How to Compare Granular Fertilizers for Blooming Plants
- 1). Have your soil tested to find out what macronutrients are there and in what quantities. Nitrogen, phosphate and potassium are the macronutrients that contribute most to plant growth. Each plant needs a specific combination of these to thrive, and its growth will be limited in proportion to a deficiency in the scarcest of the three nutrients. So the fertilizer that will keep your plants the healthiest is the one that provides what's missing in your soil, and provides it in the ideal proportions. Fertilizer should supplement the nutrients present naturally. Bear that in mind when you select granulated fertilizers for your flower beds.
- 2). Look at the N-P-K numbers listed on the granulated fertilizer packaging. Those numbers tell you the percentages of nitrogen, phosphate and potassium in that fertilizer, and they always appear in that order. Generally, to grow the healthiest blooms in the greatest number, you want a 1:2 ratio of nitrogen to phosphate. Nitrogen tends to encourage leafy growth, while phosphate encourages flowering and fruiting. You also want to make sure there is at least some potassium in the fertilizer to encourage a strong stem and roots.
- 3). Examine the differences in concentrations between different fertilizers. A fertilizer with a 5-10-5 for N-P-K numbers is half as concentrated and needs to be applied twice as often as one with 10-20-10. If you live in a dry climate, your plants may do better with the less concentrated and more frequently applied grade, because then the fertilizer is less likely to burn them. In any case, you should never apply fertilizer to dry soil.
- 4). Cater to specific needs for specific blooms. African violets, for example, like a higher concentration of nitrogen than many other flowering plants do. Azaleas like acidic soil, but should only be fertilized to achieve that acidity when they are out of bloom. Research the needs of each of your species of plant to be sure of their ideal growing environment, and choose your fertilizers accordingly. The 1:2 nitrogen to phosphate ratio works well for most.
