
Hello and thank you for your questions sent to us here at Gardening Know How. I will provide you with some links to articles on these subjects. Eggshells need to be smashed up into fine powder to provide benefits quicker as large pieces take a long long time to get broken down. Vegetable peels and cow dung should be composted together for a while so they get broken down and thus of more use to the roses without burning the roots or causing root mold or rot problems. Ash is not something I recommend as it can be extremely harmful depending upon what the ash is from and its acidic content. I personally like an organic based rose food that is reasonably priced by Richlawn Company called Gro Rich Rose and Perennial Food. I am not sure what might be available in your area, ask at your local garden centers to find out what is available. Here are links to some articles for you:
https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-fertilizer.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/best-rose-fertilizer.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-soil-preparation.htm