It's best to dig in your amendments in the spring before planting. Then roto-till the soil to fluff it up and make plant growth easier. Adding organic amendments to your soil will have long term benefits. In fact, the first few years you may not notice dramatic results. After the amendments have a chance to break down you should see the soil become darker, easier to work with, and require less watering.
Manure even has small amounts of plant nutrients.
Adding Fertilizer A garden should get regular doses of fertilizer to keep producing. That's because plants, rain and wind remove a lot of nutrients over time. Fertilizers come in both inorganic and organic forms. Phosphorous is crucial for flowering and fruiting plants. Potassium promotes the development of healthy roots and stems.