Ascocentrum pumilum light levels

Used to grow it in my old GH; I don't think it ever got full sun. It will grow and bloom in shade.

 

I have that one in my paludarium...the flourescent light levels don't really translate into actual sunlight levels...in my paludarium it's near the top so it gets the brighter light- but that would certainly not be anything close to full sun, so maybe I'd call it "bright indirect light" in terms of sunlight?

On another note, although I'm still a noob to orchids (only been growing about 1 year), wouldn't leaf drop typically be caused by other environmental conditions and not necessarily light levels? I thought watering, temps, and humidity are more likely culprits for leaf drop?

 

Stephen, what temps are you growing it in, night and day?

I just looked at my A. pumilum and noticed that several of the lower leaves are yellowing...but it does have 2 bloom spikes forming currently- I hope the spikes don't blast! It seems to be a slow grower and these spikes have been developing for months and aren't even in bud yet!

I've noticed that mine drops the oldest leaves as each new leaf is grown, which I am not sure is normal behavior for this species or not. I've seen some pics of these plants where they have a lot of leaves...certainly nothing like mine....and it leads me to believe that this is related to temps as you mentioned...I'd imagine if no conditions have changed and it's been a decent period of time, the plant indeed is wishing it had a cooler and/or drier rest period (but what does a 1 yr noob grower know anyway )

Aside from the leaf drop your plant is experiencing, does it in general have a lot of leaves, or not? Mine has max 6 leaves at one time.

I think my plant probably gets near, or even occasionally above the Andy's temp range listed for it... 52-80max. I've measured 80+ in my paludarium at times, near the top, but I don't know how accurate my thermometer was, and it's hard to get consistent readings in the tank..normal high is probably closer to high 70's..and min temp is probably 68 at night. I was a noob at the time I ordered this plant, it was my first orchid order ever, and I didn't expect my temps to be that warm, nor did I really understand the temp ratings at that time...if I knew what I do now, I probably wouldn't have ordered this species..Andy's says I/C, and grow well outdoors up to first frost, LOL, nothing like my tank.

 

Howdy. I've been gone from the board for a long time for lots of reasons, but came across this post and I have one that seems to be doing well. I hope it's not too late.

I got mine from Andy at the 2009 POE. I think it had 7 or so leaves at the time. It has bloomed every fall since and now has ~19 leaves on the original stem, 4 new inflorescences, and two new growths at the base with 3 and 4 leaves. So it isn't necessarily slow growing or limited in the number of leaves it can carry. As a guess, I'd say it has probably dropped 3 of the oldest leaves in the time I've had it.

I keep it in a glass case with good air circulation from fans. It is in a south facing bay window so it gets fairly bright filtered light throughout the day supplemented morning and evening by 4 T5HO tubes (mostly in winter when my east SF Bay location is often very dreary). At times when it has gotten more direct sun it has developed some red pigment around the edges of the leaves, but I did not notice that it's growth suffered at all. Temps range from winter night lows around 50°F to summer day highs of upper 70's to mid 80's, always with a 15-20° day-night difference. Humidity ranges from ~70-85%RH (mostly 75-80). Daily watering in summer, every 2-3 days in winter. Most summer water contains 2.5 ml (~0.5 tsp)/gal Dyna-Gro Orchid-Pro (7-8-6) with pH adjusted to ~6.2 with Dyna-Gro Pro-Tekt (0.0-1.5 ml with my tap water, which is low in dissolved solids).

From my experience with a single clone of this species it doesn't seem like your temps should be a problem and I don't think low light would cause leaf drop. But, you can't really consider one condition exclusive of all the rest. Mid 80's may be fine with good airflow and high humidity, but not at all if other conditions are off. Like Marni said, how are the roots? Do the leaves show signs of dehydration? No sign of rot (hopefully!)? There should be active root and leaf growth at this time. I try to use cultural descriptions as a place to start and then let the plant tell me what it wants.

Anyway, I hope this helps.

 

Stephen, somehow I missed this threat. My personal experience not as long, my plant has only 2 growths with 4 spikes developing during months and months and still far from blooming. However, based on Bakers' data looks like for you humidity is a critical point. Recommend level is from 80 up to almost 90 per cent. Unachievable in open environment of the light shelf. Say, it can grow at 70 per cent. This level is still impossible and dangerous (mould growth) to keep at home.