WICHE: Plants grow in soil; dirt gets under your nails

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It is time to brush up on some garden nomenclature.

By Jeneen Wiche

With spring just around the corner, with my brain a little mushy from a long cold winter, I thought it was time to brush up on some garden nomenclature.

I have long been convinced of the value of understanding more about plants then the mere fact that they need sun, soil and water. The more we learn about what it is that plants need and how to determine if they are getting it, the more we will enjoy the act of gardening.

What exactly do I mean about “understanding more”? Things like tilth, loam and pH can make or break your azalea garden. Adding sulfur or lime can change the growing environment, for better or worse.

So how do we make sense of it all? Here are some important terms that many gardeners come across in their vegetable, perennial and ornamental garden endeavors. Some you may know, or not, and others may further clarify what might have gone terribly wrong when you dumped ashes around your azaleas.

Understanding some elemental gardening language may help you be a more responsible gardener – with plants that live longer, bloom better and produce higher yields. To wit:

  • Soil is pretty straight forward, but what makes up the mixture determines quite a bit. Soil is comprised of sand, silt and clay. These differences are basically because of soil particle size, with sand being large and gritty and silt being like talc. Typically, we are all faced with soil that is, in varying degrees, clayey. Adding sand and compost will improve the quality of heavily clay soil. The compost will add nutrients and the sand will allow for better drainage and aeration.
  • Loam is the term used to describe soil that has good proportions of sand, silt and clay and rich in organic matter. Loamy soil is ideal because the intermediate texture allows for good drainage and aeration. We all want loamy soil.
  • Tilth is the condition of the top layer of the soil. Having good tilth means that your soil is quite workable and crumbly. Bad tilth or no tilth is caused by compaction of the soil. By definition it is the physical condition of the soil and its ability to support plant life. Plants’ roots need water and oxygen, therefore crumbly lose soil is the good tilth because it allows for good drainage and aeration. This spring when you are ready to “work” the soil in your vegetable garden be sure the tilth is dry and crumbly before you do any digging. Working soil that is too wet, especially around here, will compact the tiny clay particles enough to make aeration and drainage even worse than it already is.
  • Average garden soil typically has a pH of about 7, meaning that it is neutral. Soil that is acid has a pH range of 4 to 6.5; alkaline soil has a pH over 7. Most plants do well in neutral to slightly acidic conditions with a pH of 6.5. All this becomes important because different plants enjoy different conditions. You’ve heard the term “acid-loving” plant applied to azaleas, rhododendrons, blueberries and hollies, for example. All of these grow best, stay greener, fruit and generally flourish in soil that has a pH 6.5 (and is well-drained). They cannot absorb nutrients if the pH is alkaline. Other plants, like cabbage, prefer a slightly alkaline environment, with a pH above 7.

So how do you know what your soil needs? A soil test kit can be picked up at you Shelby County Extension Service. You will be provided with the materials and instructions on how to prepare your sample properly. Return that sample to the Extension Service, and it will be analyzed for you. Once the condition of your soil is determined, you can add granular sulfur to reduce the alkalinity (to make it more acidic) or lime to make the soil more alkaline.

To improve the soil for plants that prefer slightly acidic soil you can add sphagnum peat moss, which not only has the same effect as sulfur, but it will also improve the texture of the soil.


Check out gardening columnist Jeneen Wiche’s work at www.SwallowRailFarm.com. You can find her columns also at www.SentinelNews.com/agriculture. She answers questions once a month in SentinelNewsPlus. To submit a question, send an E-mail to jwiche@shelbybb.netand type “Sentinel-News” in the subject field.