• The right fertilizer keeps plants productive.Garden image by TC from Fotolia.com
  
  Garden plants require a steady supply of nutrients to remain productive, whether you are growing vegetables or ornamental flowers. Fertilizer replenishes the nutrients in the soil throughout the growing season. Fertilizers provide nitrogen, phosphorus and potassium (N-P-K) to plants, along with several other trace nutrients. The correct amount of each nutrient depends on the particular plant's needs.
  
  

Soil Tests

• A soil test determines the acidity, or pH, of your soil and alerts you to any nutrient deficiencies in the garden so you can adjust your fertilization types and amounts as needed. Nitrogen is the one element not reliably tested. Garden centers often sell simple test kits or you can have a more in-depth soil analysis performed through your county extension office. You can start a garden without performing a soil test, but the test takes the guesswork out of fertilizer choices.
  
  

Organic Amendments

• Organic amendments, used alone or in conjunction with chemical fertilizers, provide additional nutrients to your garden beds. Compost provides organic matter, which leaches nutrients and improves the quality of the soils over time. Bonemeal, sometimes used as an organic substitute for the phosphorus in chemical fertilizers, provides calcium and phosphorus (P). Potash provides potassium (K), while manure and bloodmeal provide nitrogen (N). Apply organic amendments before planting garden beds.
  
  

Reading Fertilizer Labels

• Fertilizer packages have three numbers on them, which indicate the percentage of N-P-K in the bag. A 5-10-5 fertilizer provides 5 percent nitrogen, 10 percent phosphorus and 5 percent potassium. If plants have not come with specific recommendations, and you do not have recent soil test results, use a balanced or all-purpose fertilizer, which provides equal amounts of N-P-K (such as 10-10-10) for maintenance treatments.
  
  

When to Fertilize

• Many fertilizers have application amounts for a variety of plants listed on the bag. Generally, plants benefit from higher phosphorus early in the season, as this element helps them produce healthy roots and stems. More nitrogen toward midseason encourages healthy foliage and fruit production, though too much nitrogen can lead to lots of leaves but few flowers. Over-fertilizing is often more damaging than under-fertilizing. When in doubt about whether to feed garden plants, wait until plants become less productive before adding more fertilizer to the soil.