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Understanding Your Soil

Having great soil should be the basis of all your gardening. Once you conquer the "whys" and "wherefores" of the earth beneath your feet you are on way to successful gardening.

Deciding where you are to garden might be the most important decision you have to make in the entire process. Where you decide to locate the vegetable garden or flowerbeds will decide whether your plants will be most happy. Planting just outside the kitchen door, near the back of your property, on the side of the house, or maybe 2 miles away - wherever you decide will be a big factor in location success.

Vegetable gardening requires a good solid six hours of sunlight. This is necessary for full production. Without this, you will be forever struggling.

Nutrients and Micronutrients

All soil requires three important nutrients. They are nitrogen (N), phosphorus (P), and potassium (K) These three elements directly help in the plant development. Nitrogen is for stem and foliage growth - dark green leaves and lush growth. Phosphorous helps the growth of roots and blooms - flower and seed production. Potassium will create strong stems and roots. If any of these three are missing the plants will not grow or function.

When you buy a bag of commercial fertilizer you will find three numbers on the bag: 10-10-10- or 10-6-4. Fertilizer comes in a variety of combinations. This is the NPK rating. The first number always indicates the percentage nitrogen (N), the second stands for the percentage of Phosphorous (P), third is the percentage of potassium (K). These are the chemical symbols used internationally.

A "blooming" fertilizer is one with a high middle number (phosphorus). Examples of blooming fertilizers might be 10-50-10 or 10-60-10.

Not only are the three major nutrients required but micronutrients as well (see article).

To see if your soil is good, do a soil test. Your county extension office provides this service. A small fee may be involved. The extension office may do the test themselves or send the sample off to the land grant university of your state. Oftentimes nurseries will provide soil testing.

There are several methods of taking a soil sample. Digging down six to eight inches and taking many samples from many spots will give you a more complete picture of your area.

pH value

The results of your soil sample will also indicate a pH value. Plants respond directly to a pH level. A soil reading with a pH that is high will be alkaline. A low reading will be acidic. Most plants are happy with neutral pH with a value between 6.0 and 7.0.

There are generalizations about what your pH might be. High rainfall generally produces acidic soil (you've heard of acid rain?). The southeast part of the country generally has acidic soil (from all of the pine forests?) but Florida generally has alkaline soil because of the limestone deposits. In order to know for sure, you should test.

While most plants like a neutral soil, there are exceptions. Roses like slightly acidic soil. pH values between 6.0 - 6.5 are best, but they will grow in pH up to 7.5. Holly, Azaleas, and Rhododendrons like even more acidic soil (between 4.5 and 6.5) as well as most fruit (6.0 - 6.5). Blueberries like the most acidic soil (4.0 - 5.5). If there is a question about what your pH should be for your plant, find out for sure what your specific species likes.

If your pH is way out of line (below 5.8 or above 7.0) you can add material to compensate.

Lime is suggested for raising the pH (to make the soil less acidic or more alkaline). Ten pounds of lime will raise 100 square feet of soil one point. Mushroom compost will also raise the pH.

If you need to lower your pH (to make the soil more acidic) you can add pine needles. Ammonium sulfate will also do the trick.


When adding organic matter to the soil it will not only add some nutrients, the structure of the soil will also be improved. Sandy soil will begin to retain moisture and clay soil will begin to break down and become crumbly. Leaf mold, compost, and any well-rotted manure are all good organic sources.

Your soil will benefit the most by full application of amendments. The winter rains and the freezing and thawing of soils will help to aerate the soil.

Do not work your soil too early in the spring. Squeeze a ball of soil and if it crumbles, it is ready when you are.

Your gardening success depends on your soil and how you treat it.

Good luck and respect the earth.