Since most organic gardening is based on conditioning the soil long term, preparing your soil now in Fall is wise as well as a time saver when Spring comes. I follow the philosophy, feed the soil, not the plants. There are occasions when giving your plants an additional feeding boost is smart such as when you transplant seedlings or move plants to a new location, but in general taking steps to have nutritious soil from the start will assure healthy strong productive plants.
Organic fertilizers generally come from plants, animals, or minerals. Soil organisms break down the material into nutrients that plants can use. Some organic fertilizers contain significant amounts of only one of the major nutrients, such as phosphorus in bone meal, but they often have trace amounts of many other beneficial nutrients. In addition, we add organic material that improves soil structure and supports soil microorganisms, which helps make nutrients available more quickly, especially in warm weather when they are more active. As a general rule, organic fertilizers release about half their nutrients in the first season and continue to feed the soil over subsequent years.
Fertilizers made from plants generally have low to moderate N-P-K (nitrogen, phosphorus, potassium) values, but their nutrients quickly become available in the soil for your plants to use. Some of them even provide an extra dose of trace minerals and micronutrients. If you don't find all of these at the garden center, check out your local feed store. The most commonly available plant-based fertilizers include the following:
Most animal-based fertilizers provide lots of nitrogen, which plants need for leafy growth. The following are some of the most commonly available ones:
Rocks decompose slowly into soil, releasing minerals gradually over a period of years. Organic gardeners use many different minerals to increase the fertility of their soils, but it's a long-term proposition. Some take months or years to fully break down into nutrient forms that plants can use, so one application may last a long time.