How do I remove plant stains from concrete?

[tordell]

Hi,

I was doing a driveway job the other day. The concrete came out looking very nice except the portion where a planter had been. The planter had been flooded over who knows how many times and had left a ring, and streaks, i'm supposing from some sort of minerals in the potting soil, or fertilizer. Does anyone know what i'd use to take these types of stains out?

Here is a picture you can easily see what I'm talking about.

Thanks,

Dave
Murphree's Pressure Washing

 

[Mark]

Probably going to need to use acid.

I would start with a weak solution
then go stronger as needed.

 

[MR ALAN]

I concur with Mark on the acid, and when he says weak, it means have patience. Go to strong and damage the surface and their is no turning back.

 

[john orr]

I see these from time-to-time and I first apply strong chlorine, allow to dwell for 10 - 15 min then rinse thoroughly. If any stain is left (and there likely will be) oxalic acid is my choice (Rust Aid from HD in a pinch) but be aware that the oxalic will brighten all concrete you apply it to.