Sounds like you have what they call shotgun mold shotgun fungus or artillery m.
Mulch mold on vinyl siding.
Pressure wash the siding on your house.
Add a fresh layer of mulch.
Plant a low maintenance groundcover in the area instead of using mulch.
There is research to suggest that blending mushroom compost at a rate of 40 with landscape mulch can suppress the spores.
Use big pieces of pine bark or other bark mulch which are a less hospitable place for the fungus.
You can power wash them off of vinyl siding but such methods can be damaging to cars and wood siding.
The artillery fungus or shotgun fungus is a wood decay fungus that likes to live on moist landscape mulch.
In extreme cases removing the mulch from your property completely and using an alternative stone or non wood mulch may be the only permanent solution.
Over time and through repeated changes in weather vinyl siding will attract and develop mold or mildew spots especially in north facing and other shaded areas.
In effect it looks like someone shot your house with little tiny bullets.
I also tried krud kutter and a scotch brite sponge which works but it would take five years to clean the siding that way.
I have heard that the mulch can spit its coloring out and also that it could be mold from the mulch.
This mold found on house siding looks like small black dots.
Mold removal usually requires some scrubbing and the best tool to use is a stiff bristle natural fiber scrub brush avoid metal fiber brushes they can damage the siding.
There is no fungicide registered as an artillery fungus treatment.
Also the use of gravel or plastic mulch will not.
Replace wood mulch with landscape fabric and small stones.
Here is a photo of what the actual fungus that produces the black spores.
How to prevent mold on vinyl siding.
In order to kill artillery mold you must remove the spores from your siding and from the contaminated mulch that brought the spores to your home.
Do you have little black spots all over your car or siding.
Vinyl siding is undeniably growing in popularity and with good reason too.
Here is what the spores look like on the vinyl siding.
Vinyl siding is made to withstand cracks chips and fading.
The worst thing about this fungus is that it shoots spores up to 20 feet which often land on siding cars.
The vinyl siding institute yes there really is such an organization offers some helpful and specific tips for dealing with stubborn moldy spots on your siding.
Making a habit of cleaning your home s siding flower pots and outdoor furniture with a biodegradable cleaner will prevent the spores from staining the surfaces.
It s attractive and durable plus it holds up better than wood siding.