stick, and about 4cm apart. Then when they get to be 4-5cm high, I move them onto their permanent individual mountings.


Tillandsia species
ex Rio Maranon, Peru, 1200m.
Seed ex Karel Knize KK8 in 1991

Tillandsia species
ex Rio Maranon, Peru, 1200m.
Seed ex Karel Knize KK8 in 1991
close-up

Tillandsias
growing on
community stick
7 years old.

More community sticks

Greenhouse Greenhouse conditions. I have a number of different areas constructed so that the seedlings are moved around progressively into areas of increasing light, and slightly decreasing humidity and minimum winter night temperature as they grow. They all get the same treatment regardless of habitat, and just get moved on through the first three stages as they grow - the only exceptions being that as soon as they start developing distinct silver scales, as in tectorum and lepidosepala, they get moved to stage 3 immediately, and then straight to stage 5 when they are starting to look like little adults. And those with soft green leaves tend to stay longer in stage 2, and stop at stage 3. The first transplant normally occurs when I move them from stage 2 to stage 3, and the second move onto final resting places (should I say rather, final growing places) is done when they get shifted to stage 4 or 5. Again, an exception is those which are developing strongly lepidote juvenile leaves and go up to stage 5 still sitting on their community stick.

Water. It is with real surprise I have listened to descriptions of the salt content in Adelaide and Perth town water supplies. (And it certainly increased my respect for your ability to grow TILLANDSIAS as well as you do) Listen carefully, and you will hear why I was surprised. But I dare not say it out too loud. I could be accused of bragging, which is of course a uniquely Australian pastime...

This is a huge topic, but I'll run through it quickly. In the greenhouse I have a couple of 44 litre rubbish bins full of water, and I water the TILLANDSIAS up to twice a day using a double action bucket pump. I put a small amount of fertiliser in the water all the time, rather than doing a stronger-strength special fertilising at longer intervals. I figure that TILLANDSIAS have such a slow metabolism that stronger fertiliser solutions will probably be effectively wasted on them, and it is more natural to feed them a little every watering. Instructions like "use 10% strength commercial fertiliser" are of marginal use, I think, so I work from the amount of Nitrogen I want to end up with. I based this originally on David Benzing's reporting of nutrient levels in natural habitats. My "full strength" normal watering target is 7 ppm Nitrogen - nitrogen is the most critical since the plants do not tolerate excess nitrogen whereas excess of the other major nutrients does not harm them. I first work out how much nitrogen, by weight or volume, is needed to achieve the concentration I want. Say you have a 100 litre container and you want to end up with 5ppm nitrogen. 5ppm is 5 mg in a litre of water, so in 100 litres you want 500mg of Nitrogen. Say your fertiliser is 30% Nitrogen, that means one gram of fertiliser has 300mg of nitrogen in it. You want to end up with 500mg of nitrogen, so that means 1 gram of fertiliser divided by 300 and multiplied by 500 = 1.66 grams of fertiliser. So that's how much you put in. And if you are watering atmospheric TILLANDSIAS, remember that organic nitrogen is of no use to plants so you must have inorganic nitrates as the nitrogen source. I use hydroponic mixes, and put 30 ml of each concentrate in each 44 litre bucket. Here is the result, after adjusting the pH down with phosphoric acid as reported by our council water-testing laboratory. I will mention quietly that total dissolved salts then reaches 130-150 ppm. I also had them check a bin in which I used phostrogen, and the results were pretty close as you can see. It cost me $270 to get these last two lots tested, which nearly finished me off! Normally I use my portable pH and total solids meters which cost about $80 each and are reliable enough for my purposes.

First, the bins get filled with tap water. I check the pH which at the moment is up around 8.5. There is an important point here. If your water is this alkaline, just putting fertiliser in the water is a complete waste of time! Nitrogen is apparently only available to plants at pH under 8.0, Phosphorous below 7.5, and sulphur and calcium at 8.0 or below. The fertiliser drops the pH marginally, then I add phosphoric acid to bring the pH down to 6.3 to 6.5. I do this for the water used in the incubator as well, but with no fertiliser usually.

Lastly, humidity. It is pretty low during the sunny weather, and in the summer greenhouse with all ventilators open and 32% shadecloth over the roof, humidity will drop virtually to 0 by 11.00am and not start up again to 4.00pm or so unless I run round with a fog nozzle. Unfortunately I no longer own a recording thermohygrograph (you can now get them which run on batteries and just store the temperature and humidity readings every minute or 5 minutes or whatever you want in a form which is read directly into the marvellous computer into a table, so that's on the "oughter get" list. (Davis Instruments in California make one) For now, I have dial humidistats and maximum-minimum thermometers in stages 1,2 and 4.

The maximum temperature in the greenhouse was also hovering around 35-36C (95-97F), getting up to 40-42C (104-107F). Last season this was causing burning to some species up near the roof (tenuifolia e.g..,) and down in stage 3 T. plagiotropica and T. multiflora var. multiflora seedlings were showing a lot of leaf-tip dieback (which wasn't caused by excess salt!). It did make T. diaguitensis flower, though. So this season I added another layer of 32% shadecloth and only used one side ventilator (leeward one) at any one time. I have also been more diligent keeping the ground wet, and the humidity on sunny days only went down to 30% and the maximum temperature rarely got up over 30C (86F). And T. diaguitensis didn't flower this year. And no die back on seedlings new growth.

Finally, two endnotes which are a bit off the track, but important. Firstly, the one Derek didn't ask me to mention. It concerns pollen storage, and I have a large guilty conscience on this one for not setting the record straight sooner. The first thing the Butcher made me do when I met him was to buy his latest Checklist, 4th edition. A steal at $6, and if you don't have it you should. Derek has added a note about storing pollen, based on an article by Don Beadle which appeared in the BSI journal some years ago. The article was misleading in a couple of ways, and I meant to correct these impressions but was a bit shy to contradict Mr Beadle in public. For one thing, he said he researched the question and all he found was advice that it was not possible to store pollen. This is not so, pollen storage is an established horticultural practice as you will soon find if you consult a basic text as e.g.. my bible, which is Hartman and Kester's Principles of Plant Propagation. Pollen life is extended by keeping it dry and cool and not storing it in plastic bags because most of them produce small amounts of gases toxic to pollen. You wrap the pollen in greaseproof paper and place it together with a desiccant in a glass container, then put it in the refrigerator. I use silica gel, which absorbs the atmospheric moisture in the jar. Olwen Ferris could have told you this, and you could have found it in the New Zealand Bulletin which is full of these little gems. I did get off my behind and send an article on pollen preservation to the BSI in January.

Finally, Derek asked me to mention my experiences with Tillandsia seed maturation. This season we had Tillandsia fasciculata, T. makoyana and T. pamelae all start bursting open seed pods and distributing apparently fresh seed. None of it germinated, although the seed was dark brown and the plumes soft and fluffy like fresh viable seed is in many Tillandsia species. So I sowed seed from pods which were still closed and had started darkening in colour and were showing just a little separation into their three segments. In here the seed itself was brick red and fat, and germinated and grew happily.

In another little group, the seed is green and fat - T. bergeri is one which is virtually viviparous in that the capsules open and display seed which is so fat it is nearly at the stage of producing the first leaf, others such as T. gilliesii and T. pieranoi (for me) do not open up until the seed is dry and unviable, yet if I open the pods prematurely I can find seed nearly as advanced as that which T. bergeri produces naturally. Strange but true. Don't ask me how you know when to open pods - its still at the level of chicken sexing for me.


Bibliography

Benzing, D.H - The Biology of the Bromeliads. Eureka, Mad River Press, 1980. p.180 and Chapter 6

Butcher, D. - An Amateur's guide to the greyish leaved Tillandsioideae. 3rd. ed. Adelaide, Bromeliad Society of S.A. Inc. 1994

Dimmitt, M. A. - Growing atmospheric Tillandsias from seed. (Bromeliad Society Inc. Journal v.40 (1990) p.17)

Flower, A. - Bromeliads in Wellington, (Bromeliad Society Inc, Journal v.22 (1972) p.131 - 136)

Haeckel, F.

Generelle Morphologie der Organismen: Allgemeine Grundzuge der organischen Formen-Wissenschaft, mechanisch begrundet durch die von Charles Darwin reformirte Descendz - Theorie. Berlin, Georg Reimer, 1866.

Hartman, T.H. and Kester, D.E. - Plant propagation: principles and practices. 3rd ed. Englewood Cliffs, Prentice - Hall, 1975

Oeser, R. - Cultivation of Tiilandsia from seed (Bromeliad Society Inc.. Journal. v.6(1956). p.3-5)

Oeser, R. - Propagation of Tillandias from seed (Bromeliad Society Inc.. Journal. v.16 (1966) p.8 - 12.)

Slack, G. - Growing Tillandsia Seed using Artificial Media and Sterile Techniques (6th National Bromeliad Conference. Proceedings Sydney 1991, p.51)

Wiley, C. - Water and Good Growing (Bromeliad Society Inc. Journal.v.26 (1976) p.60)


Appendix 1

TILLANDSIA

aeranthos erubescens mallemontii utriculata
albida exserta micans KK53 variabilis
andicola (93) fasciculata muhriae vermicosa
argentea [?] fendleri multiflora werdermanii KK32
baileyi festucoides pamelae xerographica
balbisiana flabelleta pauciflora xiphiodes
bartramii fuchsii f. gracilis plagiotropica  
bergeri gardneri polystachya  
biflora geminiflora praschekii  
boliviensis gilliesii pruinosa species Cent. Peru
bryoides globosa purpurea refiflora KK124
bulbosa hamaleana recurvata species Sorata KK120
butzii humilis schiedeana species Rio Chamasa KK141
caliginosa intermedia seideliana species Maranon KK103
capillaris ionantha seleriana species Cent. Peru KK125
capitata ixioides setacea species new KK210
caput-medusae jucunda spiculosa species nova aff.fasciculata
caulescens KK51 juncea spiraliflora KK84 species nova aff.variabilis
cereicola KK66 kolbii streptocarpa  
concolor latifolia stricta  
diguetii lepidosepala sueae  
disticha KK12 limbata tectorum  
dugesii loliacea tenuifolia  
dura lorentziana tortilis VRIESEA
ehlersiana lucida tricholepis espinosae
elizabethae macdougallii [?] usneoides hirschopfiana [?] KK42
      ospinae
      tequendemae

Appendix 2

Sample Durations in Incubator

 

A.  Summer 1995 Sowings    
    No. days  
  mitlaensis 31  
  fasciculata 34  
  fuchsii 34  
  magnusiana 52  
  caput-medusae 52  
  xiphioides 52  
  plumosa 52  
  tortilis 76  
  xiphioides 110  
B.  Winter 1994 Sowings    
  tectorum 108  
  sueae 108  
  diaguensis 108  
  lucida 138  
  pruinosa 138  
  purpurea 196  
  globosa 197  
  stricta 197  
  muhrii 243  

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