This is a good question. I use a generic 10-10-10 fertilizer around the plants in early spring. Probably the wrong thing to do and totally useless, but it make people feel good. I know a soil test would be the first thing to do, but so much time just for a bed of 3 shrubs.
Always hated fertilizing existing shrubs. At least if I planted them, I know they have good soil and nutrients then. I really believe in staying away from ferts if possible and letting plants grow as they would. As long as the right plant is picked and you examined the soil before hand, I think they should do fine without any fert. Then again, I've seen Bartlett spray, and there stuff looks NICE.
How do you use the 14-14-14. Do you just spread it around the beds, then till it in. Or do you just spread it and let work its way into the soil. Also, what do you do for new planting. I someimes mix it in with the soil and throw some in the holes before planting, but always get nervous about root burn and any other problems.
Also, what kind of rates. When you read the bag, they say something along the lines of 3-4 lbs for 1000sq ft, and then 1 lb for inch of caliber, at least on that 14-14-14.
I just wonder if the fertilizer really gets to the roots or not, especially when just broadcasting it, and even when working it into the soil. The ground injectors, and foliar spray ferts seem like they are much more effective.
Generalization: fertilize shrubs = better growth = more work to keep in bounds. Most landscapes are too tightly planted, even if they're not, why rush the growth process. Fertilize with appropriate count of Wood Ace bricks when planting, and fertilize established plants when in stress. In our area, this means you are almost guaranteed to be fertilizing azelias and rhodedendrons, mainly to maintain the necessary acidic environment.
Say, what do you use for azaleas/rhodis and other acidic loving evergreens. Is Hollytone a good way to go, or is there others. Sometimes I think that old fashion miracle grow is the way the go.
As I remeber, I've also used garden rich (5-10-5) for a lot of planting, such as perennials and shrubs. The 10-10-10 is product called shrub rich, and it also has some iron in it. Only use that on woody shrubs though, at least that is what they suggest.
I agree with the shrubs being planted to close. A extremely commom problem, and really a shame to see. Inproper design can account for a large percent of plant health problems. No one seems to understand that when you plant a acorn, it turns into a oak. Thats the saying I like to use at least. They just see the plants as they are, not in the future.
Steve, have used ferti-lome Azelea Evergreen Food with insect control, since seeing az/rh in a local nursery. He had used this for many years, and his plants were fabulous. Since we're in same soils, works good for me, too. It is a 9-15-13, plus systemic insect, plus micros.
Have always removed mulch, fertilized, raked in (but don't damage roots), and replaced mulch. Label advises this. Also knowledge of high cec of mulch, and fact that decaying mulch binds up nutrients, to spread fertilizer on top of mulch is useless. You can charge for fertilizing, because you put it on, but the plant receives little or no benefit. But have to use judgement on amt of mulch removed in a long established bed with shallow rooted varieties. Hope someday someone makes a good granular injector; would save a lot of time, but would it do as good a job?