As the growing season progresses, the gardener needs to monitor their plants’ growth. The goal is to provide the basic items that the plant needs to remain healthy. Last season, the focus was on best watering practices. This season, the focus is on fertilizing with an emphasis on nitrogen.
A soil test will identify what is in the soil for plants to use, but garden soils are not generally tested for nitrogen. The availability of nitrogen changes continually.
The addition of nitrogen to a plant in need is readily observed. Nitrogen promotes rapid vegetative growth particularly with grasses. It is a vital element in the formation and function of chlorophyll, which is a key ingredient imparting dark green color.
Adequate nitrogen for the plant has many important functions that aren’t visible. It synthesizes amino acids, which in turn form protein. Nitrogen will regulate the uptake of other nutrients.
With nitrogen, the goal is to have the right amount available at the right time for the plant to use. There may be enough naturally or some addition is needed. Each gardener will need to make that decision.
There are three nitrogen-only fertilizers likely available — urea, ammonium sulfate and blood meal. All are readily available to the plant by watering them into the root zone right after applying. They vary in concentration of nitrogen.
Urea is the most concentrated with slightly over two pounds equaling a pound of actual nitrogen. It would take slightly over eight pounds of blood meal to make an actual pound of nitrogen. A little less than five pounds of ammonium sulfate are needed.
Now is a good time to add nitrogen if needed for potatoes, peas and warm-season grasses. Other plants will need it during this growing season.