Q.damaged boxwoods
I applied some 10 10 10 fertilizer to my mature boxwoods (20+ years) in early April. A good portion (about 70%) of the boxwoods have since turned brown. Is this because I may have over-fertilized the boxwoods? Will they survive and return to their normal greenish color this summer? Should I apply a different type of fertilizer? Any suggestions or do nothing an hope it survives? Thanks,
Too much fertilizer is not good, as you know. Whether this was THE cause for browning leaves is not possible. When you fertilize, you must keep the plant watered. Fertilizers can build up in the soil to toxic levels. Not the nitrogen but the phosphorus and potassium. High levels of phos, inhibits the ability to absorb other nutrients, like calcium. 10-10-10 is fine for potted plants but too much for in-ground plants if used annually. Brown leaves are dead but the branches may still be alive. Before you fertilize again, get a soil test at your county extension service. But fertilizers are just the beginning. Boxwoods are prone to several diseases including "boxwood blight". Some others are reviewed here: https://www.gardeningknowhow.com/ornamental/shrubs/boxwood/yellow-or-brown-boxwoods.htm
