As plants use the nutrients in soil, they must be replenished or the nutrient content will eventually be diminished. Organic fertilizers are generally accepted to be better for your plants, for you and for the planet. When added to the soil, fertilizers provide the nutrients that plants need, but plants can also absorb nutrients directly through their leaves in the form of foliar sprays.
When added directly to the soil in the fall, plant matter (or humus), will decompose naturally, adding the three main plant nutrients (nitrogen, phosphorous and potassium) as well as significant sulfur content to the soil.
Turn compost, one of the most nutrient-rich fertilizers available, directly onto the soil in the spring, at least two weeks prior to planting, to start with a garden bed that is rich in nutrients.
Add top dressings of compost or other fertilizers throughout the growing season to replenish nutrients that have been used up. Organic gardening expert, Steve Solomon, recommends a homemade fertilizer containing seed meal, agriculture lime, gypsum and dolomitic lime, with optional additions of bone meal, rock phosphate or high-phosphate guano, and/or kelp meal, along with regular applications of compost, for best results.
Liquid Fertilizer Feedings
Liquid fertilizers are used to fertilize seedlings started indoors, or for additional feedings throughout the season. Regular applications of fish emulsion or compost tea are excellent sources of nutrients and help seedlings get a good, strong start by replenishing nutrients in the soil. Compost tea is made by placing one quart of compost in a cloth bag and steeping in a gallon of water for several days. Other good liquid fertilizers include kelp meal tea and worm compost tea, made like compost tea, but with worm castings.
Foliar plant foods are sprayed directly onto plant foliage and absorbed, so that nutrients are available immediately. Compost tea, worm compost tea, kelp (seaweed), or fish emulsion are all foliar plant foods that are high in nitrogen and other nutrients that plants need.