Answer: Here?s some basic info on fertilizer and nutrients that plants require. The 3 numbers on a fertilizer bag refer to the percentage of N (nitrogen), P (phosphorus), and K (potassium) in the bag. There are different formulations for different purposes. In general terms, nitrogen produces lush green growth, phosphorus helps strengthen stems and produce flowers, and potassium keeps the root system healthy. If you're applying fertilizer to fruiting (e.g., tomatoes) or flowering plants, you're not as interested in the plant developing leaves as you are in it flowers and fruit, so you'd use a formulation lower in nitrogen and higher in phosphorus, such as 15-30-15. If you are only interested in foliage growth, the nitrogen would be higher, such as 21-0-0. Some bulb gardeners like to use 0-45-0 mixed into the bottom of the planting hole to enhance bloom. There are many formulations for all types of plants with variations in these ratios. Watch out for very high numbers (such as the 21-0-0) as they are concentrated and can more easily burn plant roots. Hope this info helps!
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