In modern urban areas, soils tend to lack rich nutrients such as iron, phosphorus and magnesium. As a result, many gardeners are discovering a deficiency of these vital nutrients in their plants. When this occurs, supplementation of the soil through fertilization is necessary to correct the problem and ensure the plants have the nutrients they need for survival.
Test the soil with a soil test kit and verify the missing nutrients.
Determine the necessary fertilizer for a particular garden. If it's a regular garden, then lawn fertilizer provides an excellent source of iron. If it's an organic garden, then molasses can be used.
Dilute the fertilizer as specified on the directions. For chemical lawn fertilizers, follow the specific directions regarding dilution, and verify that the crystals are completely diluted in water before applying the liquid to the plants. For molasses, place 2 tbsp. of molasses into 3 cups of hot water and dissolve. That is enough organic iron supplement for four plants.
Thoroughly water in the fertilizer to optimize absorption and avoid root and plant burn.