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Article by Geoff Hands

Better Culture = Hydroculture ...........

this page revised December 2003,  relating to a piece I wrote for a French Orchid Journal in September 2003

How I grow my orchids

I have grown orchids as an amateur for more than 40 years. My inclination about all things is to do them rather well or not at all . If I could not produce a few good plants which satisfy my own standards, I would turn to something else. And one of the first lessons I learnt in growing orchids is that the quality of the flowers , as well as the number of flowers, and the time they last in beauty before they fade and die, is entirely dependent on how well the plant is grown.So the first thing I had to do was learn how to grow them very well indeed. Forty years later, I'm still trying, still learning, and the elusive goal is still only a few steps away - as it always has been , and maybe always will. But It's been an interesting journey, and if a magician can wave his wand and set me back at the beginning, there may be many things in my life I'd do differently, but I'd still be growing orchids.This summarises what I have learnt :-

First class culture = the best possible flowers ( according to the genetic make-up of the plant).

Second class culture = poor flowers.

Third class culture = no flowers.

I stumbled upon hydroculture via a series of steps over a period of many years, mainly in attempting to salvage poor plants with no roots as a result of the mistakes I had made elsewhere.

I tried growing in perlite and because it was difficult to water often enough - due to other commitments in a busy working life , tried standing the pots in saucers of water. And after plants made a recovery, and went on to flower, I returned them to "normal" or conventional cultural systems - not hydroculture - only to see them go downhill again.... Finally .I asked myself why did I not grow them that way all the time ?

For several years now I have had virtually all of my collection - a few thousand plants - in hydroculture, with some exceptions ;.

The exceptions , to get them out of the way first, are that I have all my Paphs in conventional bark mixes ( for slipper orchids are different from all other orchids - some botanists even think they ought to be in a family of their own, not the orchidacea )And yes, I did try in hydroculture, but the results, although good, were not as good ....'nuff said ?

My Cymbidiums are all in rock-wool, but will go back to bark compost when I can find the time to repot, hopefully in March/April '04

Terrestrials especially Calanthe and Phaius are grown in a bark/coconut husk etc mix and Pleiones in their own bark/moss mix. Disas in sphagnum moss in standing/running water. And maybe at any one time there are up to 50 plants of assorted genera , mostly recent purchases where I have not yet decided how to grow them , still in whatever dirt the supplier used.

Finally, my Miltoniopsis proved rather difficult to adapt to hydroculture, and whilst I had patchy success, I swapped (recently) to an experimental system I devised using automated capillary matting and rockwool cubes , but although they flowered well, plants with such poor roots appal me ; I will try something different next year..

This leaves Vandas, Cattleyas, dendrobiums, all the warm-growing Oncidiniae, and a lot of species in hydroculture using static tank systems which means the pots stand in water ( with added nutrient) 24 hours per day, 365 days per year ,or hydroponics ( flood and drain).

Hydroculture - standing water is used if I think they need lower light. All the hydroculture in this manner is in the pit house (q.v.) .

In brighter lights, plants are in hydroponics using flood and drain , in my new Vanda house .

Currently I grow half my Vandas ( including vandaceous multi-generics, Mokara, Kagawara, Christieara , Ascocenda etc etc.) 1/3rd of all my Cattleyas , again including multi-generics this way.


Hydroculture - static water systems - I like this for finer rooted plants and for lower light values ; for coarser roots and for higher light I now prefer flood and drain, discussed later.

Plants have as much as possible of the old compost shaken off or washed off, and after trimming,and cleaning up in the usual way when repotting, are placed in plastic pots which are filled to within about an inch of the rim with Perlite. This is of the coarsest grade I can buy, well washed - for small quantities, place in a kitchen sieve or strainer, under a running tap. For larger quantities tip into a bucket ( I use a 15 gallon, 75 liter trashcan ) so that the can is 1/3 full. Fill the can 3/4 full with tap water, and repeatedly push the perlite below the surface. allow to stand, and keep pushing below. After a day or two, the dust and fines settle out ( discard) and the floating coarser stuff is ready to use. One or two changes of water would be a good thing if the source is a bit suspect, since Perlite is made all round the world from a variety of different ores, some of which seem to be of rather high pH until well washed.

Don't ram the perlite in , just tap the pot on the bench. Surface with a nice coarse grit - 5mm horticultural grit is good. For a rootless plant, place on top of the perlite, and hold in place with the grit.

Carefully lower the pot full up to the brim in a bucket of clean water, and then lift out to drain. This will settle the compost around the roots , especially if you tap the full pot on the ground..

Place in a saucer or tray or tank capable of holding at least 1 cm, and maybe up to 1 inch of water. Note , it is undesirable to use very shallow pots. Taller ones are better. I have used pots as much as 10 inch high , but prefer to use ones in the 4inch to 6 inch high range - I have to make my own using large pots, a saw and glue, for the larger diameters I want for specimen plants since I cannot find plastic containers of say 15" -40cm diameter or better square, which are of the right height..

It will be necessary to clean the saucer or tray or tank occasionally, and a drain in the base is handy if the tray or tank is large to handle. I make my own tanks using ply-wood and pvc pond liner - mine are 8 feet long, and either full bench width ( 30 inches or sometimes 3 feet) or half the bench width so as to have two tanks side-by-side at different levels, which makes it easier to get to the back - then they are 18 inches wide . These dimensions by the way are most economical because the standard size for plywood panels around my neighbourhood is 8ft x 4 ft. The tanks are about 6 inches deep, and then the sides stop the plants being knocked over. For a tap, I use a tank connector and a length of hose pipe. When the pipe hangs down the tank drains. When bent up into a U, it holds the water in place.  For young plants , I can pack the tank full , each pot touching its neighbours. Specimen plants need space around them - but of course this is just the same as with conventional culture.

I do find that with ordinary pots, perlite washes out of drain holes, and contaminates the water - or at least makes it unsightly. Also fallen flowers, and fallen leaves, not to mention grit from plants knocked over when I reach to the back of the bench, all make it desirable to clean out occasionally. And perlite etc will not wash down the drain tube when it is only the ordinary 1/2 inch hose. So recently I have re-plumbed some tanks using 40mm irrigation pipe and fittings - which frankly is a bit OTT , but it does mean that I can flush a tank clean with a running hose without having to take the plants out. Another improvement I have recently added, when I repot using a pot with largish drainage holes, is to cut a disc of shade cloth and put in the bottom of the pot, as a screen to keep the perlite in.

Algae - green slimy deposits can be a nuisance but is entirely dependent on light. If the tank is full of pots, and little light reaches the water surface, and especially in the winter, there is no problem. If there is a lot of exposed water surface, for example if the tank is not fully occupied with pots, and in brighter conditions, the algae is a nuisance. I think it is mainly an aesthetic problem - except that the algae is using the added nutrients! This is the reason why I have gone to flood and drain in the brighter conditions of the Vanda house, instead of using static tank systems there. And I have had absolutely no algae problem in the nearly 2 years I have been operating this.

I add fertiliser to the water to give an EC reading of 600 microSiemens (0.6 Siemens) I keep pH at about 6.0 It is best to allow some margin, i.e. work between 580 and 620 , and 5.8 and 6.2 - otherwise it takes ages to get a precise value. Note these are different figures to those quoted previously after further study of works on the question of plant nutrition , and particularly after an expedition to the rain forest in the rainy season carrying all my meters and scientific equipment and standing out in the rain for hours ( and what rain ! 4 inches in 3 hours one dark night....) taking readings.

I check values in the tanks and adjust , periodically. On occasions when I have been away for several weeks, without levelling any accusations at my local hired help who looks after things for me , I have found the pH up to 8.0 or down to 4.0 , and the conductivity over 2.0 Siemens. And I have to say that I have not seen any ill effects - so I have realised that I need not worry too much about this ,. Still its best to have it right as much of the time as possible. (Earlier versions of these notes explained some experiments I made which appear to show that water gets carried up by capillary action faster than nutrients do - and again that factor has encouraged me elsewhere to use high EC tap water with capillary matting without the ill effects I associate with its use in more conventional watering systems).I have also learnt that in nature/the rain forest/real life in the wild water and nutrients get carried up and lost through the stomata if not used by the plant at an amazingly fast rate ( per Prof.Bruno at EOC last March).

In times of high rainfall when my rain-storage tanks are all overflowing, I empty all hydro' tanks, refill with fresh clean rain, and start again to restore EC and pH levels , and do this whenever I have a free and idle afternoon - even after only a week or two. At other times, the water is not changed for 6 months, merely topped up..

I prefer to use pure water as the basis - rain water. ( After once switching from a particularly horrid tap supply to RO water and seeing a dramatic improvement in culture within weeks - but that was not with hydroculture in those days) .

Repotting is not done as a routine requirement, but only because plants have outgrown the pot, are being divided, or are lifting themselves out of the pot with root activity. I also find that dendrobiums produce such tall canes as to be top heavy and I repot just to try and get some ballast in somewhere - a good heavy pebble in the base of the pot for example.

Hydroponics - flood and drain.The big advantage here is that the water spends most of its time in a tank under the bench , so that algal growth is avoided, and the water stays clean . So I like this in my Vanda/Cattleya house where I give much higher light values. Coincidentally , these plants are also coarser rooted plants .One way of telling whether a plant likes higher light or lower light may br to look at the leaves. Most plants with hard relatively inflexible leaves - Vandas and Cattleyas like the brighter conditions. Those with thinner flexible leaves, less light. There are exceptions , but this is a simple rule of thumb useful; until you know better.

For this system I use baked clay pebbles, also sold under various trade names such as Hydroleca, Perlag, Hortag etc. Potting is as described for the static water tank system. Water and feed are the same as in the static system too. However, in potting I do not use grit as a topping. No topping at all. And by the way, this potting material needs pre-washing even more than perlite to remove the very strong (ionically) dust.

The tanks here are a little more complex than for static water, although if the on-the-bench -tank capacity matches the under-the-bench-storage tank, no valves are necessary. When the pump is switched off, the water etc drains back through the pump. In other cases valves may be needful - for example I used to run 7 hydroponic tanks from a storage tank only holding enough for 5 . So I used control valves to fill 4 tanks on one operation, and after draining , fill the other 3 on the next , and so on.

In fact this had deterred me for a long while, until I realise that ordinary domestic central heating water control valves ( motorised valves) are cheap and easy to plumb and use. I actually use 40mm plastic irrigation pipe with adaptors, but now realise this is OTT - ordinary 22mm copper pipe is easy to connect and quite large enough ( but 1/2 inch or 15mm is not - it too easily clogs with the odd clay pebble). I use capillary fittings and d-I-y, but a plumber could do it all.

The pump I prefer is one of the Hippo type - the smallest one in the range from Clark ( in UK) about 35 and is quite adequate. In fact 4 tanks each some 1.4 metres x 750mm ( 4 ft 6" x 2'6" ) filled with plants mostly in say 5" pots, and to be flooded to a perfectly adequate depth of 4 inches - 10cm , can all be dealt with by the 50 gallon (250 litre) tank quite well. I use a single pipe tee'd off to each of the 4 tanks and open to drain at one end and to the pump at the other end. Two motorised valves are used, one to close the drain when the tanks are to be filled, and which is open all the rest of the time, and one to let the pumped water in , and which is closed all the rest of the time ( so that the water could alternatively go to another set of tanks , and so on). the valves are mains voltage, controlled from simple plug in time-clocks. I find the segment kind too inaccurate, but Maplin have excellent electronic ones which can be set to the exact minute for under 10, - one per valve.

In August each tank is flooded at 8 hour intervals, and the water held for 10 minutes before draining back into the tank. The 50 gallon tank goes down maybe an inch or 2 each week. Occasionally I empty it and refill, but otherwise I check values, top up and add more fertiliser as necessary every week or two. After the Autumn Equinox I switch to once every other day , and by December reduce that to once per 4 days. In the Spring I increase frequency again in the same kind of way. When growing strongly in June/July, they are watered every 4 hours, night and day.

Below appear some other , but older results - For newest ones , see elsewhere for flowers and also look at the link below :-

1. 2. 3.

1= Dend fleckerii - bought 5 months before the pic - note the new canes already much bigger than the previous year ( the two tallest.) 5 months in hydro.

2= Dend densiflorum, var luteo-album. New cane grown since I showed the plant in flower earlier. already some 50% better than last year - this is maybe 18months in hydroculture.

3=A yamamoto hybrid, taken as a keiki in January = 7 months growth , now 12 inches high and ready to flower.


4 = Dendrobium Indomitable with canes 30 inches high - in its 3rd or maybe now entering its 4th year in hydro.

5.=Brassia lawrenceana 'longissima' with 3 old bulbs - seed-raised, I bought it as supposedly NFS. It has flowered, and now has 3 good new growths, and two very tiny ones as well.

6= Miltassia Royal Diplomat , with 8 new growths, making a 5 inch square pot bulge (badly needs repotting !)


7= A typical odont with two excellent new growths from the leading bulb but only 2 or 3 bulbs behind that. In its 3rd year in hydro.

8=Coel.mem.w.Micholitz AM - I have told this story before. But basically I have struggled with this for 10 (?) years and only grown small miserable non-flowering bulbs. You can see here the result of 3 complete years in hydro. First the bulb gets bigger, eventually making the 3 1/2 inch (9cm) bulb on the left - but always only a single growth.(That big one did flower) Now it produces two growths - one from the 2002 completed and flowered bulb and a second from 2000 bulb. Also - you may be able to just see - a third growth bud enlarging , also from the 20002 bulb.By the end of 2003 , the plant had produced 3 or 4 flower spikes ( on the earlier flowering) and 3 on the second flowering in the year ,with magnificent 6inch flowers - long lasting....

9.Catasetum cernuum. 3rd year in hydro. Made an 8 inch bulb last year, and this year's still enlarging. Not flowered yet, I think it needs a dry rest. Will try that when the bulb is made-up to 9 inch (?)


10=Miltonia spectabilis 'Moreliana' lots of leads and spikes in a plant shining with health in a 7 inch pot. It had a slow start in hydro - this is its 3rd year. Miltonias and miltoniopsis take a long time to become established with this system, but when they do - they are good indeed.

11. Aliceara Gemini Girl - the last years bulb was 8 inch high - this years still making up has half an inch to go yet to equal that .Third year in hydro.

12.Aerangis arachnoides with two spikes - start of third year.


Three Vanda pics.

13=part of vanda tank

14 showing roots wandering happily on the hydroleca

15 showing a mounted plant , still on it's bark plaque, and the whole put in a pot and grown this way.


16. BLC Mem Vida lee 'Limelight' - in hydro now for 2 years. Bulbs successively bigger now in bud for first time on two leads

17 BLC Hawaiian Passion 'carmela' note increase in bulb height etc. In its 2nd year

18 Cattleya skinneri '- one of the fancy varieties ( semi-aba , but blue - if my memory has not got mixed up with my dreams - although we all know what a blue cattleya is in 99.99% of cases...) - a seedling in a 2 inch pot ( Carter & Holmes ,via Lawrence Hobbs) here in a 4 inch pot with four leads which look to make bulbs about three times the size of the ones on when it came in 12 months ago.


This is the piece I wrote for the Paris Journal -

Hydroculture.....by Geoffrey Hands.......

I use the word 'hydroculture to mean a cultural system for orchids where the plants are permanently - 24 hours per day, 7 days per week, and 52 weeks per year, standing in say 2 cm of water ,

I have used this system with great success for Dendrobiums, Coelogyne, Zygopetallums, and some of the smaller Encyclias and Epidendrums , although most of these seem fairly easy in my conditions irrespective of cultural method . I have also used it for some of the smaller growing Angraecums, Aeranthis, Aerangis, and very many genera of botanical orchids . But it is with the Oncidiniae , especially the large group of intergeneric hybrids based on Odontoglossum or Oncidium, often with gene contributions from Miltonia, Brassia and other genera that I have had the most spectacular successes, especially those having significant contributions of Miltonia and/or Brassia genes . With many of these I have always felt that the plants were not giving me what they must be capable of until I tried this system - and now I am entirely satisfied.

I have perhaps 1500 orchids in hydroculture , several hundred of which are now in their 5th year in the system, and a few of which have been in even longer.

I find that I get very many new growths , sometimes as many as 3 from a single bulb - I have even gone so far as to thin them out in the interests of making better bulbs ! Bulbs make up to very large sizes, and the spikes are to match this , almost embarrassingly so at times, for my greenhouse in which I grow these plants has a low roof. Most important however, is that the flowers are much longer lasting , and the plants continue to grow, throwing out and developing new growths, at the same time as carrying the flowers , and without the plants suffering in the slightest.

When I grew these plants in conventional culture I often felt that I had to cut flower spikes early because the bulbs were shriveling and the plants suffering. Not any more.

The plant is potted in the ordinary way but using an inert mineral material as 'compost' . This must be one which does not take up water , and does not rot when perpetually wet .Bark will not do. Rockwool is too "dense" and stays too wet. I use Perlite quite a lot , washing this in a kitchen sieve to remove dust and fine particles , or alternatively the baked clay pebbles of 7-15mm size . These materials too need washing to remove the dust . I often top with a coarse horticultural grit , such as a silica or quartzite girt, or granite chips , 5-8 mm size , which add gravity to the pot, and stability to the plant , and are also aesthetic, as compared to the Perlite which often develops a green algal coating if exposed to light.

The 'water' is preferably pure water , e.g. rain-water ,always with nutrients added. I do not use ordinary horticultural greenhouse fertilizers or even orchid fertilizers , many of which lack sufficient Calcium and Magnesium , presumably because the makers think they will made up with tap water which probably has enough of those essential minerals.. But tap water may have too high an EC value, even before adding fertilizer. It is essential to keep the total EC below 700 mS after adding the nutrients, and clearly it is possible to add a lot more nutrients if the starting point is rainwater ! I always use a conductivity meter ( one of the Hanna range) to check and adjust. However, if your tap water is good, it may be OK. Where I live now it is excellent. When I lived 40 mile north of here, the tap water was pure poison to orchids - too much nitrate in it from agricultural run-off.

I also adjust pH ,( again using a Hannah meter ) essentially keeping within the range 5.8 - 6.2 .Figures slightly below this, e.g. 5.7 may give slightly better growth rates , perhaps because the take up of the essential micro-nutrient iron but flowering is better at the higher end of the range. However, I grow many plants in each tray or tank, and there are always some making growths, and others making flowers , so a compromise is required - hence pH 6.0 as the ideal.

. pH adjustment requires minute quantities of acid or alkali , best mixed to a weak solution, and even then added in minute quantities in a separate tank, and when correct used to part-fill the growing tray, tank or whatever.

The system works because water makes its way up through the growing media or 'compost' by capillary attraction - try placing a large cube of sugar in a spoon containing a spot of coffee, and see the coffee find its way through the whole cube. This is capillary flow - "capillary" meaning that it occurs through the minute passages between irregular pieces of the media. But those spaces do not become entirely filled with liquid , and in the case of the orchid, some air remains around the roots . If the spaces are entirely filled, as they will be in the bottom 2cm where the pot is below water level, most roots in that area will die - although I have noticed a cymbidium erythrostylum put into the system as a pencil sized growth has made a bulb the size of a hens egg, which is now about to flower, and live roots are emerging from the base of the pot , obviously well below the permanent water line. Essentially however, with the two mentioned materials at least, it seems that the 'compost' above the level of the water in the tank is maintained moist but not wet - ideal conditions for the oncidiums etc. plants.

Experiment shows that it is mostly water which flows this way, being lost by evaporation from the surface of the media , and also some is lost from the surface of the tank between and around the pots .Hence, as the water level falls, the nutrient concentration rises. The tank is therefore topped up with just water - unless the level has fallen very severely as will happen in hot weather when the plants are transpiring rapidly.

It must be the case that some nutrient finds its way up , with the water, but remember that 97.5% of the weight of a green plant is of elements obtained from pure water or from air ( carbon, oxygen, hydrogen) . Only 2.5% is from the nutrients, So a large growth can be produced from minute quantities . Most fertilizer usage seems to be overkill, or because the take-up system is relatively inefficient. However, I do not advocate using weaker solutions ; experimentally I have increased levels, year-by-year to the levels now employed, and seen better results each year . I feel for reasons rather too complex to explain here, that I have reached the desirably upper limit.

Exposed areas of the water tend to become unsightly with algae quite rapidly in high light levels, and tanks need to be cleaned out or flushed say monthly in the Summer. It is notable how the algal growth rate varies with the weather or the light level in the greenhouse ! In winter , at least in the West of England, light levels are such that algal growth is of no concern, and flushing unneccessary.

Repotting is very simple, since the fact that the compost does not rot , nor does it take up water or salts, means that a plant can be taken out of one pot, and placed in a larger one with much of the old 'compost' remaining on the roots, and new media added to fill the new pot . No serious shock to the plant ensues. If the plant likes to climb , as many do, I avoid packing Perlite above the rhizome , and instead increase the depth of the grit topping . I prefer to avoid having roots of these plants permanently exposed to air, since woodlice ( called pillbugs in USA) are a pest in my greenhouse and like to nibble exposed root tips.

I also use the system to propagate back-bulbs, which are simply treated as if they were a viable plant , and in many cases they root away , and go on to make a flowering size plant very quickly  and this is something I have never found with plants in any other cultural system

It will be understood that in hydroculture generally , all other factors of culture are as in conventional orchid growing - such things as temperature, light, air movement, hygiene, and absence of pests.

However, if Dendrobium keikis ( adventitious plants) are taken off the parent and put into this hydroculture ,and kept in the same conditions as the Oncidiae , meaning more winter heat, and of course continuous moisture , they often flower within 12 months ; but a separate problem then arises, for they flower so easily and so frequently that in this particular case the sort of glorious display , with a plant completely covered with flowers, ( which can be such a feature of D.nobile section hybrids in particular ) is never seen. I am now experimenting with hydroculture for the Summer, and a more usual dryer and colder regime for the winter for these plants, in order to try and restrain them so as to get all the flowers at once instead of a few every few months.

Hydroculture can be considered as a branch of hydroponics , but I use the latter word ( hydroponics ) to mean a completely different flood and drain system which I use for hard leaved, thicker rooted orchids grown in higher light, such as Cattleyas, Vandas etc ,

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