Bleach works, but if the house is in a generally damp area, and the siding is facing north, the mold (fungus) will just come back. You basically have to stay on top of it, remove any tree branches that are up against it, make sure your waterspouts or gutters aren't keeping it wet a lot, and ask at the hardware if there is anything you can apply to slow down growth.

This is probably ,artillery fungus ,unfortunately there is little you can do to remove it.

Here is a link that might be useful: fungus

Mold grows on siding when it doesn't get sun on it for most of the day. I have areas of mold on my steel siding. It has little to do with the area being damp. You'll even see it where a window shades the siding and it can't get direct sun on it. I mix up some bleach water and use a scrub brush.

Thanks. It's not a damp area and the house does get sun at times throughout the day. Started on the more shady areas but now it's on all sides. Will try a bleach solution. Do you mix it 50-50?

50-50 in a garden type sprayer wearing long sleeved rubber gloves, eye protection.

Thanks. It's not a damp area and the house does get sun at times throughout the day. Started on the more shady areas but now it's on all sides. Will try a bleach solution. Do you mix it 50-50?

Did you read the link?

I don't pay much attention to the ratio. More bleach will mean that you have to use less scrubbing to get rid of it. Just be careful around your plants. I wouldn't use a sprayer--the breeze can make it land on your plants. You can control it better with a rag and scrub brush.

If you have little black dots, then 'christophern' was
correct. Artillery Fungus, and it doesn't come off!!
I had it, and it was growing in my mulch. Google
it and you will be able to read all about it.

It is little black dots BUT it does come off. I can wet a finger,rub the spots and it comes right off but other chemicals so far hasn't really touched it. My neighbor has tried a product we are waiting tosee with... I read the link, didn't mean to offend you by not mentioning it prior to re-posting...
Thanks again for the help everyone.

Do you have trees in the area? In some areas, different species of trees drop liquids in spot form this time of year. Might not be mold/fungus.

Sierra the only trees that are close are very mature Ponderosa Pines and they put out pitch and pollen but nothing else that I've ever seen... Do you think they might have some influence? The siding has been on the houses for 12 years and now everyone is talking about the black spots so it's really a town issue, LOL, but one we need to figure out. Thankfully I only have one area that has plants next to it so the bleach solution wouldn't hurt them but not sure about my deck stains... Oh well, home ownership I guess. Thanks everyone.

We found a solution that works!!. It's mouthwash and toothpaste. Though we replaced the toothpaste with the Mr. Clean Magic Eraser. You can find the details at http://www.personal.psu.edu/users/d/d/ddd2/. It's an article published by Penn State University. Go to the bottom of the article under "Reader's Suggestions For Removal From Houses" #18.

After reading all over the internet about how the experts say you can't do anything about it, a 10th grader from Battlefield High School in Gainesville, Virginia came up with the answer.

There are hundreds of articles on-line saying you canÂt get the spots off. But, The kids method works! We did refine it a little by replacing the toothpaste with the Mr. Clean Magic eraser.
ItÂs a breeze we wet a paper towel with mouthwash, wiped down the spots until they softened and wiped off (6-7 swipes did it) and went over the stain with the Magic eraser. The spots were completely gone.

Help my entire back of my house is bad.... are you all really saying that scribing is the only answer? I can use a power washer but I'm to ill to do the scrubbing. Any advice? I've tried bleach, products and it get better but this is after 4 power washing and multiple products?

How long ago was the last power washing? And did washing get it clean and it grew back in that amount of time, or is this what it looked like after power washing?