Yesterday I well fed my cannabis sativa (Wikipedia) plants with fresh shredded extra roasted Starbucks coffee under the assumption they will grow better, but instead of that this morning I saw the left half of my plant was abused and deeply shrunken. Is this because of the nitrogen in the coffee?
It appears you watered your plant/s with an actual cup of coffee, and that you did not dilute it beforehand, though hopefully, the coffee did not contain milk or artificial creamers, nor sweetener/sugar, was not still hot and you did not put the grounds on the soil too.
If you must use coffee, it needs to be cooled and diluted with as much water again, should only be applied occasionally, and then only on acid loving plants. Your cannabis plants like a soil ph of between 6-7; coffee is acidifying and has a ph of 5.2-6.9, depending on the beans and preparation, but cannabis prefers more alkaline conditions, so frequent use of coffee will mean a rise in acidity in the soil conditions in pots. Probably best to avoid using at all for your plants https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/diluted-coffee-for-plants.htm
Coffee grounds have been found to NOT be any kind of a substitute for fertilizer or for feeding the micro and macro organisms of the soil. Very acidic as well. I would never use coffee grounds in my soil. Not worth it.
Cannabis plants like a more neutral to ALKALINE soil, NOT at all a neutral to ACID soil.
Best advice I could give you is to buy! Jorge Cervantes "The Cannabis Encyclopedia". Incredible detail and this book may be all about ONE plant but this book is so educational about all plants. Cannabis is the best thing to happen because it is making great gardeners! No Cannabis grower will be using these lame fads of No Till, No Fertilizer, Back to Eden, Hugelkultur...grins!!