When you are feeding your garden or farm, chances are you are going to purchase some fertilizer from the agricultural store. These bags of fertilizer have three numbers that gardeners must know and understand how they affect the growth of their plants.
These three numbers on fertilizer bags are: nitrogen (N), phosphorous (P), and potassium (K) (sometimes referred to as potash) levels. The numbers represent percentages based on weight. For instance in the bag is 5-5-5 this means that 5 % of the bag is nitrogen, 5% phosphorous and 5% potassium.
So what does nitrogen, phosphorous and potassium do for our plants?
- Nitrogen (N): nitrogen is very important in developing leaves on your plant. It helps the plant develop dark green foliage (builds chlorophyll) to collect sunlight. Be careful when adding fertilizer that is high in nitrogen. Too high of a content may actually burn the plant stems. Any fertilizer that is over 10% nitrogen, I till into the soil before I plant my garden. Chicken manure is typically very high in nitrogen.
- Phosphorous (P): Phosphorous is important in developing roots and aids in blooming. Phosphorus is generally derived from rotting organic matter such as bone meal. Native Americans used to bury parts of dead fish that they did not eat in their garden to boost the Phosphorous levels. Phosphorous deficiency can be recognized by dull green leaves (sometimes yellowing) and purplish stems.
- Potassium (K): Potassium (potash) is important for the general health of the plants. Potash helps to build chlorophyll and other plant compounds. Potash is also known to help build disease resistance in the plant. Potash is also important in cold tolerance of the plant. Potash can be increased by adding ashes from your chimney to your garden.
Don't let these numbers intimidate. I follow these basic rules:
- When initially tilling in the spring, I add high Nitrogen and Potash
- Mid season I add a high Phosphorous to increase blooms and fruit
Hope this helps. Remember to always compost and add this to your garden. Your compost is generally low in N-P-K. But it is a good source of free fertilizer that will slowly boost your soils richness and your plants will thank you.
