Container mold -- again!

sugi_c(9a)June 27, 2013

This is the second time this is happening this season. Originally I had a blue clay pot that did a white fuzzy mold thing to no end (inside my home), so it got tossed.

Since January, I've had this half barrel type planter out on the balcony. In the last week, this ridiculousness has started.

Does anyone know why this would happen? I bought this one at Lowes, I believe. I guess first, is it true mold and second -- what now? Instinctively, I want to pull out everything and toss the planter itself. But I am loathe to pull out the blueberry it houses right now which has fruit ripening right now.

The soil is a special blueberry acidic soil my nursery makes with sulfur, etc added. For the blueberry, I keep the soil relatively moist (watering 1-2x a week) but not soaking wet. All of the mold is on the top 1/4 of the pot, most on the top rim and some of these lead down to (or come up from) the soil whereas some splotches are just on the top.

I'm having a bizarre gardening year!

Thanks for any guidance you can offer on this. I guess I will bleach the crap out of it tomorrow and see if it kills the plants or not? I'm at a total loss.


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Some more images...

    Bookmark   June 27, 2013 at 10:54PM
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And another spot -- last photo.

    Bookmark   June 27, 2013 at 10:56PM
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edweather(Zone 5a/b Central NY)

Well it seems that because it's wood and is constantly wet that mold is forming. I can't really explain it, but it seems that if the container were plastic you might not have the problem. Yeah, I'd probably just wipe it off every now and then.

    Bookmark   June 27, 2013 at 11:46PM
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chilliwin(EU DK 7)

A possible disadvantage of wooden containers. I have no idea how to deal it.

Good luck to find a solution.

    Bookmark   June 30, 2013 at 9:13AM
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calistoga_al ca 15 usda 9

I am guessing you are keeping it too wet. Water half as often with trice as much water. Mold requires moisture to grow. Al

    Bookmark   June 30, 2013 at 10:05AM
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I would not get any bleach or agent in my soil. Let it dry out a is not a deal breaker. Have you had damp weather? Could this be mineral deposits from very hard water?

    Bookmark   June 30, 2013 at 11:10AM
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Ohiofem(6a Ohio)

Grace: I am in the humid Ohio River valley where we've had about 2 inches of rain a week since the beginning of May. I grow an elephant ear and a hydrangea in similar wooden tubs. I just looked and found a very similar mold on the side of the one with hydrangeas in it. The soil is 5-1-1 with extra compost added to make it hold more water. It has no lime in it.

I wouldn't worry about it. Try cutting back your watering some. Instead of bleach you might try wiping it off with white vinegar. Vinegar is an herbicide at full strength, so keep it away from your soil and plant. But it's safer than bleach.

    Bookmark   June 30, 2013 at 2:31PM
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I agree vinegar would be a safer choice, but a mild bleach solution applied only to the wood shouldn't be harmful. You would have to be careful to avoid the plants, but there are gardener s who use a bleach solution on their plants to prevent fungus, so who knows? I would switch to plastic or the grow bags next time around.

    Bookmark   July 4, 2013 at 2:25PM
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Hydrogen peroxide might work as well. It's not as harsh as bleach, but I would avoid getting any on the plants, though.

    Bookmark   July 4, 2013 at 3:29PM
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Hi Grace!
Yes, it's a fungus, but I don't think it's one, that will do harm to your plants.
I agree with Fireduck, and would avoid using bleach. Especially if you want to eat those blueberries later on (I have no idea if bleach can get absorbed from the roots, but I would not risk it). I would rather just try the vinegar, or simply let it be. Not all fungi are plant killers, and chances are, that it's just something that prefers living in decaying wood.
It's a shame though, I remember seeing a picture of that planter, and thinking it was so pretty! It was probably not the right kind of wood for job though.

Good luck with it,

P.S. I actually think that fungus looks rather funky. Might look great, together with the blueberries, once they ripen. ;-)

    Bookmark   July 8, 2013 at 4:10PM
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Time for a science experiment!

The vinegar is your best bet, plus any leaching into the soil will likely only help the blueberry.

Another thing that you may like to try is cinnamon. Either make a paste with the vinegar and apply to the exterior of the pot or just sprinkle some on and see what happens.

Other oil-based natural treatments may work. Hot pepper oil, rosemary, etc.

For fun's sake, why not try a little fire? Traditionally fields are cleared and blueberries bushes are "pruned" by controlled burns. Why not try a quick torching of the pot to see if that helps?


    Bookmark   July 8, 2013 at 8:59PM
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Thanks for the responses.
I had a project pop up and then neglected to take on the mold, not to mention watering everything religiously (except the tomatoes)-- which, of course, alleviated the mold issue while the blueberry in this pot suffered.

It's still there but infinitely less, as I now take care to water just the soil without hosing the whole pot freely, but it does seem ridiculous to me that an outdoor planter can't take a slightly wet pot! I'd demand a refund if I could even move this thing, haha. The slightly warmer weather is probably drying out the pot quicker, too.

Ryan, I did take a BBQ lighter to it before I ever posted this thread, haha. I was just sitting there looking at it, and .... well, it's kinda pyro of me, but I tried it. Knowing me, though, if I tried to do a controlled burn on this, I'mma set the whole building on fire.
I'll try that vinegar + cinnamon idea.

Ohio, are you treating it or leaving it alone?


    Bookmark   July 9, 2013 at 9:23PM
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Ohiofem(6a Ohio)

Grace: Back away from that flame thrower!

I haven't tried to stop the mold. And we are having so much rain -- including 3.5 inches in an hour on Saturday -- that i have been thinking i may need to use that tub as an ark!

My attitude is that I don't want to hurt living creatures that aren't hurting me. The ecosystem is a complex and beautiful web. We don't appreciate how it all works together, so we should show respect. I love wood containers, but I have noticed that they deteriorate pretty rapidly. That's the purpose of dead wood in the ecosystem. The fungus loves it.

    Bookmark   July 9, 2013 at 10:45PM
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