I used Fertilome LCFe many years ago on some of my roses when I lived in an area with a lot of limestone rock formations. I would suggest you use the lowest dose recommended on the bottle to start with. I just looked at a Fertilome LCFe label on line & the lowest dosage was 2 TBSP per 1 gal of water, apply 1 gal of this solution to a 2ft high plant (if you are using another brand of LCFe, follow their mixing instructions). Apply as a soil drench to a couple of test plants, wait 3-4 weeks & see if it resolves the problem you are trying to address. If it causes some other problem, don't apply to your other roses; if it solves your problem, then apply to your other roses; & if it partially resolves your problem, then you may want to up your dosage per plant. Also remember LCFe stains everything....clothes, skin, plastic buckets, concrete, etc. so handle accordingly.

This post was edited by wirosarian on Tue, Apr 22, 14 at 11:51

Just a heads up! I used it on my Rhododendrons....It made the most beautiful forest green foliage. (Sprayed). So I did it again. The rhodies were in bloom! About two hours later, I looked out and the blooms were healthy, but had taken up the iron and were all black edged. I don't think I would do the roses if they are in bloom, and you plan on spraying. The foliage was gorgeous.
Good luck!

Thank you for the responses and for that warning! I plan on using it as a liquid drench. Our local society's rose show is the first Saturday of May, and I just want to green up the foliage on a few bushes, including a Reine des Violettes growing in a large container. Will go the low dose route that you recommended, wirosarian. Thanks again!