Follow the directions on amounts to be used on the fertilizer label for roses/flowers.
Roses will not mind slow - release fertilizer.
I have no comment on the formula published in your local paper years ago. Maybe someone else can answer that one.

Using 1C will not harm your roses, so I would do that.

In order to compare, we really need to know active ingredients. But since you are going to the slow release, you can at least double it.

Yes, you will need to double the amount of the organic 5-5-5 to get the same amounts of NPK in the chemical 10-10-10. This is one of the reasons why organic fertilizers are expensive to use, you need to use larger amounts because their NPK % are usually in the single digits. A well known commercial organic rose fertilizer, Mills Magic Mix (6-5-1)tells people to use 2 cups per bush 2-3 times per year (miniatures 1 cup) with a monthly application of Mills Easy Feed so 1 cup of your 5-5-5 should be OK.

Regarding the recipe, 1/2 cup of 12-12-12 is too much unless spread evenly over an area of, say, 4 x 4'.. For an average plant I apply a handful, less than 3 oz. Chemical fertilizer needs to be applied more than once a year because the nitrogen only lasts 6 weeks, regardless of quantity applied. The bone meal is redundant since the 12-12-12 has way more phosphate than the rose can use in a year. The chicken manure poses a risk of burning if applied along with a lot of chemical fertilizer-- both contain fast nitrogen.

Mixed organic fertilizers are usually applied at 1-2 cups per square yard and maybe 5 cups per year for your very long growing season.

The main differences (beyond the lower analysis) are that mixed organic fertilizers:
1. contain trace and minor elements
2. contain slow nitrogen that is released over approximately the whole season
3. contain less fast nitrogen, so that greater amounts can be applied at once without burning.

Follow the recomendations on the label. If you were baking and wanted a sweeter product, would you double the sugar in a spcific recipe? I think not. So 10-10-10 is not the same as 5-5-5 doubled.

Thanks guys! As with most of life, not one answer. I do appreciate your suggestions and will do something. My roses have looked fine so far, I just have this thing about trying to do the "right" thing!! I need to remember there are many "right things." :)
Ginny

And what is "right" for someone else might be "wrong" for you... ;-))

There is a huge variation of "right" in Connecticut, since we have both soils of mostly clay and mostly sand. Those with sand need much more fertilizer than those with clay.

@roseman(Z 8A GA) ...You are so very wrong! 10 10 10 is the same as 5 5 5 double and that is a fact. You need to do your research, before making comments like you did. I cannot stand people who gives B*llSh*t info. The (NPK) numbers are represented in concentrated strength. My info is backed-up and sited here: Fertilizer

@Roses ...Yes ...and 20 20 20 is the same as 5 5 5 quadrupled. For more info, see: Fertilizer