Have you tried eggshells as fertilizer for your orchids? it is common knowledge that eggshells, when crushed and added to rose plants, can induce bigger flowers. However, recently I found out that if the whole egg is beaten along with its shell the not only the size of the flower increases but it also enhances the production of scent.

How to fertilize with eggshell
Orchids can also benefit from powdered eggshells fertilizer. Here shells can be saved and crushed, powdered eggshells can be added to orchid growth medium. Another way to fertilize with eggshell is to boil about 5 to 8 shells in 2 to 3 liters of water. Use this water after it cools down when watering your orchids.

I have used rotten/bad eggs also to fertilize my plants. The eggs need to be beaten thoroughly and add only half a spoonful. It works best for ground orchids where the orchids are growing in soil. In case of porous growth medium dilution with water is highly recommended and even after a dilution use only a very small amount. This is so because when fertilizing with eggs or with eggshells we need to take some precautions.

Eggs have strong smells, especially if they are rotten or have turned bad. I found out the hard way that adding eggshell that is not crushed properly can invite birds, like crows to plunder the growth medium. Pets can also dig up to extract the shells. So crushing these into a fine powder is a good idea.
Further, it is better to dig a small trench in the soil around the orchid (terrestrial ones) and after adding the egg or eggshell cover it with the soil that was removed. This will hide the smell of the egg. Hopefully, if done properly this will work though for some of our ground orchids and other plants it did not work as our pet dog dug out some of the eggs even after this!
If eggs/shells are added to a porous growth medium then the smell is more likely to attract ravagers like birds and pets. So adding in small quantities will help.

Did this help? Let me know your thoughts and give your comments on our Orchid forum.