I've always thought it would be an interesting grade school science fair experiment to see what would happen if you used ordinary sugar as a fertilizer for plants. I had thought sugar contained nitrogen, a crucial element for plants, but it turns out not to be so. Sucrose, the most common table sugar, is C12H22O11. No nitrogen there.
In fact, sugar would remove nitrogen from the soil.
There are many microorganisms that can consume nitrogen as part of their natural life cycle. Researchers at Charles Sturt University say that feeding and encouraging these organisms to grow is one of the most effective ways to reduce nitrogen in the soil.So there you have it. Don't feed your plants sugar.
(It would probably give them cavities anyway and who wants to be taking their begonias to the dentist for a filling?)