(Author’s note: I wrote this column last year but felt it was important to publish it again. The heavy rains we had last week washed through the soils and carried a lot of nutrients off as it went. The soil structure and textures may have been altered as well. It is important to make any needed soils corrections well in advance of planting to grow a successful garden.)
It does not matter if you are starting a new garden from scratch or are using a garden plot that has been there for years. The garden soil always needs your close attention.
Everyone who gardens wants to have healthy and productive plants. Healthy plants produce more and better fruit and flowers. To have healthy plants, you must provide a balanced diet of nutrients and water in the correct amounts and at the right time. This can be done without soil — called hydroponic gardening — but that is much too technical for most backyard gardeners. Most of us need to grow our plants in soil and that soil must be nearly perfect so we can realize the most our plants have to offer.
Garden soil is often overlooked as an important element in plant health. Soil is, without a doubt, one of the key components to a healthy garden. For plants to be healthy, they must have a healthy root system. The roots are where the plant collects the nutrients, water and oxygen that will be converted into food and which supports other life processes within the plant. In order for the plant to have a healthy root system it is vital the roots are growing in a healthy soil.
What constitutes a healthy soil? Precise specifications depend on the species of plant or plants being grown, but there are some general guidelines that apply to vegetables and most annual flowering plants.
Soil structure is important. It must be loose enough for the tender new roots to penetrate deeply in their search for nutrients. The soil must also be firm enough to provide physical support for the plants so they don’t fall over. Air and water must be able to penetrate easily down to a depth of 8 to 12 inches. A good soil will have a mixture of sand, clay and organic material.
Another type of soil is called loam. The particle sizes of loam are larger than clay and smaller than sand, and this also will be good to have in the mixture. To check the soil structure, grab a handful of damp soil and see if you can squeeze it into a ball. If you can, so far so good. Next, press your finger into the ball. If it falls apart easily then you have a good soil structure. If not you will need to think about amendments.
The soil must be able to hold water the plants can use as needed. However, too much water in the root zone will drown the plants or may provide an environment where root diseases can develop to destroy your plants. Sand will not hold water and clay will hold it too well. You need a well-drained soil that will hold the right amount of moisture. Organic material, such as compost or peat, improves the water retention in sandy soils and will also help with clay soils.
Organic material in the soil provides many benefits for plants. It can hold water for later use, prevent clay soils from becoming too hard and it will retain nutrients plants need to grow. It also serves as a food source for the thousands of microscopic organisms that live in soil. These little creatures break down the nutrients into a form that is easily used by the plants. The organic material needs to be replenished occasionally as it is used up by those little microbes.
Finally, it is important to get the soil chemistry right. Plants need nutrients. There are at least 18 elements that comprise the plants’ diet. Relatively large amounts of nitrogen, phosphorous, potassium, calcium and iron are needed. Relatively small amounts of other elements also are needed and some of these just barely need to be present in the soil. The amount of acid in the soil is also important as it affects the plants’ ability to absorb the nutrients through the roots.
Pretty much all of the garden plants we use in this area require a slightly acid soil. There is no way anyone can just look at the soil and determine if the chemistry is correct. The soil must be tested using reliable, scientific methods. Virginia Tech will test the soil for $10 per sample. Contact the Danville Extension Office at (434) 799-6558 for more information.
Right now is an excellent time to have the soil tested and to start working amendments into the soil. Don’t wait until planting time to show attention to this important detail.
Enjoy your garden.
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