DISA CULTURE

Pots:   I used to use and recommend 6" net baskets for mature plants. The plants seem to grow better and develop more offshoots than any other method. I still use them for some species, especially cardinalis but  as of July, 2001, I have started using a new pot that I have come across.  While the big plants do well in the 5 x5 x6 pots, I have noticed that those pots are a bit too large for some of the hybrids.  I came across a pot called a 450 tagloc and it is available from Dillen, Kord and ITML.  It is 4-3/16" square by  4-7/8" deep. It comes in a clay color and I will be trying it for small adult sized tubers when I repot this fall.  One additional note about convenience.  It's a good idea if you can get trays for the pots so they don't go all over the place when you bump the shelf. They also hold the pots at an even depth when you put them in a flow table. You can see a picture of the pots on the supplies page.

Repotting:  There is now a separate page devoted to repotting and for an illustrated step-by-step description of the process, you should see the Repotting page.  A brief outline is presented here.  There are a couple of rules about repotting. The first rule is to repot when your plant doesn't look good.  Don't worry about throwing off the spike cycle or anything like that.  If your plant looks like it has a problem, take it out of the pot and carefully check it out.  Usually you will find root problems this way.  You can then remove the dead and/ or decaying material,  treat it with a dilute fungicide, and pot it up. I usually hit the problem area with a very hard spray of water using maximum hose pressure through a 4 gal/minute Fogg-It nozzle. This won't hurt any good healthy material but washes away some of the decaying material.  You have to support the plant a bit though when you do this or it will take the roots right off.  I use a piece of plastic fly screen or window screen in a frame that exactly fits the sink.
        The second rule is to repot at least once a year.  The optimal time is after blooming but before the middle of Winter.  I used to let this go longer but there is a good reason for separating the new plant from it's old decaying parent.  The longer the plant sits and soaks up sunlight in the winter, the better the tuber and the stronger the flower spike the following year.  In the northern hemisphere, you should be finished repotting by Christmas.  You don't necessarily want to do it the minute that the bloom is finished but there should definitely be new growth starting.  If I can't see next year's growth, I put the plant to the side and leave it for the last batch to be repotted.  Usually by then something will happen.  If it still doesn't have any new growth, you can take it out and look at the roots, but you probably have lost the plant.  This kind of goes back to rule one.  If you have a blooming plant with no new growth that isn't just a second year plant that has never made a tuber, you might want to tip the plant out of the pot and see why no new growth is being formed. 

Pests and Problems - An Overview  This is another long and involved topic.  Sometimes you don't even know that you have a problem until a significant amount of damage has occurred.  The best way to become aware of problems is to examine your plants on a regular schedule.  This is easy when they are in bloom but the other nine months are just as important.  Try and make a habit of looking at your plants at least once a week.  This is easy when you hand water but needs to be done even when you bottom water.
    There is another aspect of dealing with pests that you need to decide about.  If you have Disas, you are going to be stuck using fungicides and insecticides to control problems.  I don't like to use chemicals mainly because as a former chemist, I have a very healthy respect for organic chemicals.  I have had to overcome my personal bias against the use of chemicals, and once I did, I have noticed a definite improvement in my plants' appearance.  I basically advocate a prophylactic approach where you don't let problems build, but spray the whole greenhouse or growing area as soon as you notice a single problem.  This goes for insects, fungi, or snails/slugs.   But don't apply chemicals without protection!  I always have all skin covered and use an Army surplus gas mask with the appropriate organic cartridge.  Don't forget to turn off your fans when you are spraying.
    I find that I'm using a few compounds that seem to work reasonably well under my circumstances.  My first  tool is a mixture of Knox-Out and Orthene WP.  Knox-out is a microencapsulated Diazinon insecticide and Orthene WP is a broad range systemic insecticide.  They mix well together if you use a little liquid soap as a sticker.  The idea is that the Knox Out is effective for up to a week and by then the systemic function of Orthene is taking effect.

    In general, the following chemicals have worked with Disas: Orthene WP, Malathion, Knox-Out, Mesurol WP, Banrot, Clearys 3336, Dithane 45, Subdue, and Captan.  I have also been using a new/old tool in my battle with fungus.  As most orchid folks know, powdered sulfur and cinnamon are two common items found around the house that act as fungicides.  Well, powdered sulfur doesn't do much against this particular fungus I've had to fight lately,  but cinnamon seems like it may have a beneficial effect.  I have been using it where the fungal infection is in the center of the plant and therefore not able to be cut out.  It seems like when cinnamon is used, the new leaves grow right thru the cinnamon and are unaffected by the fungus which appears to dry up.
    Be careful with Physan 20, and Neem oil.  They seem to damage the plants. I continue to use Physan 20 with my deflasked seedlings but at very low dosage (about 10 drops / gallon) and I wash it off after potting.

Some of the problems that you need to look for include:

Temperature  Disas are very forgiving.  They will grow and survive hot spells of over 100 degrees F and also the occasional frost. The Summer of 2000 started off in my area with a couple of days where the temperature got to 100.  Unfortunately one of those days corresponded with a day that I was away from home and in which I also had a power outage which blew my circuit breakers.  I arrived home that night and discovered some of the leaves and virtually all the early flowers and flower spikes severely wilted.  I sprayed everything down with water and turned on the misters for a while and by the next morning the plants and spikes looked better but most of the flowers were damaged.  The high/low recording thermometer that I keep at pot level recorded a high of 118 degrees Fahrenheit.  I have usually had summer temperatures in the 90's in the greenhouse but the high pressure mister has so far kept the temperatures under 100 when it has been working. 
        On the other side of the temperature range, Disas will survive an occasional frost and even short periods of temperatures below freezing.  I have been a bit chicken about subjecting my Disas to this low a temperature because I have some other orchids housed with them.   However, both the New Zealand growers and Wally Orchard who is up in Olympia Washington have had experience with frosts and even snow on the Disas and claim they come through unscathed.  This doesn't mean that they can be left in sub freezing temperatures for days on end but that they can take an occasional overnight frost.  If you have conditions where the tuber is frozen, you will probably loose the plant.
        The root temperature is reputedly another area of concern.  Since I live in an area that has some Ocean influence, Sunset designates this area as Zone 14 - moist, I always have a quite marked drop in temperature at night. This nightly temperature drop allows the Disas to recoup from any daytime temperature stress and also keeps the overall root temperature low.  It is not uncommon for the summer nighttime  temperature to get to the 50's.  As a result, I don't usually have to worry about root temperature and don't often monitor it.  For those of you who live in an area where the nighttime temperature stays high, root temperature might be a problem.  While I don't have any hard scientific data, a number of South African growers carefully monitor root temperature and claim that any prolonged periods of root temperature above 70 degrees F will cause problems.  This might be overcome by using unglazed ceramic pots  but I don't have any personal experience.
        The last area that I want to discuss is the difference between day and night temperature.  Disas definitely like cool temperatures and in nature experience a wide variation between day and night temperatures.  They are cooled at night and often partially shaded during the day.  Ideally, they probably do best in the range from 40 to 75 degrees F.  In talking to people who try to grow Disas under relatively stable conditions like a basement, unless you can get a 20 degree temperature swing between day and night, you will probably experience difficulty. 

Fertilizer:    This is where it is easy to kill Disas.  Only the most dilute solutions should be used.  If the TDS of the fertilizer solution is above about 300 ppm, there surely will be some problems with the plants.  I only fertilize during spring and early summer.  After the flower spike is close to maturity, I discontinue feeding until the next spring.  Different people have different ideas about when you should fertilize.  Most agree that you shouldn't fertilize during  winter.  I've testing the idea that Disas don't really need fertilizer to grow.  One of my smaller flow trays contained water that was not supplemented in any way.  It didn't work very well.  I've gone back to supplementing all the plants with a very weak fertilizer solution during their growth period.  Try and keep the total TDS to between 150 and 250 ppm.

Micronutrients:  I have tried experimenting with the addition of Micronutrients and especially iron but can't honestly say I can tell the difference.  I do add Epsom salts and iron to my fertilizer solution though during the time of year that I fertilize.  After trying to do without micro nutrients for a year, I have decided that the plants seem to do better when I do provide micronutrients.

Humidity:  Some say Disas will grow where it is dry and some say humidity is important for good culture.  Some of the best Disas I have ever seen (besides mine) grow within spiting distance of the Pacific Ocean. ( I try not to think bout how much salt is in the air.) I seem to find that they tolerate high temperatures better when the humidity is high. In fact, I cool my greenhouse by the use of a high pressure misting system.  Works well.

Light    Disas will take full sun but I think the best results at least for hybrids are obtained with bright Cattleya light with cool Masdevallia temperatures. The problem with high light is there is also heat associated with the light.  If you can provide high light without the increase in temperature, then the Disas will appreciate it.  The number of hours of light must also vary between summer and winter.  Those who live too close to the equator will probably not have much success with Disas.  The evergreen species and the deciduous species need more light to bloom.  They definitely are used to full sun.

Air    Good air circulation is a most with Disas.  If you can't keep them outside in a shade house, you must have good fans to keep the air "buoyant". This is probably the main problem with trying to grow Disas in a room under lights.

Numbers  Lastly, a person that wants to try Disas should never start with just one plant. I don't know why, but Disa culture is so imperfectly understood, that you can provide ideal conditions to a group of 10 plants and you will see 4 of the plants just grow like crazy  while 5 will just kind of sit there and grow slowly and the one remaining will die. If you are doing everything right, the 4 plants that grow like crazy will put out 10 - 15 offshoots by the end of the year so you will still have increased your population but if you just start with one, for sure it will be the one in 10 that was going to die no matter what you did to it.  I know this sounds a bit off the wall, but I'm really serious when I say that you need to start with a small population and not just a single plant. 

When All else fails, listen to your plants!