How to Add Nitrogen to Vegetable Gardens


The most abundantly used nutrient in your garden bed is nitrogen. Microorganisms need it to break down decaying matter and plants need it to make chlorophyll, the food plants "eat" to grow to maturity. Adding nitrogen, if needed, to your garden space before planting should be considered one of the first chores of preparing for the growing season. By understanding how this mineral is used, you will have better results each year.

Step 1

Cut down into the ground with a clean hand trowel and pull out a three-inch sample of soil. Try to get your sample away from any decaying plant matter like leaves or bark mulch, as these will skew the test results. Package up the sample in a clean container and take to your local agricultural extension office for free testing. They will be able to help you determine the amount of nitrogen and other nutrients needed to return your soil to the correct growing balance.

Step 2

Purchase fertilizer in the correct nitrogen ratio as determined by your extension office. Most fertilizers are manufactured in a nitrogen to phosphorus to potassium balance. The numbers on the package will show something like 10:10:10, showing the ratio per pound in the packaging.

Step 3

Spread fertilizer as per the brand's instructions--most of the time by the shovelful first into the soil, turning it over into the dirt about a foot to 18 inches down; and then, working the soil to a powder consistency with the tiller.

Step 4

Plant your seeds and plants as usual.

Tips and Warnings

  • If you chose to compost in the garden, you must add nitrogen on a regular basis. While a decent source of nitrogen once finished, compost, in its decaying form, must have microorganisms eating away at it. Those microorganisms need an enormous amount of nitrogen to accomplish this. For best results, compost in a bin or pile in the corner of your garden instead of adding yard waste and food scraps to your garden. Mulch vegetable gardens with compost or straw instead of bark mulch. Again, bark mulch will break down and soak up nitrogen from the soil, away from your plants. When applying nitrogen, keep the mineral out of the section of garden reserved for plants like tomatoes and squash--unless you want big, gorgeous plants with no yield. Nitrogen aids in the growth of greenery and a steady supply will keep the plant from producing fruit.

Things You'll Need

  • Hand trowel
  • Clean, small container
  • Fertilizer in the recommended ratio or compost
  • Shovel
  • Tiller or hoe


  • Colorade State Extension: Fertilizing the Garden
  • Minnesota Master Gardener: Mulching the Garden
  • Organic Gardening: Soil Nitrogen Content

Who Can Help

  • USDA: Finding Your Local Cooperative Extension Office
Keywords: fertilizer, manure, compost

About this Author

Bobbi Keffer attended Kent State University, studying education but soon found her true love to be in the garden. She prides herself on her frugal skills, re-using, recycling, and re-inventing her whimsical style in her home and garden.