[Aston]

Hello Everyone!
I have planted a number of (soft bag type) patio planters this year - with potatoes, strawberries and other veg. When I moved the planters today I noticed that they had left rings on concrete patio slabs. It is as if the colour in the concrete slabs has been etched by acid (or something) around the outside of where the bags were sitting.
Any ideas?
Thanks, Aston

[Elcie]

Not sure to be honest Anton.  Have you tried scrubbing the mark away?  Would have thought this would work.  Unless the bags themselves have left some kind of residue.

[GrannieAnnie]

Do you use tap water to water them?  Could it be you have hard water and that is the limescale??

You can get stuff to clean slabs and brick off at DIY places.

[Loubs]

I've got a container garden, so occasionally move pots about, especially at times when I'm about to go on holiday (tend to move things over to the shady side - and then back again to the sunny side when I return). All my pots leave a mark, which generally fades over a few weeks.

[Aston]

Thank you, all, for your thoughts.

I guess (whatever the cause) the answer is probably to move the containers around reasonably frequently, so they don't sit in the same place for too long.

Very helpful forum - thanks again.
Aston
 

[BenefitofHindsight]

Aston,
You may want to check this out:

http://www.ehow.com/how_4996050_remove-water-stains-concrete.html

BoH