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Basics of Garden Fertilization

bag of garden fertilizer

As the season continues and gardens grow, they undergo processes that use nutrients from the soil. Choosing the right type of fertilizer for your garden allows you to replenish lost nutrients and ensure optimum growth.

There are three macronutrients that plants require: nitrogen, phosphorus and potassium. Nitrogen helps produce new tissue, resulting in foliage production. However, too much nitrogen can cause the plant to grow abundant foliage and not produce flowers or fruit. Phosphorus enables the plant to set buds, provides vitality, increases seed size and stimulates root growth. The last macronutrient is potassium, which maintains the overall vigor of the plant. Potassium helps the plant fight off disease and regulate metabolic activities.

In addition to macronutrients, the plant also needs several micronutrients like boron, copper, iron, calcium, magnesium and sulfur. These can be obtained by using lime and adding organic matter to the soil. Soil tests are a great way to know what available nutrients your soil contains and what nutrients need to be added.

When choosing a fertilizer to provide nutrients to your plants, there will be three numbers on the label, such as 10-10-10. Those tell you what proportion of each macronutrient the fertilizer contains. The first number represents nitrogen (N), the second represents phosphorus (P) and the third, potassium (K).

The NPK ratio show the available nutrients by weight that specific fertilizer contains. For example, if a 50-pound bag of fertilizer has an NPK ratio of 10-10-10, it contains 5 pounds of nitrate, 5 pounds of phosphate, 5 pounds of potassium and 35 pounds of filler.

For organic fertilizers, the NPK ratio is lower than synthetic fertilizers because the ratio must show nutrients that are immediately available; however, most organic fertilizers are slow release, allowing the nutrients to become available over time. They also contain many trace elements that other fertilizers may not.

When you start to second guess using fertilizer, remember that those tasty cucumbers and beautiful tomatoes you grew last year took nutrients from the soil, and those nutrients must be replenished with fertilizer.

Brian Sparks, WVU Extension Agent – Nicholas County