Dear Katia,

fertilizers are important for all plants, especially if they are potted plants, and especially if they are bonsai, which have a tiny pot; in nature the plants of the forest do not receive fertilizers from man, and therefore they obtain the mineral salts they need from the soil; but on the one hand, the root system of a tree in the wood has the possibility of spreading “as desired”, in search of the salts it needs; on the other hand, around the trunk of a tree leaves, seeds, fruits, small dead animals and the manure of forest animals fall continuously: in this way the forest soil recovers a lot of material from the environment, which decomposes , releasing many substances into the soil that the trees need, in a slow continuous process. The conditions of the soil of the pot of a bonsai are very different from the natural ones: the roots of the bonsai absorb mineral salts essential for the development of the plant, until they are no longer found in the soil. And at this point we either change all the soil, or we add fertilizer. When choosing a fertilizer it is always good to choose the specific one for the plants we are growing, because each plant has different needs; if possible we choose the best on the market, which contains nitrogen, phosphorus and potassium, but also microelements such as boron, zinc or manganese, just like your fertilizer. In particular, the fertilizer you purchased is rich in phosphorus and potassium, a little less than nitrogen; it is therefore more suitable for summer and autumn fertilizations, less for those at the end of winter, in which a slightly richer nitrogen fertilizer should be used. Since you are a beginner, I think it is early to buy many different fertilizers, one for each season; rather, learn to use what you already have, and learn a little about how the fertilizers are composed, so that in the future you can choose the fertilizer that you think is more correct. As a general rule, when we do not know a fertilizer well, it is good to supply it in small doses: in this way we will guarantee a certain dose of mineral salts to the soil of our bonsai, but without risking excesses, which can burn the roots. The explanations on the bottle of your fertilizer are quite confusing, first they give you the dose in ml, then they tell you how many grams the measuring cup contains; however, consider that, if it were water, one gram and one milliliter occupy the same volume; therefore more or less 10 ml of fertilizer fill half a 20 g measuring cup. I advise you to provide small doses to begin with, so half a scoop every two liters of water (in this way you stick to the wording on the bottle, which says 5-10 ml per liter of water, but staying on the lowest dose); every 15 days more or less is fine.