Organic fertilizers and amendments release nutrients slowly and improve soil structure over time. They work best when combined with a soil test, since too much of any nutrient can cause problems. This guide covers the common options.
Start With a Soil Test
A soil test shows pH and nutrient levels, so you apply only what is needed. Your state university extension service can process samples for a modest fee.
Common Organic Options
- Compost: improves structure and adds a broad range of nutrients.
- Well-rotted manure: adds nutrients and organic matter. Use aged manure, since fresh manure can burn plants and carry pathogens.
- Blood meal, bone meal, and feather meal: quick-acting or slow-release nitrogen and phosphorus sources.
- Kelp and fish products: provide micronutrients and can support soil life.
Timing and Application
Work compost into beds before planting. Side-dress heavy feeders, such as tomatoes and squash, once they begin to grow vigorously. Avoid heavy feeding late in the season.
Avoid Overapplication
Organic does not mean unlimited. Excess phosphorus and nitrogen can run off into waterways and harm plants. Follow soil test recommendations.
