10-10-10 or 13-13-13 Downside

Q: I grow hydrangeas, azaleas, rhodendrons, camellias, and ferns plus my lawn. I notice that fertilizers offer different percentages of the three major nutrients and most plants have a “favorite” blend that is recommended. For example, grass likes high nitrogen, 24-0-11, while roses like a 23-11-8 blend. What is the down side of using 10-10-10 or 13-13-13 for most plants, except a lawn?

A: The downside of using any of the fertilizers you describe is that unless you’ve had your soil tested, you don’t really know what your plants want. Grass does indeed like high nitrogen products. Since most Georgia soils are adequate in phosphorus, the 24-0-11 would be fine (as would any other branded lawn fertilizer). There’s more downside to using 10-10-10 everywhere else. Again, most soils don’t need phosphorus and the shrubs and ferns you name really prefer slow-release organic fertilizers (Milorganite, HollyTone, E.B. Stone, etc). Soil testing is cheap, only $7 – $15. You might be wasting most of your fertilizer dollars if you don’t know what your plants desire. See www.georgiasoiltest.com.