We need a few more details to give you good advice. Is it potted or mounted? What sort of medium, if any? This species likes to stay evenly moist, moderate temps and light -- is it in a windowsill, terrarium, or greenhouse?

Dilute fertilizer should not cause the symptoms you're describing. Poor water quality, however, might...as will imbalances in other conditions mentioned above.

-Bruce C.

The fertilizer (1-0-1) is intended for use with distilled, or RO water. My laevifolium is in a south-facing window with supplemental lighting. It does not get any direct sunlight - the light levels are medium. It's in a plastic pot, the medium consists of fir chips, sponge rock, and maybe a little charcoal. In the time I have had it, it's never been given any water except distilled water. I don't let the medium dry out, if anything I may have had too heavy a hand with the watering. It does not appear to be suffering otherwise - there are new roots forming and two pseudobulbs with new leaves. Perhaps I am overwatering or the medium has become sour.

Mike

I would say it would be next-to-impossible to experience leaf-burn with 1-0-1 and distilled water. Mine is in green-growth phase at the moment -- should I assume that the yellowing you're describing is on new growth? If that's the case, it may be wet leaves as a result of watering/misting. How's your air movement? You don't have to see a visible drop of water on the leaves for there to be a problem, which occurs usually at night.

If the leaves are on older pseudobulbs, then it is potentially more complicated.

It's entirely possible that the fertilizer you've been using isn't intended to be the only type of food used for orchids, but as a supplement. 1-0-1 sounds a bit light to me. "P" is just as important as "N" and "K". Does it have micronutrients? I've heard that as bark decomposes the microfauna in the organic components use up available nitrogen, although I've never read any convincing studies other than conjecture. Still, it may have relevance in a small pot.

Watering can be especially challenging for indoor orchid hobbyists, particularly for more "persnickety" species. It's possible you are too wet. Factors here are plastic versus clay, pot diameter for size of plant, mix, and drainage.

Are the roots attached to the sides of the plastic pot? If not, carefully lift it out part-way so you can get a look inside. Is the medium *wet* around the bottom? Is it drying out properly near the top, yet staying wet near the bottom? Then adjustments are necessary. Moving to clay might solve your issues, as will a couple well-placed styrofoam peanuts.

Is the pot size too large? A Den. laevifolium with 5-8 growths would be properly-sized in a two to three-inch pot depending upon evaporation and mix.

Depending upon temps, air movement, and drainage, plus your individual watering habits, one type of mix may perform better for you than another. One problem some hobbyists have is owning many different types of orchids in different-sized pots with different medium types. This complicates watering, and it's not uncommon to have rot issues as a result. With your description of the mix it's in, it would take years for it to become "sour", and then only if you had poor-quality water. If you've over-watered, it's possible that it has degraded near the bottom of the pot. Again, this is where the visual check would be helpful.

Many people hate sphagnum, but it's my favorite medium. When providing proper drainage and pot size, it's almost impossible for it to stay too wet for long, and instead achieves that perfect "evenly moist" condition where roots do best. I nearly always use it on my mounts, and my laevifolium is quite happy wrapped in a sphagnum pad on a cork mount. Sphagnum works equally-well for me in plastic pots.

Yet another problem indoor-growers have is air movement. Is there adequate room underneath the pot for air penetration through the drainage holes? If not, set it on a "mini-bench", such as a wire shelf-rack from WalMart. Another solution would be to bend a small wire hook to suspend the pot by hanging it on something. A small fan, if you don't use one already, will help circulate air better, as well as help dry leaves off.

Given what you've described, I think your plant is too wet, and perhaps is suffering a bit from lack of nutrients. An occasional application of richer fertilizer will go far in making a plant better able to withstand stresses, when conditions are temporarily less than perfect. It doesn't have to be an expensive fertilizer either. I have tremendous success using the 7-7-7 MiracleGro African Violet Food, which costs about $2.25 at WalMart for an 8 ounce bottle. At half-strength, this makes 32 gallons. I also use seaweed perhaps four times per season.

Any one of the issues I've mentioned above, or a combination of them, could be the culprit.

Hope this helps.

-Bruce

Hi, Mike and Bruce,

Bruce - If a plant's sitting on the grid on top of a standard plastic drip tray, does it have enough air circulation underneath, provided air's moving in the room? There's little to no water in the drip tray.

Thanks, Whitecat8

Hi Whitecat8 --

Probably not, although there are other factors involved as well. How large are the airholes, is the mix prone to staying wet in the first place, is the pot sized correctly to the plant, etc.

The issue is not oxygen to the roots via vigorous air circulation. The purpose of air circulation underneath is to control the moisture level in the bottom of the pot(s), as the bottom third is potentially the most problematic. If you're watering correctly to maintain the optimal moisture content near the base of the plant where it contacts the mix, you want to try to have the rest of the volume of the pot as close to that moisture level for as long as possible. In practice, that never happens, but that's the goal, anyway.

It's not necessary to have lots of air movement underneath your pots if your watering habits, drainage, medium type, etc., don't result in prolonged wetness.

There are sometimes debates about humidity here on the Forum, but this is one situation where high humidity can be beneficial. (High humidity is ALWAYS good, but can cause problems especially indoors.) The higher the humidity, the slower the evaporation (somewhat irrespective of air movement), the longer a "perfect" moisture can be maintained at the roots between waterings, and less likely for other problems to occur as a result of increased watering schedules.

-Bruce

Hi Bruce, this is definitely helpful, thank you for your insightful responses. I will try to answer your questions.

The yellowing/browning I am describing is not on the new growth. The clump I have has about 4 old leafless pseudo bulbs, and two mature pseudo bulbs with leaves (these are the ones with the problems at the leaf tips - one leaf on each pb respectively), and there are two new growths with emerging leaves.

Air movement seems to be good - I have a small fan in the window. At the level that the Den laevifolium is at the air movement could perhaps be stronger, but I think the air in the room and at this window shifts quite a bit because there is a cross-breeze due to other nearby windows.

The fertilizer I have may not be sufficient as the sole fertilizer. I think it does contain micro-nutrients (it's Green Jungle orchid food).

My laevifolium is in a 2" plastic pot. The pot is also squarish, with a square bottom. I have found with other plants that sometimes square pots don't drain as well as round ones that taper toward the bottom, but I have not yet looked inside this particular pot. And I'm not sure yet whether the roots are attached to the sides of the pot, but I will try to figure that out when I get home this evening.

It's funny that you say many people hate sphagnum, because I have recently been very happy with it and finding it the most useful option both for orchids that I have moved over to sphag from fir chips, and for other small tropical epiphytes that I grow. I would be interested to know how much sphagnum moss you used to pot your laevifolium and how densely you have it packed around the roots.

I think you are probably correct that the pot is staying too wet at the bottom. I will have a look tonight when I get home and I will let you know what I find.

Thanks again for your help.

Cheers,
Mike

Mine is perhaps about the same size as yours, although all of the pseudobulbs have leaves, and there are presently three new growths. It's on a cork slab, about 5" x 8" in size, with maybe a half-cup's worth of sphagnum around the roots held in place with monofilament line. It's hanging on my "cool wall" with my angraecoids, although at the moment my exhaust fan is in its death-throes (new one should be here next week) and daily temps in that microclimate are in the low 90s...about ten degrees higher than they should be.

I haven't seen an older specimen, but I imagine they should retain leaves for at least three or four seasons, maybe more.

I found an interesting discussion of MSU Fertilizer versus Green Jungle Orchid Food, linked below. There are many species of orchids that absolutely require nearly pure water, and therefore careful fertilization with perhaps special formulations, but I wouldn't categorize Den. laevifolium in that group.

On a scale of 1 to 10, with a "1" being the water quality a hard cane Home Depot dendrobium hybrid would tolerate, and a "10" being the water quality required for disas, Den. cuthbertsonii, and Andean masdevallias, I would rate laevifolium about a "6" or "7".

-Bruce

Here is a link that might be useful: MSU vs. Green Jungle

Hello Bruce and Mike,

Mine has been doing a similar thing except with new growth. You are right about too wet at the bottom. I keep it with others in a drip tray that I keep water in and if the water level is too high it just wicks right into the bottom of the pots !! It also seals off the air to the bottom of the pots !! I've found that my Maxillarias like being wetter than others, but most don't.

Thanks for the help !!

Chryss

Last night I looked inside the pot, and although the roots looked good, the medium was very wet. I had thought the medium was draining off faster than it is. For now I am going to conclude that I just need to water a bit less frequently.

Thanks Bruce for all of your help and advice.

Cheers,
Mike