Monday, January 31, 2011

Lycaste aromatica

Another acquisition at the EPOS meeting in January was a Lycaste aromatica. Seeing as the evening's talk was on this genus, it seemed only appropriate - and it has a very interesting cinnamon scent! Unfortunately, a slug or snail seemed to have had a field day on the blooms, but the plants looked otherwise healthy.

Lycaste aromatica
Defensive spikes
This species is one of the deciduous ones, meaning it loses its leaves during the dormant period. Interestingly, deciduous Lycaste species have spikes on the top of their pseudobulbs. Apparently, they are native to areas that get pretty dry, so I guess a fat, green, juicy pseudobulb would otherwise make a tasty treat for some herbivore! After dropping their leaves, the deciduous Lycaste species should be kept almost dry. The American Orchid Society has a useful culture guide, available here which outlines all their requirements.

Phragmipedium caudatum

The selected specimen @ EPOS meeting
(Nokia E71 camera,--)
At the EPOS meeting, I immediately noticed some fantastic Phragmipedium specimens for sale, and decided I had to have one before anyone else had a chance to get one; after asking Johan who one spoke to about getting plants, he found the member who was selling them (unfortunately, I can't remember her name), and handed over my money, selecting what I thought was the "best" of them on display. This member also entered a spectacular pot of Phragmipedium caudatum into the show.

This specimen has entered the OOAB menagerie (there should be a word like that for plants!):

Phrag. caudatum
Close up of the "slipper"
Sadly, I returned from a 2 day out of town business retreat on Friday to find the flower had fallen off before its time (although we suspect it may have been accidentally dislodged by the cleaning lady) :(
Big pot 'o Phragmipedium caudatum @ EPOS meeting
(Nokia E71 camera,--)

Phragmipedium orchids are native to central and south America, generally growing in fairly densely shaded and damp environments; most Phragmipedium apparently like to be kept quite "wet" by orchid standards. Phragmipedium caudatum, however is epiphytic and doesn't like as much water; it also likes more light than a lot of others (up to 3,000-4,000 fc). They like 50-70% humidity. They don't like mineral rich water, so Grahamstown's Finest is right out...! Weak fertiliser (25% strength) and the occasional pure water flush-through seems to be a good idea. Temperature wise, most are "intermediate" growers.

New Gadget: Light Meter

Tenmars TM-202

I've been trying to learn about the light levels needed for various orchids to grow happily. "Quantities" like "50% shade" don't help very much when you don't have a greenhouse or shade-house. However, many orchid light preferences are available in a unit called a "foot candle", which of course the human eye is ill equipped to assess.

Fortunately, there are toys that can help with that... I bought a Tenmars TM-202 from, and have been happily wandering around the house thrusting it in the general direction of windows everywhere...!

I knew that Phalaenopsis were fairly "low light", whilst Cattleyas were fairly "high light", however, equipped with the knowledge that foot candle requirements of many plants were known, I set out to figure out what was actually needed. A bit of judicious googling yields this handy reference for the genera and intergeneric hybrids I'm growing:

  • Angraecum: Species dependent; sesquipedale: 2,500-4,000, apparently preferring very bright light, perhaps with morning sun.
  • Ansellia: 2,500-5,000, apparently preferring very bright light, perhaps with morning sun.
  • Ascocentrum: 3,000-3,500, apparently preferring very bright light, perhaps with morning sun.
  • Beallara:
  • Cattleya: 3,000-3,500
  • Cymbidium: Standard: 2,000-4,000 Miniature: 1,000-3,500
  • Dendrobium: 1,500-4,000 (kingianum is probably at the upper end of this)
  • Disa: 1,500-2,000
  • Laelia: 2,000-3,500
  • Laeliocattleya: Presumably takes into account their ancestry, so 2,000-3,500
  • Lycaste: (deciduous spp) 2,000-4,000
  • Oncidium: 2,000-4,000
  • Paphiopedilum: 2,000-3,000
  • Phalaenopsis: 1,000-1,500
  • Phragmipedium: 2,500-3,500
  • Rhynchostylis: ~3,000
  • Sophrolaeliocattleya: Presumably takes into account their ancestry, so 2,000-3,500
  • Stenoglottis: 2,500-3,500
  • Zygopetalum: Similar to Cymbidiums, so 2,000-4,000, probably at the upper end

So, all in all, it looks like I need to get more light in here...!

Incidentally, you can get an idea of the light intensity using a camera's built in light meter - at least if it displays the exposure it thinks is required. Using a piece of white paper, with the camera lens at a distance of about 30cm from the paper, at f2.8 with a film speed of 200, the shutter speed is (very...) approximately equal to foot candles. If that sounds like too much maths to you, First Rays have a handy form you can fill in that works it out for you.

You can also work this out at any settings with the following formula:
where F = F stop (aperture)
I = ISO setting
E = Shutter Speed (exposure)

I did this in my office, and I got:
6 * 2.6*2.6 /(80*1/33) = 16.731 FC (wow, that is dim).

If you don't have a camera with an obvious light meter, even your cellphone camera will give you this information if you can read the EXIM data (on my Android phone, I can see these details for each picture by tapping the menu button, then tapping Details and scrolling down); again, take a picture of a plain white sheet of paper with the lens about 30cm away and filling the field of view.  

Friday, January 28, 2011

New plant: Oncidium

At the last meeting of the EPOS, just before I was about to leave, Abraham Marais very generously gave me a spectacular Oncidium sphacelatum. I immediately forgot the particular species/hybrid name [Edit: I found out!], but will find out. Anyway, here are some pictures of it in its new home and a closeup of one of the flowers.

New Oncidium sphacelatum dominating the OOAB collection.
Part of one of the long racemes of flowers.
Close up of one of the flowers.
Oncidium is a fairly large genus of some 330 species, native to Central and South America, with a few species extending into the Southern USA. A fairly comprehensive guide to suggested culture of this group can be found here.

Tuesday, January 25, 2011

More fungi...?

Our Rhychostylis coelestis seems to have some kind of fungus growing on a few of it's leaves. Yesterday, I decided enough was enough as it seemed to be spreading. I sterilised some scissors in something called "Grovisan", which is apparently similar to Physan. I then cut the three dodgy looking leaves off, dusted the ends of the cut with sulphur, and sprayed the whole plant with a fungicidal spray consisting of 1ml of Benlate, 1ml of Previcur and 1ml of a wetting agent called Bladbuff. I then re-dusted the ends of the cuts with sulphur, as the spray washed some of it away. I even dumped the dodgy leaves in Grovisan (and re-soaked the scissors) before tossing the leaves in the bin.

Here's what the dubious leaves looked like: 
Closeup of the worst affected leaf; this was "weeping" fluid just after I cut it.
Underneath the leaves.
Upper side of the leaves. Note the top one has a long "blister" spreading out from the dark spot.
This plant had some Captab or Dithane (4g/l WP; actual concentration 2g/l) - I can't recall which one was sprayed on it a few weeks ago, but that didn't seem to really stop it. We used to spray the leaves of all the plants a few times a day (never in the late afternoon/evening though) to "increase humidity" in the balcony, but I've decided this is a bad idea. We'll now just be spraying the exposed roots of the Ascocentrum and this Rhynchostylis rather than the whole plant. Hopefully, this will minimise the chances of any fungal or bacterial rots. With a mist humidifier, we should be able to keep the humidity in a range where the orchids will be happy without spraying the leaves with water. On really hot days, we may still spray whole plants, but we'll see how it goes!

I really really hope this is a fungus, not a bacterium, as those seem much harder to treat (and I don't think I have, or can easily get, anything that does).

Friday, January 21, 2011

Some names for some "mystery" plants

I emailed the Exotic Plant Company the other day, and I received a detailed reply from the owner, Michael Tibbs this afternoon:
Hi James 

Thank you for your email.

The Zygopetalum is a hybrid called Zygopetalum James Strauss

The spotted Paphiopedilum is Paphiopedilum (Bagley x insigne)

The albino Maudiae is Paphiopedilum ONYX (Maudiae x Goultenianum)

Trust this offers answers to your questions and well done on your website…

Best regards


I also sent emails to Lansbergen Orchideeen (who have yet to respond) and  PP Orchideeen, who sent me an email this morning:
Hello James

I have looked at de foto.
We called it a Amerikaan Hybriden (complex Hybrid)
It is a mix of diverd Paphiopedilum,

Best regards
Elsbeth Prins

Looks like Mr. Tibbs knows his orchids better than the people who grow them... Many thanks, Michael, and thanks to Elsbeth for at least taking the time to respond! Time to update ye olde species list.
Paphiopedilum Bagley x insigne
Zygopetalum James Strauss
Paphiopedilum ONYX (Maudiae x Goultenianum)

Eastern Province Orchid Society

The EPOS logo
I've just returned from a dash down to Port Elizabeth and back for the first meeting this year of the Eastern Province Orchid Society (EPOS), which we signed up for last week.

This month's talk was by Chris Randlehoff, an accredited SAOC judge and clearly quiet a major orchid grower too - he even won the South African Orchid Council's Orchid of the Year award in 2009. Chris traveled from Eshowe in KZN to talk about the genus Lycaste and its hybrids and some closely related genera (Ida, Anguloa) with many, many picture, noting what made "good" plants in a judge's eye and also culture requirements. It's quite amazing to see the vast variety of orchid hybrids that have been made from just a few original species in this group. He noted that fertilising most orchids with additional Calcium and Magnesium had generally made his plants much stronger, so we might just have to try that! I also noted that all the plants that weren't strict species didn't have italicised names (not even the genus) - so I've got some editing to do...!

After the talk and tea, Chris went through each of the plants members had brought with them, commenting on their appearance and culture, sometimes suggesting things members might do to improve them; with several plants, he noted that they were "The Best XYZ he's seen in South Africa" - so the EPOS members evidently know what they're doing!

The society is very friendly, and many of the members brought along some spectacular specimens from their collections. I think the most spectacular were a bowl filled with the same species of Phragmipedium I bought, some fantastic Vanda hybrids, a large Mokara and an incredibly deep purple Dendrobium phalaenopsis hybrid - but it was pretty hard to choose what was best!  "What orchids do you grow?" is evidently the preferred opening question at orchid clubs (quite understandable!) - I almost felt I should have had a species list with me, but as much as I think we might be going a bit mad in our "balcony rainforest", we're not only rank amateurs, but scarcely have any plants compared to many of the members. So if anyone wants a list, well, here's my blog, and there's a plant list in the Orchids tab at the top - which I now need to update! :) The members are also generally keen to not only talk orchids, but pass on tips and experience, which is a pleasure. Unfortunately I can't quite remember all the names of the people I spoke to, but I did have a chat with a guy called Stan Wedge, who was recently made an Honorary Life Member of the society. He started growing orchids in 1978 - the same year I was born. He's also no stranger to national awards, winning an orchid of the year for his Dendrobium kingianum "Stan' in 1999, and species of the year in 1993.He also said that he had "about 600" flasks of various things around one of his growing rooms, and makes his own flasking medium out of a fairly long list on ingredients. If he has 600 flasks, I can only imagine how many actual orchids he must have... Hopefully, we'll have something worthy of talking along to the next meeting! I had considered taking some plants along, but I was in a bit of a rush to get there, and some of the orchids (the paphs, Zygopetalum and the Ascocentum) are a little past their best - or not quite there yet (the Slc. Kagaribi Dawn 'Red Star'); I also didn't feel happy taking one of "our" plants when it was just me attending!

I bought two orchids, a Phragmipedium caudatum and an aptly named Lycaste aromatica. I've wanted a Phragmipedium for a while, and the idea of having one of the species covered in the talk appealed - as did its intriguing cinnamon scent!

I asked the club's chairman if he might be able to bring me a few items from the EPOS Shop to the meeting, which opens twice a month on Sundays; as we're going to a wedding in Cape Town this weekend, we couldn't really make the next open day (this Sunday), and they sell some quite useful stuff which we need (like an acaricide for adult red spider mite, and some other fungicides I can't find here), which he kindly did.

On my way out, the chairman (Abraham Marais) asked if I might like the Oncidium he had brought for the show table - I said I would rather, and asked him how much he wanted for it, but he point blank refused to let me pay him for it - so many, many thanks Abraham! He noted that he had "quite a few" - and by "quite a few" he meant about 100! My brain has forgotten the exact species, but I'll find out [Edit: sphacelatum]! Apparently it got relegated to the garden in a shady spot under a tree; this particular specimen has quite amazing sprays of yellow and brown flowers - seemingly hundreds of them - it's a stunning specimen that pretty much filled the back seat of the car. 

No pictures just yet, but I'll post some early next week.

Thursday, January 20, 2011

Graphing the interSeptor

After a considerable amount of mucking around, I persuaded various things to work together, and I now have Cacti making nice web-accessible graphs for me. My next project is to get a small "widget" display for OOAB that shows Current/Max/Min/Av values for temperature and RH.

If anyone ever needs them, the Jacarta interSeptor SNMP OIDs you need to read the Temp and Humidity are:
. = current temperature
. = current RH 
The values need to be multiplied by 0.1 to get a real temperature, as it stores the value as an integer with .1 of a degree increments.

Basically, the steps are to:
  1. Get a dyndns account or similar and make your router use it (if your machine/router/ has a dynamic IP address)  
  2. Use the port forward/firewall function of your router to forward any SNMP requests (port 161) to your interSeptor's internal IP address
  3. Install Cacti
  4. Use the SNMP OIDs to create graphs. 
  5. Because cacti uses dynamic references to its graphs, you're going to need to publish the graphs somewhere using the built in FTP function, or publish them to another web-accessible directory on the server running cacti. 
Relative Humidity
(these are still a work in progress)

New Gadget: Jacarta interSeptor

Today I received a Jacarta interSeptor from RS Components, which I plan to use for monitoring the balcony's temperature and humidity levels. Essentially, this (rather pricey) toy sticks a thermometer and hygrometer into a box that speaks http. I could theoretically add another sensor to monitor temperatures and humidity elsewhere (like in my wine rack!) but the optional sensors are also $$$.

The little sensors can be on the end of up to 20m of straight through Ethernet cabling, and the interSeptor unit itself can be anywhere with a network point and some power (why the heck don't they support PoE?!). You can also use the sensors to monitor high/low or open/closed circuits, so you can interface them with other things, along with a host of "official" sensors.

The sensor specifications recommend operating temperatures of 0-80ºC and 10-90% RH. You can set alarms ("thresholds") from -15 to 65ºC and from 5-95% RH. The accuracy is stated as +/- 1ºC and +/- 3% RH, which seems adequate for my purposes (although the RH could do with being a little higher).

Several somewhat minor but quite frustrating things immediately hit me:
  1. It has a Fat Plug (aka "wall wart")
  2. It's an English-style Fat Plug, which doesn't plug into sockets in South Africa
  3. It doesn't work like they say it does.
I hate Fat Plugs with a passion. Fat plugs are generally a major pain in the rear end to fit into multiplug adaptors. Having a UK plug on a product sold in South Africa is somewhat annoying - fortunately, I had an adaptor lying around I could use. That was a minor inconvenience compared to trying to talk to the thing.

In terms of "not working", theoretically, the interSeptor should use DHCP to pick up an IP address. However, for some reason, v2.03 of the firmware for these devices doesn't actually seem to work with DHCP servers (I tried two different ones, one on a Mikrotik router, and one on a Netgear router). With the Mikrotik, I could see the DHCP server offering a lease, but the interSeptor wasn't accepting it (or rejecting it) - it was point blank refusing it.

I wrote to their technical support, explaining the DHCP problem. They sent me the latest version of the firmware, v2.08. Of course, there's a bit of a Catch 22 here, in that if it doesn't DHCP, you can't upgrade the firmware, because you can't actually connect to the device... To their credit, they respond pretty fast!

Solving intractable problems like this often takes up chunks of my time at work, so I thought I'd try a different approach. I have a Sunix USB to Serial (RS232) adapter, and as the interSeptor comes with a serial cable and instructions on how to configure it through there, I thought I'd give it a try - after downloading drivers for Windows 7, and TeraTerm, as HyperTerm is no longer part of Windows. No joy at all on either COM port, or plugged into either of the 2 serial ports on the Sunix adapter. Irksome.

Being a network device, these little gadgets come pre-configured with an IP address, so as a last ditch attempt to connect to the blasted thing, I decided to try changing my computer's IP address manually to something within the same subnet range as the pre-configured IP on the interSeptor, and simply plugging a straight Ethernet cable between my computer and the device. This, of course, worked. I upgraded the firmware, and now the device quite happily talks DHCP.

Now comes the frustrating bit...!

The whole point of getting something like this is to let me keep a virtual eye on the plants when I'm not at home. What I'd like to do would be to have the device accessible over the Internet to Those In The Know (i.e. me). It would also be quite cool to have a little applet that sits on the blog here showing the live and historical temperature and humidity levels.

Whilst I can make it work oh-so-happily on the LAN (from either of the two subnets) I *cannot* persuade it to talk to the broader "internet". I have yet to pin down whether it's an issue with the Netgear router not doing it's firewall rules correctly (tried updating that to the latest firmware!) or that the interSeptor only responds to local (RFC1918 addresses), or those within the same subnet - given that I have NAT between the two subnets here, no matter which one I'm actually in, the devices on the other side will still "think" I'm in their subnet.

I've spent pretty much my whole evening on this now and am feeling like it's time for bed. There *must* be a sneaky way I can get information out across the Internet that doesn't rely on me setting up email alerts - but that's a job for another day... SNMP might be the way (and the included CD has the MIB).

The little Java viewer applets are quite cool, but only available within the LAN so far :/

These gadgets have a lot of promise, but so far, GRRR!!! To be more useful to gardeners, they should make the sensors weatherproof, make them work with DHCP (which they have done - IF yours has the right firmware) and I think the sensors could do with measuring up to 100% RH.

This "review" might seem a little negative at the moment, but I'm sure as soon as I have it worked out, I'll be singing its praises...!

Wednesday, January 19, 2011

Under (Water) Pressure

Given the somewhat terrible water around these parts, and rather than spending a small fortune buying distilled water from a pharmacy (or begging it from people who have lab grade distillers or RO machines), I've been considering getting a fairly hefty Reverse Osmosis (RO) unit, not only for the benefit of the orchids, but also the fish (who currently get bottled water, as do the rats), and of course, the humans around OoaB.

When I asked for a quote and about the need (or otherwise) for a pressure booster pump, "The Waterboy", Marco Justino, based in Durban, said that this was not required as long as the incoming water pressure was over 3 bar.

I said I'd try and figure out a way of measuring the water pressure here and get back to him.

I spent a frustrating 30 minutes or so going around all the places that might conceivably have a pool filter pressure gauge. None did, not even the pool shop. Eventually, I thought laterally and wondered if I might persuade a car oil pressure gauge to work (at least briefly); a quick trip to Midas and R90 later, I had a gauge that could read up to about 7 bar. A few Gardena hose fittings on top, and I had what I hoped would be a workable water pressure gauge.

Oil pressure gauge and Gardena fitting
Conveniently, one of the fittings that came with the oil pressure gauge happened to be just about the right size to self-tap into the plastic of the Gardena fitting. Yay!
Ooer, it actually works!
Somewhat to my surprise, the jury-rigged gadget worked, and showed the pressure on the cold tap in the bathroom to be about 4 Bar (coincidentally enough to just pump a column of water about 40m into the air). Why the hot water pressure in our house is therefore so totally pathetic (taking a hundred years to fill the kitchen sink and giving us showers worthy of the worst in the UK, legendary home of pathetic water pressure), I don't know, but I suspect is has something to do with the geyser (immersion water heater) that looks like it was wrought out of lead, by gnomes at work deep in a mine, in about 1824.

So it looks like there's enough pressure for RO, yay, which saves about R800 on a booster pump. Still, given the fairly high TDS/EC, I wonder if a higher pressure might not be needed to force that water across a membrane?

Incidentally, I tested (pre calibration) the Oasis ozonated water available from the Oasis filtered water shop here, and it has an EC of about 8 - which will do for now. And at R4.50 for 5 litres, is a whole lot more affordable than R37.15 for 5l, or R13.75 for 1l that pharmaceutical grade distilled water costs!

Of course, I imagine that water and oil pressure gauges are not happy buddies, and I doubt that gauge will work again once its insides corrode...

Tuesday, January 18, 2011

Calibrating a Hanna HI 98129

A few posts ago, I talked about a combined pH and EC meter (Hanna HI 98129) I recently acquired from RS Components (who have an excellent overnight service on anything they have in stock - even to a backend Dorpie like Grahamstown)!

Of course, like any scientific instrument, it needs a baseline from which to work in order to ensure accuracy. For this, you need to calibrate your instrumentation. Some instruments drift a *lot* over time - so much so that they can become dangerously misleading if you rely on them and don't realise that the values can drift! So, in the interests of accurate readings, I ordered some calibration and storage solutions:

To calibrate pH, you need two solutions:
Hanna HI-7007/1L, a pH 7.01 buffer
Hanna HI-7004/1L a pH 4.01 buffer

To calibrate EC, you need one solution:
Hanna HI-7031, a solution with an EC of 1,413μS

Hanna recommend storing their pH electrodes in a particular storage solution,
Hanna HI-70300

I'm still waiting for the electrode cleaning solution,
Hanna HI-7061

Interestingly, these solutions cost about the same as the instrument itself... Science works, but the toys can get pricey, fast!

Here's a random shot of the calibration and storage solutions around the instrument which is sitting in pH 4.01 buffer. Note the pH had already drifted out by .01 in the time it took me to assemble the shot!
A few tips:
  • Make sure you rinse out the container you're doing the measurements a couple of times with the reagents you want to use for calibration (and ideally the instrument too) - this should remove any contamination which might affect the readings. This includes previous buffers and solutions!
  • When you do a two point pH calibration, don't rinse the electrode with pH 4.01 buffer, it assumes this is immersing it in the buffer - instead, add slightly more to the container you're doing the calibrations in and swish the instrument back and forth a couple of times. If you don't, I find the calibration goes waaaay out. 
  • When you're trying to do the EC calibration, you have to start in EC measurement mode (NOT pH) - the manual isn't explicit here, so I then ended up having to redo my pH calibration. Again.
  • Storing a pH sensor in the recommended solution is usually a good idea; the manual specifically warns against storing it dry (requiring a one hour rehydration in storage solution) or in distilled/tap water, which (I assume) causes the delicate ionic balance inside the electrode to go awry.  I'm storing mine with a few drops of the solution in the pH electrode "cup" inside the lid, standing upright in a glass, hopefully preventing leaks. The EC of this solution is higher than the measurement range of this instrument, so I'm not sure flooding the entire cap is a good idea. 
  • Ideally, calibrations should be performed at STP (Sea level, 25ºC), although these meters can theoretically cope with deviations from this as they have a temperature correction factor built in. Temperature affects both the pH of buffers and EC values of salt solutions (in fact the labels have the correct values at a range of temperatures printed on them). This evening, it was about 27 degrees in my house when I did this (and very humid!).

Monday, January 17, 2011

Sophrolaeliocattleya Kararizi Dawn 'Red Star'... or is it?

Our Sophrolaeliocattleya (Slc.) Kararizi Dawn 'Red Star' [bought from Exotic Plant Company (EPC)] has bloomed, with two gorgeous red flowers. Slc.  are intergeneric bybrids, with plants from the genera Sophronitis, Laelia and Cattleya in their ancestry. Wikipedia suggests there has been quite a bit of taxonomic upheaval in this group, and Slc. is probably not the correct name for many (if any) of them any more... I can't seem to find this particular hybrid in the RHS database either. :/ These plants apparently like fairly warm temperatures and quite a lot of light.
Slc. Kararizi Dawn 'Red Star'
Both flowers
Two more buds on their way - yay! Judging from how quickly the last flowers developed, they should open in about 2 weeks or less.
Close up of the labellum.
Interestingly, these flowers (and the others we saw already in bloom at EPC) are very red, with hardly any yellow and quite narrow petals; the "official" picture for this particular hybrid shows a lot of yellow, and much broader petals:
Slc. Kararizi Dawn 'Red Star'. Pic courtesy Exotic Plant Company.
I think I prefer the style of the ones we have to the "official" picture! It also seems possible that either EPC or their suppliers got the hybrid name a bit wrong; whilst googling Sophrolaeliocattleya, I came across something called Slc. Kagaribi Dawn 'Red Star'; this picture looks a lot more like ours! Also, the only google result for the name on the label is at the EPC website, whilst Kagaribi Dawn 'Red Star' gets quite a lot of hits. There is also an entry for Kagaribi Dawn (a hybrid of C. Kagaribi and C. Tropic Dawn - which are hybrids of hybrids too!) in the RHS database - looks like these plants are now considered to be Cattleya...!

There are more Orchids on Balconies...

I mentioned my balcony-based orchid growing habits to Johan Gauché from the EPOS, who kindly sent me some scans of an interesting article from the 2004 edition of the South African Orchid Council's publication, Orchids South Africa. The article is entitled "The Hanging Gardens of Melville" by James Sonnenberger.

Having moved from East London to Melville in Johannesburg in the mid 1990s (leaving his orchid collection behind) the author tells us of his reintroduction to orchid culture in his second floor flat through a request for a white Cattleya for a bridal bouquet at his florist business. Now he has a fairly diverse collection not only on his (semi-open) balcony, but on every available windowsill too!

It looks like the author is taking the challenges of balcony culture in his stride, harsh frosts aside, and is doing well in flower shows with his specimens. As our balcony is totally enclosed with windows and a small electric heater dispenses with any risk of frost, I suspect stifling summer heat, rather than winter cold will be our continued challenge!

Saturday, January 15, 2011

New Gadget: 40cm "Mist Fan"

A lot has been written about the importance of air movement and humidity for orchid culture. Our little balcony can get stiflingly hot during the day (indeed, by 8am it's often over 30ºC in there) and in January and particularly February, Grahamstown air temperatures can regularly reach into the 40s.

As much as I am tempted to demolish a wall/replace windows and install a massive fan in the other side or the balcony to get a wet wall evaporative greenhouse cooler up and running 1) it's very expensive 2) my landlord would have a fit 3) I suspect the Grahamstown Aesthetics Committee would object to the rather grievous alteration to a building from the 1800s! And a misting system would result in very wet floors (not to mention there's no water supply out there)...

A few weeks ago, I saw some "ultrasonic mist fans" in a shop. I decided that these might well help out, in that fans provide air movement, mist provides humidity and evaporating mist cools air. I ordered a Russel Hobbs 41cm Mist Fan from Makro online and it was delivered the other day.

After setting it up, I played with the various modes; it even has a "natural wind" function that varies the fan speed constantly. A very rudimentary trial suggests it cools the air by about one degree Celcius whilst the mister is on. The 1.5l water reservoir has to be refilled about three times a day, which is a bit of a pain. Another slight annoyance is that if there is a power cut (or you turn it off at the wall or via a timer etc) it resets itself to an "off" condition, which pretty much eliminates any hope for automation. :(

Until I receive my rather fancy LAN-enabled thermohygrometer (usually used for monitoring computer datacentres!), I'm not sure what it's doing to the humidity; I haven't been able to find even a basic hygrometer in town.

It's a bit too early to tell what the plants think of their new more "buoyant" environment, but I hope they like it...

New Gadget: Combo pH & EC meter

Yesterday I received a Hanna Instruments HI 98129 combo pH and EC meter. Grahamstown has a chequered history of water quality; debate has been raging over the last few years whether it's even fit for human consumption, let alone raising fish or fairly delicate plants like orchids.

Most orchids like their water to be slightly on the acidic side; a pH meter lets you see just how acidic or alkaline your water is.

Electrical conductivity of water gives you an approximation of the amount of salts dissolved in the water; pure water hardly conducts electricity at all, whilst water with a lot of salts and minerals in it conducts electricity quite well (which means you can use distilled water to put out electrical fires in server rooms, but spilling salt water on electronics usually results in them not ever working again). Most orchids are only ever watered by rainfall, which is pretty close to distilled water in its composition - hardly any mineral salts and a slightly acidic pH.

One generally expects that replicating the conditions orchids usually grow in in the wild will result in success at home; long experience has shown people that this is indeed the case.

There is of course another source of salts which we generally consider "good" for our plants - fertilisers, which are made up of various salts and minerals, which of course affect the composition of the water. Years of advice has suggested that fairly weak concentrations of fertilisers on a fairly frequent basis ("weakly, weekly") are the best bet for orchid cultivation. Too much fertiliser can be worse that too little (just as more orchids are killed by over-watering than drying out!).

I hauled the meter out of its box this morning and quickly did some tests. As I expected, Grahamstown water did not fare well:
Grahamstown Tapwater: pH 8.20, EC 669μS/cm  - quite alkaline and rather salty (for orchids).
Aquelle spring water: pH 7.2, EC 72  μS/cm - not too bad!
Distilled water: pH 7.05, EC 3μS/cm - pretty good, as you'd expect. 

Experience has shown that different kinds of orchids will tolerate different levels of dissolved salts in their water before it essentially has the same effect as you drinking seawater - i.e. it dehydrates you and is no good at all, despite your best intentions.

I found a reference on the Eastern Province Orchid Society's website which suggests the following thresholds:
400μS/cm: Cattleya, Paphiopedilum
600μS/cm: Odontoglossum, Coelogyne, Lycaste, Oncidium, Masdevallia, Miltonia
800μS/cm: Phalaenopsis, Cymbidium
That means that even without fertiliser added, Grahamstown tapwater is unsuitable for all but the most commonly and widely grown orchids (Phalaenopsis and Cymbidium). And I suspect Disa are real pansies and need a lot lower than that! Buying distilled water and/or spring water to water your plants seems a little excessive, so I'm going to test some other possible sources, particularly spring water. Given that we live in a rented second story flat, there isn't really any feasible way of harvesting rainwater, and Reverse Osmosis units require plumbing modifications, unfortunately!

Next I'll have to test the various fertilisers we use to see how they affect the conductivity and pH and just how much we should be using... I've also ordered some calibration and storage solutions for the meter to make sure it's accurate and stays that way!

Thursday, January 13, 2011


We bought some Paphiopedilums at Exotic Plant Company. Much like the Zygopetalum, they didn't have too much information beyond their Genus name. I've written to them asking if they might have additional details on these three plants, fingers crossed! (Edit: they did, have added names).

The more fancy looking of the two paphs looks like this, and was originally grown by PP Orchideeën in the Netherlands:

Paphiopedilum (Bagley x insigne)

The other one is showy in a rather elegant, understated way, with mottled green leaves and flowers striped with green:

Paphiopedilum Onyx

Note the stripy leaves.
Paphiopedilum are classed as "semi-terrestrial" orchids; their potting mixes are generally a little finer and more water-retentive than those for true epiphytes. They generally grow quite low down in forests, often in leaf litter, in fairly shaded habitats, so they prefer quite low light as a general rule. Apparently they're generally quite happy as houseplants, preferring similar temperatures to us!


Another of our Franschhoek acquisitions is a Zygopetalum. This orchid has a really strong scent of jasmine/gardenia, particularly early in the morning. Unfortunately, the labelling is not very informative as to its exact genetic makeup, as it only says Zygopetalum! This one comes from Lansbergen Orchideeën in the Netherlands by way of the Exotic Plant Company. The flowers are large and attractive too, as you can see below. Apparently, Zygopetalums can flower several times a year, which is an added bonus!

Zygopetalum flower

Orchids at La Motte

Aside from making some really great wines, including a firm favourite Sauvignon Blanc, La Motte has several flower-growing initiatives (and an impressive and picturesque lavender field for essential oil). They are most proud of their Disa growing, and if you ask nicely at the tasting room, the horticulturalist at La Motte (Neels van der Linde) will take you on a tour of their facilities.We managed to get on one of these tours whilst staying in Franschhoek recently.

We went through two different growing areas, one under shadecloth with a suspended misting/watering system, and another higher-tech polytunnel greenhouse.

Neels went through the history of La Motte's acquisition of a large Disa collection from Prof. Cywes, which was in serious danger of being repatriated to Japan, highlights of their natural history in the veldt and pollination and hybridisation.

The number of plants there is quite staggering, yet with the flowering period coming to an end Neels apologised for how "empty" the growing houses were!

Neels said that other than the odd fungal problem (which seems to be an inevitable hurdle in Disa culture) they had found culturing these "notoriously difficult" plants fairly easy - but modestly noted that if it were that easy then surely the horticulturists in the Netherlands would have got it by now - so they must be doing something right!

I asked Neels if it was OK to take a few pictures; I didn't know if they would be sensitive to potential "commercial espionage" (aquaculture facilities often go nuts if you pull out a camera!), but he was more than happy to have me wander around in the greenhouse snapping away.

The more sophisticated polytunnel greenhouse was quite amazing (and would cost several million rand to install, apparently); they have build a series of watertight benches which are occasionally flooded with water about half way up the pot from a ~500l tank below each the benches. Overhead, there are large blowers connected to polythene tubes with air holes along them, supplying fresh air, and of course, a large ventilation fan and wet wall to keep things cool, along with overhead misters. Neels pointed out that fungi are often water-borne, so this method of cultivation is not without risks; I immediately wondered if plumbing in some sort of UV steriliser or even using ozone to sterilise the reservoir water for a couple of hours a day might help... But compared to algae, fungal spores are pretty resistant.

Disas like to keep their roots cold and damp, so that system will certainly help - and it allows them to not sit around in water all the time, which is no doubt good for them. I stumbled across a website in America where someone improvised something vaguely similar for his Disas using a chest freezer to keep the water cool!

South Africa's most beautiful indigenous flower next to some Disas.
Disas. Many, Many Disas! Note the irrigation pipe for flooding the growing bench.
Yeah, you guessed it - Disas!
At the back there are all the new potential Disa crosses, neatly labelled with the mother plant's details, along with what was used to pollinate them.

On our way out of the farm, we bought 4 Disas from the shop at La Motte, robustly packaged in thick plastic gift bags, at the reasonable price of R75 each (picture of the last remaining flower to the left). And some extremely delicious baked goods. We've seen La Motte's Disas for sale at Woolworths too, and bought one last year, but the high heat in the car on the way back from PE (and during the shopping) took a toll the plant never really recovered from - and Disa Rot took it out shortly thereafter. :(

La Motte's recommended Disa culture notes are available on their website.