I have a very small number of rocks (lime rocks?)--the pretty kind with the holes in them--that we brought from the river years ago. We also transplanated some woods fern that comes back each year and gets 3-4 ft. tall. I decided today to put some of my potting soil in the holes and put some color with the fern. I'll probably plant some of the Proven Winners superbena that trails. I probably should have tried to clean the rocks BEFORE I put the soil, but I wasn't thinking. Is there anything I could use to clean the rocks with before I put the plants in there? Obviously, I want something that won't kill the fern or plants.
This is my first time visiting this forum, so if you have any other suggestions, they would be appreciated.
How do I clean the river rocks?
It's hard to answer without knowing what it is on the rocks that you're trying to clean off.
It looks like some type of small growth, probably moss, and just dirt that has accumulated over a period of time.
Hmm, many people go through some effort to try to get moss to grow on garden objects (troughs, pots, rocks) - it makes the object look a little more natural, and established. However, if that holds no appeal, why not just use a wire brush to remove the moss and dirt?
I probably answered your question too quickly, as I was exhausted from working in the yard. It may not be moss, as we have hanging from our old oak trees here, but some other type of growth. I will take your suggestion and use a wire brush, but I was wondering what type of cleanser, if any, I could use to make it look whiter without harming the fern. Thank you very much for your response.
Well, any acid (e.g. 10% hydrochloric acid (HCl); or "muriatic acid" which is also HCl) that's strong enough to dissolve the surface layer of the limestone and thus dislodge dirt and moss would certainly do other plant life absolutely no good. Mechanical action is almost always the simplest and most effective, despite the little bit of physical effort it would take.
I would suggest being very careful about cleaning with acid, as traces could hurt your plants if not neutralized by the rock, itself. I suspect it would be, but I, personally, would rub thoroughly with a baking soda paste (neutral pH) and rinse like crazy if I used any acid. Vinegar is also a milder acid that could be used.
HCl would only be "neutralized by the rock itself" after the reaction of the acid with the limestone (CaCO3) was spent... in other words, after all the fizzing and bubbling and popping died down. The fizzing, etc. is the reaction that would remove the outer layer of limestone, if enough acid was applied. At the point that the reaction stopped (i.e. the fizzing stopped), there would be little point in applying baking soda.
After first burning the plants with an acid, following up by burning them with a basic solution (baking soda and the water generated by the previous reaction) would not be helpful. (Baking soda does not have neutral pH - it is a base, the opposite of an acid). Strong basic substances also burn plants and flesh. Sorry, but it's the simplest chemistry... and that's why I suggested using a wire brush, LOL!
This reminds me of why I didn't take chemistry in high school decades ago. I really do appreciate all of the advice, but I think I'll just stay with your idea of using a wire brush and keep things safe and simple.