Geeze I meant railroad spikes. Duh! Haha!I use rusty nails or other rusty things in my herb gardens. Works wonders for them. Old rusty wheelbarrows are great for herbs It's the iron that comes from the rust that helps stuff grow. I don't know if it would work for the color change or not. Worth a try and better yet if you can find those old railroad ties to stick in the soil near the plants, but they are getting harder to find nowadays as the railroads don't use them anymore & people have scooped them up and selling for crazy prices in antique shops now.