I think the orchid compost is going mouldy

[supersheep]

Please help! I think some of the chips in the medium are going mouldy!

I repotted two new phals in fresh media on Sunday, and I've not watered them since!

I used brand new, Orchid Focus media which was recommend on the internet, and one brand new orchid pot and one cleaned out with disinfectant. I even cleaned the ceramic pots I keep the plastic pots in and the stones at the base in disinfectant.

I removed all the rotten roots from the phals with sterlised scissors and left them for about 20 minutes in 3% H2O2, so I don't understand how the mould has gotten in, or grown so much!

I only watered them on the Sunday after repotting and left them both to drain!

It's been less than a week and the rooms about room temperature and if anything, the humidity is low because we have the central heating on a lot at the moment!

I'm starting to despair! I don't understand what went wrong so quickly and what I can do now! We can't get Physan 20 in the UK (it's banned apparently) and the H2O2 I can only get in small bottles - so they're not really practical!

Please help! I've become such an orchid-aholic, but I seem to keep killing them, usually because of over-watering, but in this case, I've only watered them on the day I repot them!

[Tim C.]

The first picture is difficult to make out, so I can't say for sure what's going on there. The second picture is a little rough, too, but I can see some good looking roots, and below them appears to be some mold/fungi growing - little white dots on what appear to be some old roots, which are black.

I am not familiar with the mix you mentioned, so I Googled it, and found that it's made with a mix of coconut husk chips and fir bark. CHC (coconut husk chips) retains a LOT of moisture. Couple that with a plastic pot, and it may be that your mix is retaining too much moisture, even for a Phal. I say "may be" in speculation, so definitely correct me if I'm wrong.

Stick your finger in the mix in each of your pots; is it moist, and if so, how moist? If you watered these plants this past Sunday, I'd expect the mix to be dry or close to it by now.

That being said, mold and fungi appear when there's too much moisture and too little air flow. You might try using clay pots with the same bark/CHC mix, or you might try to find a more open mix to use.

I grow indoors, too, and use a custom bark mix of small/medium grade fir bark, perlite, and horticultural grade charcoal. If I soak my plants today, they'll be needing another watering in about 5 days, give or take. That seems about average to me.

You also mentioned that you have the plastic pots sitting in ceramic pots. Do these ceramic pots have holes in the bottoms or sides? If not, then that could also be a problem, as they're not allowing your orchids' roots, nor the potting mix, to get enough air.

Hopefully some of this helped. In the end, growing orchids is a learning experience. I've been doing it for 15 years, and still find myself discovering new things.

-Tim

[WhiteRabbit]

Hmm ... seems odd you would get mold so quickly. CHC does retain moisture very well, but - shouldn't get mold in new media after only a few days. I use CHC a lot, and don't have issues with mold even in winter, so I don't know it that's the culprit.

I'd let it dry out, then soak the whole thing in the 3% H2O2.

[silken]

Hard to say from the pictures, but there seem to be coconut fibers showing thru the pot. Is it a bulky mix or rather fine? I like to use medium bark with a bit of moss but I don't pack it real tight and use clear pots with a good amount of air holes. That way there are air pockets in the pot and air can get into the pot from the holes. I would consider leaving it out of the ceramic pot for now as was mentioned, it would restrict air from getting in. I only use the decorative pots when one is in bloom to enjoy on display. Then it is just the plain plastic pot when it is finished blooming.

[supersheep]

Thanks for the help guys. I've taken one orchid out of the ceramic pot (it was on a bed of loose gravel - which was actually bone dry). The other orchid is a bit too top heavy to not stay in the pot though. It has stones at the base again though. It's still in flower and has had a few new buds open up this week.

I've poked my finger in the medium of both orchids and both feel bone dry! So I do think they've been drying out ok. But the mould seems to still be growing!

I've tried to take some better pictures through the pot. The roots look healthy and the black stuff at the moment is actually the medium, not the roots.

I don't really know how fine the medium is - it does have some coconut hairs in, and chips. I think there may be a bit of soil, because it feels powdery, but the bag did specify it had no peat.

Anyway, I'll try the H2O2, but how much do I need to worry about this mould? I do think, considering how dry the medium feels in both orchids, it should be time for another water...

[Tim C.]

Those are much better pics. It definitely looks like some small bits of mold growing in the mix. I'm stumped. I've seen similar mold growing in my mixes before, but it was always in moist mix.

Is the mold isolated to that one spot? Maybe it's just one bad piece of bark or CHC. I don't know what else it could be.

Let's hope someone has more ideas.

-Tim

[Stray59]

I think before I use the same potting mix I would sterilize it. I just wet mine then put a bowl of it in the microwave for about 4 minutes - stirring it about halfway through to get the mix thoroughly hot. Then I let it stand and cool on it's own. This usually takes care of such intruders as mold or mildew.
I think you just got an errant piece that had mold spore on it and the new environment has allowed it to bloom out. I wouldn't get too upset yet - watch to see if it infects the surrounding media and if so I would H2O2 it well. The roots look great!
Let us know!
Steve

[Rowangreen]

I've used the same medium and also found I get moldy bits. So far my plants don't seem to mind though, and I get good root growth. I think it is a bit more moisture retaining than I'd like for most phals, but it's so hard to get hold of good medium for orchids unless you send off for it or get to a show. I have been told that if it doesn't drain well it can soon rot to sludge as well, so watch out for that.

I'd cut some holes in the sides if you can to let in more air. I also think it helps if you can get some leca/clay pebbles and put a layer of those in the bottom of the pot.

[supersheep]

Sadly it's not isolated to just one piece of medium, it seems to be over quite a few now and I do think it's spreading.

It's in both orchids I repotted that day too...

It was the best medium I could find to order, and with it being a freshly opened bag, I never thought I'd need to microwave it. I will in future though.

I'm a bit worried about just leaving it though - as I do think it's spreading, and I think the orchids need some more water!!

I'll definitely watch out for any sludge though. I've learnt with my other orchids the perils of over-watering!

But yeah, so far, the roots on both orchids look uneffected!

[Stray59]

You know there are innocuous strains of fungus that cause no real harm to the plants - unfortunately, it speeds up the breakdown of the medium as the fungus is feeding on the deteriorating pieces. I have just read that some would recommend a cinnamon-wash; just boil a couple cups of water with a teaspoon of ground cinnamon added, let it cool and then water the plant with it. Cinnamon can halt the progression of many fungus and it may work - home remedy for those who do not have access to fungicides.
But, if it continues, or appears to be affecting the roots (roots turn black when it touches them or starts mold starts to grow on the roots themselves) then I would repot it in a sterile medium - after losing two batches of seedling that were just de-flasked to fungus, I started sterilizing all the medium I use - the medium came from a local grower who said it was sterile - it may have been at one time, but by the time I got it fungus spores had invaded it and I lost about 200 seedlings - Argh - but I learned my lesson.
Let us know what you do and how it turns out!
Steve