Mold in my S/H!!

[Des]

That white line you have can be a build up of salts . So you might have to use less fertilizer. I fertilize every time I water , but at a lower rate this seems to help/

[Pals]

Originally Posted by Des

That white line you have can be a build up of salts . So you might have to use less fertilizer. I fertilize every time I water , but at a lower rate this seems to help/

Many thanks for your view Des, but I'm sure it's not salts from fertiliser, people talk about fertilising their orchids weakly weekly or every other week or even monthly.
I can talk about fertilising mine in six month stints minimum (yes, my head is hung in shame as it should be ) which makes me believe it's just a manifestation of whatever goes into the pot, harmless or harmful. Water may go in sparkling clean but think what that media must be like after 6 months or 1 year!

Pals

[Des]

Just a thought, some years ago I bought some hand made clay pots to plant miltoniopsis , the plants took an instant dislike to these pots and i soon noticed a white powder covering the outside of the pot. It turned out that the person making these pots mined the clay from a dry river bed very close to a salt works !!!. So your problem could be the pot!

[Oldguypops]

Here are some pictures of what I have on my pots. As you can see in the third picture, I am able to wipe it off with my finger.
It sure looks like mildew or mold to me.

Any thoughts??

[calvin_orchidL]

Originally Posted by Oldguypops

Here are some pictures of what I have on my pots. As you can see in the third picture, I am able to wipe it off with my finger.
It sure looks like mildew or mold to me.

Any thoughts??

I have a similar thing happening to a certain set of pots I bought. When kept constantly moist, these pots develop the whitish stuff on it, and sometimes it turns green as well. It also doesn't smell too great. I have a feeling it's to do with the pot - I think some pots when fired are done so a certain way, or perhaps there is something put into the clay to discourage algal/mold/mildew whatever growth. Pots that don't get the treatment end up looking like this. I water all my plants the same way, and fertilize the same way, and yet only the plants in one particular set of pots gets this affliction.

[Pals]

Morning Guys!

These marks could be caused by a number of things but without an in-depth labratory analysis, I guess we'll never really know exactly what it is and although I didn't agree with Des' fertiliser suggestion I still strongly believe he, (like Calvin) is right in that its a chemical reaction not an organic one (mold).
I suppose in the final analysis, our plants can give us enough problems without looking for them, those marks have been around for as long as terra cotta pots have. The plant will tell you if something is wrong, until then why look for problems which may not exist.
I found a couple of articles, extracts reproduced below (hope I don't get nabbed for copyright!), one is from a professional potter, the other a University horticultural lecturer:

"Earthenware pots are quite porus, and, in addition, if they are from an Asiatic source the clay may not have been properly washed/prepared and may contain various salts that may react with your plants as they leach out from watering, especially if the water you are using is rainwater,which tends to be mildly acidic! (Similar to efflorescence you get on some brickwork, it looks like a white powdery coating)!"

"Unglazed clay containers are popular, but can be heavy and also tend to accumulate unsightly salt residue as water evaporates from the surface. This residue is generally not harmful to the plant, unless it accumulates in the soil"

Unfortunately the second extract doesn't hint where the salt residue originates from, the water or the pot and although they may or may not have the answer, both suggest it is still a chemical rather than organic reaction.

I suppose you could always move your collection over to plastic pots Chris?

Pals

[Oldguypops]

Thanks for the research Pals.

I put all of my orchids in the clay because I am a "waterer", but I have just ordered some clear plastic replacements. I will eventually repot everything into the plastic, and will, I believe, solve the problem.

After closer inspection last night, I noticed that it happened on 3/4 of my pots, but not all, lending credence to the "poor clay" theory. The more expensive clay 'orchid' pots are clean.

Thanks to all who responded.