Fertilizer Facts

Learn key basics about fertilizer that will help you select the right type based on your soil composition and growing conditions.
Joe Lamp'l offers valuable info about fertiliz

Joe Lamp'l offers valuable info about fertiliz

There are three main nutrients found in fertilizer, each with its own special benefit. Consequently, there are three main numbers you'll find on a fertilizer bag -- in order: nitrogen, phosphorus and potassium; they're listed in alphabetical order.

  • Nitrogen is the first number on the fertilizer bag and it just may be the most important. Nitrogen is one of the most common elements and it's critical to all forms of life, especially plants. Nitrogen is what makes plants have healthy green foliage. Too little nitrogen and plants look anemic and lack full leaves. Too much nitrogen in the garden and your plants will be all leaves and stems and no fruit.
  • The second number on a fertilizer bag stands for phosphorus. Phosphorus is critical in the development of blooms. Since each bloom becomes a fruit or vegetable, it's very important in the garden. Tomato plants need phosphorus to have larger and more uniform tomatoes. Annual or bedding plants bloom only when there is enough phosphorus in the soil. Most gardeners add rock phosphate to their garden since phosphorus is often lacking in most soil types.
  • The third number on the fertilizer bag represents potassium. Plants that are low in potassium may look weak or thin and may have fruit that doesn't fill out completely. Potassium helps the main systems of the plant function together, helps with photosynthesis and controls the exchange of carbon dioxide. Green sand and wood ash are full of potassium that can be easily absorbed by plants. These can burn plants if added too closely so follow the instructions on the package for best results.
  • Almost all fertilizers have micronutrients. These are elements that are important to plant growth, but are needed in much smaller quantities than nitrogen, phosphorus and potassium. The main five are magnesium, copper, iron, manganese and zinc. You'll see on the label that they come in fractions of a percent. These nutrients add to the fertility of the plant, help with fruit production, and make plants more resistant to pests and diseases.
  • Slow-release fertilizers are a safe and easy way to feed your plants. The slow release coating means the nutrients are broken down over time so the plant won't get burned. This type of fertilizer works because the granules only break down with water and heat. As you water and as your garden soil warms up, your garden plants grow faster, just in time to absorb the fertilizer as it's released into the soil.
  • Liquid fertilizers are a great supplement to granular fertilizers. They give plants a quick boost because the nutrients are absorbed right into the leaves. They're helpful with plants that are suffering from lack of nutrients and they make healthy plants much more productive. Excess fertilizer drips from the leaves down the ground below. Because liquid fertilizers are absorbed by the roots as well as the leaves, none of the nutrients are wasted. Be sure to follow the directions carefully to get the proper water to fertilizer ratio.
  • Organic fertilizers are another useful tool for improving soil nutrition in the garden. Fish emulsion is used as a foliar or leaf spray to add nitrogen to a plant. Bone meal is what the name implies and is a powder that is added to the soil. Cow manure is an organic fertilizer than can be purchased in a bag form your garden center. Be sure to understand the proper use for any fertilizer you add to your garden.

 Ask a garden expert for advice if you're unsure which product is best for you.

Keep Reading

Next Up

Incorporating Vegetables Into Flower Beds

If you're limited on space for a vegetable garden, incorporate veggies into existing flower beds.

Mulch Options

Find out the different benefits of various types of mulch and determine which type is best for your garden.

How to Plant and Grow Peas

To be a successful backyard pea farmer -- and picker -- follow directions, keep the birds away and feed the soil.

Quick-Growing Spring and Fall Vegetables

From seed to dinner table in one month? These quick-growing vegetables give the garden a good start and a lingering end.

Tips for a Raised-Bed Vegetable Garden

Raised-bed vegetable gardening takes very little space and allows vegetables to be grown closer together.

Soil Preparation

Organic amendments will help correct soil deficiencies in a new garden plot.

Organic Plant Health Care

Learn how to add some compost and compost tea to organic plants instead of fertilizer.

Organic Garden Additives

Instead of using store-bought chemicals, organic gardeners take a simpler approach to fertilizers, pesticides and fungicides. Effective versions of each can be mixed up using ingredients already close at hand and a basic kitchen blender.

The Benefits of Compost

Often called "black gold," compost is valued for giving plants a boost when added to the soil of garden beds. Learn how to give your compost pile the jumpstart it needs.

Fertilizer Tips

Fertilizer is key to full and healthy grass. Here are some basic tips about fertilizing.


Big Beach Builds

7:30am | 6:30c

Big Beach Builds

8:30am | 7:30c

Big Beach Builds

9:30am | 8:30c

Big Beach Builds

10:30am | 9:30c

Big Beach Builds

11:30am | 10:30c

Rehab Addict

12pm | 11c

Rehab Addict

1pm | 12c

Rehab Addict

1:30pm | 12:30c

Rehab Addict

2:30pm | 1:30c

Rehab Addict

3:30pm | 2:30c

Rehab Addict

4:30pm | 3:30c

Rehab Addict

5:30pm | 4:30c

Rehab Addict

6:30pm | 5:30c

Rehab Addict

7:30pm | 6:30c
On Tonight
On Tonight

Pool Kings

8pm | 7c

Pool Kings

8:30pm | 7:30c

Pool Kings

9pm | 8c

Pool Kings

9:30pm | 8:30c

Pool Kings

10pm | 9c

Pool Kings

10:30pm | 9:30c
11pm | 10c

Pool Kings

12am | 11c

Pool Kings

12:30am | 11:30c

Pool Kings

1am | 12c

Pool Kings

1:30am | 12:30c
2am | 1c

Pool Kings

3am | 2c

Pool Kings

3:30am | 2:30c

Garage Gold

4:30am | 3:30c

Get Social With Us

We love to DIY. You love to DIY. Let's get together.

Consult Our A-Z Guide

Everything You Need to Know

Browse a full list of topics found on the site, from accessories to mudrooms to wreaths.  

How-To Advice and Videos

Get video instructions about kitchens, bathrooms, remodeling, flooring, painting and more.

Watch DIY Downloads Now

Watch DIY Network LIVE

Don't miss your favorite shows in real time online.