Eggshells are the same as ground limestone, except in bigger peices that take longer to dissolve. Over the years eggshells would supply (only) calcium and raise the pH of the soil, which might be a good thing or a bad thing. Plants would still need a dozen or so other nutrients.

Egg shells are a soil amendment not a fertilizer.

There are lots of things mentioned on here that can be applied to the garden, including egg shells, and coffee grounds, and banana peels. These things are NOT fertilizers, because they do not deliver enough of what a rose needs in a monthly period to maintain good health and blooms. They are, as Karl says, soil amendments. By all means add them if you have them available, but don't expect them to take care of all your fertilizing needs. Roses are heavy feeders and need a lot of the right stuff to bloom and grow well.

Wow, three big rose guns on the same page. Michaelg, Karl Bapst, and Roseman, I would love to know what you three rose experts use for your fertilizing regimen. Thanks.

I like the idea of throwing something in the garden that would otherwise end up in the trash. But egg shells, banana peels and coffee grounds are not my only fertilizer

Although my disability keeps me from fertilizing as I once did, My best roses grew when I using my homemade organic mix. I then supplimented with fast acting 46-0-0 urea a couple of times during the summer and with soluble fertilizers through a fertilizer injector on my watering system.
I also used copious amounts of horse manure, usually applying it during the winter so the nutrients were available available when the roses woke up in the spring.
I worked my mix into the soil as I did my spring pruning. By the time it broke down the soil and weather had warmed and the roses were growing and were able to utilize it.
Organics are slow release and supply nutrients over a longer period at a slow steady rate.
Suppliments were applied in small increments, often.
A little fertilizer, applied often, provides steady growth and makes for healthier plants.

Here is a link that might be useful: My fertilizer mix

i would also add the warning that i fear composting egg shells would draw rodents?? i have heard of people putting the eggshells in water, then just watering with it, but personally, i hate mice and those sorts of things and wouldn't dare try the egg shells directly. anybody else have any experience with this???

Thanks so much for all the replies. I'm glad i learnt a few things. But the last post talks about rodents which ofcourse is scary. so maybe i'll stick with fertilizers. thanks.

All my garden scraps go into my veggie garden. I just dig a hole, drop them in and cover. I don't know about rodents- I have 10 cats... I would hate to throw any of that stuff into the trash to go to the landfill- what a waste. My soil needs all the organic matter it can get. Brandy