What's killing my dendrobium leaves?

[zuri]

I got this beautiful dendrobium in early August and bloomed for me for three months. But one by one, the leaves have been falling off. They start turning yellowish, with these spots all over them, and then die and fall off. I've only got one leaf left now. Here's a picture I took about a month ago. Does anyone know what's going on?

[articuno75]

I would have said it was just normal cycle die off had it been from the bottom of the cane, but this is located on the top. Do you mist your plant by chance? The spotting appears to be fungus.

[zuri]

Jenny, thanks for your reply. Nope, no misting, and I always water from the bottom so that no water ends up sitting on the leaves. The leaves started dropping in the heat of summer - high humidity, yes, but lots of heat too. The last one dropped about a weak ago - it's been cooler and drier. I think you're right about fungus... and so I'm wondering if it's the fungus that's killing the leaves, or if the fungus is populating after the leaf begins to die...

It doesn't seem like it's natural for a couple of reasons - because it's not just the bottom leaves that drop, like you mentioned, and because I now have only one leaf left - with no new growth. I've also wondered whether this could be the deciduous type of dendrobium... I lost the label for this one. I know it would be helpful to have it's name, but it seems like it started losing all of its leaves much to early for it to be the deciduous type. What do you think?

Thanks for sharing your orchid wisdom.

[11Orchid126]

How often do you water it? That type of dendrobium doesn't need to dry out. It likes to be watered regularly year round, watered well and then allowed to dry out. We need a little more information about it's culture.

[digitalgate]

It might be just shedding leaves. But how the roots? soft , hollow, dried? It might
not have enough sun light. Normally , leaves drop from the bottom up. Keep a look out
for pest.

[zuri]

Thanks for your input, 11Orchid and Digitalgate. I wish I hadn't lost the tag. I could try sending a picture of the flower to the greenhouse and see if they remember the name... and I'm also happy to take a few more pictures of it for you. The roots look fine, from what I can see. It's growing in orange, round pebbles... I thought it was lava rock, but the grower told me that it's a type of clay. When I water most of the visible roots turn green, but I can't see those underneath and haven't looked because the roots seem well-attached and the grower said it wouldn't need repotting 'til next year.

I've had it in south-facing shade (front porch)... it was getting a little morning light, maybe a couple of hours, and then bright, indirect light. Now it's inside in a south-facing window... but I'm afraid to put it near my other orchids because I don't want them to catch what it has... if it has something.

Please let me know if there's any other information I can provide.

11Orchid, when you said that it doesn't need to dry out... do you mean rest over winter? Or do you mean between waterings? In the summer I watered every three days, good, soaking waterings. Now that it's colder I water every 5-6 days.

Again, many thanks for all your responses.

[articuno75]

The plant is growing in Hydroton, clay pellets that are kiln fired to a certain temperature and retain a certain amount of moisture. These pellets are what a lot of growers use for Semi Hydroponics growing.

As for the leaves, the orchid doesn't appear to be nobile. I don't think it's decidious.

What 11Orchid126 was meaning is that this Dendrobium should not have a rest period or dry out completely from watering. This plant should be slightly damp by the time the next watering occurs.

My suggestion would be to keep the plant moist without drying out completely and water just when the medium gets slightly damp. Make sure that there is plenty of airflow on the plant to control fungal growth.

I hope this helps.

[brookn]

I agree with digital to look out for pests also. They like to hang out on the undersides of the leaves and in crevices.

[11Orchid126]

Jenny is right, the plant does not need a winter rest from watering, although it will not need as much water as in the spring and summer because of the lower light. When you say you water from the bottom, does that mean you pour the water over the pellets and then let it drain, or does it mean that you sit the pot in water and let the water be absorbed upward? If it's the second way, do you thoroughly flush the pot every fourth or fifth watering? Fertilizer salts can accummulate if this isn't done regularly, regardless of which way you water, but the second way allows more to accummulate faster.

Also, dendrobiums need lots of sun, as much as they can get, especially in the winter. If they don't get enough light, the roots will not be able to utilize the water and fertilizer and the plant will begin to suffer.

[zuri]

I have not seen any pests... though there's the occasional spider that likes to make its home here.

When I water, I pour water over the top of the pellets and wait for the water volume to build up enough so that the top pellets begin to float a little... and then I stop watering and it drains very quickly. I do not water my other orchids in this way... just this one, because the clay seems to dry out very quickly, and I want to be sure that it gets a good soaking when I do water it.

Over the summer I watered with fertilizer about every 3-5 waters, and then flushed with plain well water the next time. As its gotten colder I don't water with fertilizer very often... maybe 1 out of every 5 times. Do you think I need to water more often than every 5 days or so? I've never used this medium before - Hydroton, thanks Jenny.

I've noticed that my orchids in sphag take about a week to dry out. The house is 66-69 degrees during the day, and gets down into the low sixties during the evening.

It's in a south-facing window (which is shaded by a front porch), and gets enough light that when I put my hand over its one remaining leaf, there is a shadow. Not direct sun, but very bright.

Thanks to everyone for their input.

[articuno75]

I'm thinking too cool and damp for them. This can definitely lead to fungal issues. Make sure that the plants have ample airflow like a fan over the leaves to reduce the possible growth of spores.

[zuri]

Jenny,
Aww, I've been afraid that this is too cool for most of them. So - less water, and more heat. Any recommendations on how to increase temperatures without making a killer electric bill? I've got a spare bathroom with an east-facing window... perhaps I could make this my orchid room? Space heater? How do you all do it?

[articuno75]

Same amount of water. More heat and air. If you can find an area that can contain warmth with the right amount of light then all you'd need is a fan.

My apartment always hovers in the mid to high 70s. Sometimes the temps will spike in the low 80s and every once in a blue moon does the rooms go below upper 60s. I have a hard time controlling temps.

Humidity on the other hand.....All I can say is it's like the desert here in the winter.

[zuri]

I've got a fan on a few of my orchids (pointing upwards, so as to circulate the air but not blow them over)... guess it's time to buy more fans or put all of my orchids in the same room.

How to meet a variety of orchids' needs... this is something I've not known how to address. Seems like I have more or less one climate to offer, with very little subtleties. For instance, right next to the window is cooler than the center of the room; south-facing windows get more light than north-facing ones... How do you find or make microclimates in your house?

Thanks for all your help. I'm going to try increasing temperature and airflow and see if I can't encourage this dendrobium to keep its last leaf and perhaps put out a new cane at the same time.

[articuno75]

I keep all of my orchids near East facing windows, either on the rack or on a shelf. Some are closer to the window according to light requirements. I also have a small light that shines on those that need the extra wattage. I have an oscillating fan that blows on them.

Really the only one that I had to make a "micro climate" for was my Psygmorchis. I stuck it into one of those bowls that you get when you order soup from a Chinese restaurant (the large size ) I had to lay moss on the bottom and hang it in the middle. (it's on a mount.) It grows in Tolumnia like conditions, but humidity is really hard to keep up with this one. I keep the moss wet and I mist the leaves of the plant when needed. I found this to be the perfect solution.

[11Orchid126]

I would say that an east window would not be enough light for a dendrobium. A south or west window without shading would be much better. Dendrobiums need almost as much light as a cattleya. If you can grow a phal in the same light that you have a den, the den will suffer. Wherever you grow a cattleya would be the place to put a dendrobium.

[articuno75]

I've never had a problem growing my Catts or Dens in the East window. I grow my Oncidiums in the same spot too, and some of those take as much light as the requirements of a Catt.

They all do well.

[zuri]

The humidity is definitely higher in the bathroom (because there are so many plants in there, plus a fan blowing over a bowl of water), but the light is better in my office. What do you think is more important? Jenny, your east-facing window... is it due east? I'm afraid that mine leans toward north-east. There's good light, especially in the morning, but it's not terrific. Maybe I need to supplement with an artificial light... Jenny, how often do your plants rebloom for you?

[articuno75]

My windows are due east. All of my Oncidiums bloom on time and so far no problems. Same goes for the Neos with growing and following the schedule. I now have a few Dens that are getting ready to spike. A couple of Phals are too. Even the rescue Phal that I just saved over the summer.

Here are updated pics of my grow space. My Paphs and Vanda aren't seen cause the Paphs are on the lower rack and the Vanda is being soaked right now, LoL. But you can see in the pics that the windows and the light that I use. All of my plants are mixed together and received the same amount of light. The Black shelf you can see that there is a Catt in sheath and if you look carefully behind that very shelf is the Cyms that Solay sent me. (one of which is in spike)

Oh one more thing I forgot to mention. The oscillating fan is not in the picture, but it is beside the light just left of it, in front of the ottoman. It blows on the orchids 24/7.

[11Orchid126]

Zuri, light is far more important than humidity. In fact, light is the single most important thing in the culture of orchids.

[zuri]

11 Orchid, thanks for your reply. This is good to know. I'll keep my dendrobium and cattleyas in this south-facing window and add a fan.

Jenny, your growing space looks great! What kind of light do you use to supplement?

[articuno75]

It's just a CFL GE 1750 lumens 26 watt Energy Smart bulb (Those twisty looking ones )

[zuri]

Oh! I thought maybe I needed to get a special light... if a household one will do, I can have this setup in no time!

Thanks!

[zuri]

My den has now lost its last leaf. Just watered and some of the roots are still turning green. Have in a south-facing window with fan plus supplemental light.

Should I unpot to check on the roots? Or just wait and hope it makes a comeback?

[kmarch]

You have a phal-type dendrobium. Instrictions for its cultureal requirements can be found on the Dendrobium culture sheet offered by the AOS at AOS | Home

[davetheorchidaddict]

Jenny grows in east window and has no problem, I love to do things that I have been told could not be done and succeed most of the time. I had a lot of problems with Phal gigantea untill I mounted it and gave it Cat light. I always remember the Bumble bee which aerodynamicly unable to fly but it does not know it cannot fly and flies all over the place, I try to be a bumble bee. I grow orchids on the bottom of inverted clay pots but was told I could not do it. Glad you are a bumble bee Jenny.

[kid a]

I grow under lights in my bedroom and I use 13 watt full spectrum ("daylight" on the package) compact fluorescent twisty bulbs. So far I've had great results reblooming with them. I also have a west facing window and north facing window which open the blinds on during the day but most of the light comes from the bulbs. I use desk lamps since I don't have many plants.