New Dendrobium Mold and Spots

[akorchid]

Hello! I'm new here. I've been looking around for some answers for my dendrobium. I've tried visiting nurseries, but sadly no on is very knowledable or is willing to give me tips.

It has two main problems: moldy bark and black spots under the leaves

I've heard the suggestion to repot, but it's still flowering and I've only had it a couple weeks. I've tried diluted soapy water. It seems there might be very, very small white bugs occasionally on the bark. I'm not sure if it's getting enough air circulation, but I'm afraid to repot it fully into the perforated pot right now.

Also, I've found some small black spots on the bottom and the base of my leaves. I'm not sure if it's a fungus, or what.

Here are some pictures:



As you can see it's still in the store pot, set in another perforated one.
I am going to get a grow light too. Anything in particular I should avoid?

Thanks so much!

[Royal]

You'll get lots of info here. I'm no expert, but I'll pitch in my .

From your pics it seems like it's doing ok. I'd let dry out completely before watering again. I am really wary of the potting medium in grocery store orchids. The roots could be rotting away, and if you wait untill the blooms drop it may be too late. On the other hand, the roots may be fine, but neglect at the store could have conditions looking a little bad.

Check to see if there is a combo of two different types of media. The bark you see might look fine, but there might be soggy rockwool underneath or some other medium that never was removed before repotting! It depends on the supplier.

If things look bad -- repot. You may loose a few blooms but you'll save the plant.

If things are under control (thanks to you ), wait until the blooms drop, then repot. Just don't oversize the pot. These guys like to be rootbound.

Good luck, and good growing!

[akorchid]

Thanks for your help!

Another quick question: What type of grow light show I get? I'm going to a Home Depot...Could I find a suitable one there?

I'm happy I'm actually keeping an orchid alive!

[Royal]

There is a LOT of info on growing under lights here. I think there is a forum dedicated to that topic. Again, I'm no expert, but here goes.

It depends somewhat on the type of orchids you plan on growing. Fluorescent will do, but with a few things in mind. They don't put out a huge amount of light, and the intensity drops dramatically as you go away from the bulbs. Also, the type or color of bulb matters. Look for 5000 K on the packaging. Some will say 6500 K, and the "full spectrum" grow bulbs will say something like 3500 K.

Now that I'm trying to explain this - my ignorance is coming through.

High Intensity Discharge lights put out a lot more light. You could really grow some plants with one of these, but they get hotter, and are less available.

[Ross]

I guess I'll contribute as well. If it were my plant I would not risk the whole plant for one bloom season (there will be many more to come if you get on top of that wetness). The pot is way too wet. Plane and simple. The mold you are seeing would never occur in properly watered medium. I am sure it was the fault of the store, they rarely know what they are doing, unless the place specializes in orchids. My plan of attack would be to repot into large bark mix that has large charcoal in it as well. The charcoal will help with funky stuff that may hang around. When I got the plant out of that mix, I would tease away all the old bark and trim any old brown mushy roots. I would then spray liberally with either Physan 20 or Thiomyl, depending on any rot I saw starting. I would leave the plant overnight to dry out. I would repot next morning into bark mix that had soaked overnight in KLN mix (1 tsp per gallon RO water). I would then brace up the plant with some staking and then pour the rest of the KLN mix through the pot. I would then place it in a bright location out of sun. This is just what I would do - not what I am saying you should do.

As for lights, I use primarily t5 florescent strip lights (48") in a 4-tube fixture, but I also use compact florescents from this source 2 to 200 Watt Compact Fluorescent Bulbs : 1000Bulbs.com The Light Bulb Superstore. I use both the 55 watt and the 105 watt, and believe me they will turn Encyclia and Cat leaves purple! That means really high light. Here's my setup with the lights all burning (in a south-facing window)

[Royal]

Ross, I've looked for those locally, but the largest I found was a 35 watt. Would this do? Also, what does the "mogul base" mean? Does yours screw in to a normal fixture?

[Ross]

The mogul base is the larger one of the "old days" used for really big incandescent bulbs. No it won't fit. But the 105 watt does fit (I know because I use it). You won't find anything really useful at HD or local stores (I think.) The web site I recommended ships quickly and is really good. Be sure to select the "full spectrum" version of any CF you get because it will have both the reddish end and blueish end of the spectrum that you need.

[akorchid]

Hello again. It took me a long time to find a store that carried such lights too. I first tried browsing gardening, but found better results when I used keywords such as indoor sun, hydroponics, grow lights. I found a place that has a reflector with a clip, cord and bulb setup for 20$. I didn't go for a 55Watt, as it would protrude from the reflector, losing some of the effective lumens. I have my orchid set between a window with the blinds partially drawn and the light, clipped above and set very closely to the orchid.

Here's the link for what I'm using.
30 Watt Top Spiral

Here are links from 1001 bulbs that have more information:
Compact Fluorescent - 30 Watt - Full Spectrum 5000K - Wide Spring - Energy Miser FE-US-30W-50 Light Bulb
Compact Fluorescent - 55 Watt - Warm White 2700K - Energy Miser #FE-US-55W-27 Light Bulb