Blue Hostas staining concrete wall

[bscuzz]

Cheers Everyone and Chris! My venture to Hallson Gardens is in search of Hosta information. After having beautiful Blue Hostas alongside my house for 7 years, I find this year that when I checked out this area I have black stains on the cement basement wall at each location where a hosta resides. My question is has anyone had similar problems? I assume these black splotches resulted from whatever remained after the hostas bloomed - since they are high enough not to have been from the leaves themselves. Cleaning the splotches on the concrete walls is turning into a pretty labor intensive project. My thoughts are that maybe I need to cut back the bloom stems as soon as they finish blooming to avoid this problem. Since I won't know if this will work till next year, I was hoping someone may have the answer. Any help will be appreciated. "bscuzz"

[Chris_W]

Hello,

Sorry we haven't been a wealth of information on this, but I think, like others, I don't have any good answer for you. I've never heard of hostas staining the side of a house or fence or anything else Do you think that spot might have just been extra shady and extra damp, so there is some mildew buildup there?

Hopefully some strong bleach will help to wash it away. The only thing might be to thin or move the plants further away to provide more air circulation.

Sorry I couldn't be more help.

Chris

[Pieter]

I'm with Chris on this one, sounds like mildew to me, most likely because of an issue with the water proofing of the wall in question. You may not like the sound of this, but I recommend digging a trench right along the wall and have a look at what the water proofing looks like. If indeed there is an issue with it, the whole perimeter of the house will have to be dug-up and the exterior wall will have to re-sealed. Outside of the health hazard that mildew can cause, dampness in a wall going through repeated freeze/thaw cycles lessens the strength of the concrete and may lead to crumbling. You could very well be looking at a fairly pricey remedy, but the alternative could be a collapsing house....

[largosmom]

Try spraying some bleach water on the wall to see if the color goes away. Bleach will kill mildew and fade it.

Laura