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There is much more than meets the eye when it comes to your soil. No matter how much work you put in as a gardener, you’re not going to have much luck without healthy soil and understanding what you are working with. 

Let’s start by getting the dirt—What makes it tick? What drains it? How can you help it thrive? We will answer these questions, and many more, in this guide to understanding what’s in your landscape.


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The Different Soil Types/Classifications 


Soil is composed of layers or horizons. In the natural world, these layers build over time, leaching nutrients down to create healthy, living soil. In reality, most of our surrounding city soils have been disturbed due to development. Much of their natural layers have been scraped away and nutrient-deficient topsoil has been brought in to replace it, creating a subpar growing environment. 

There are six main soil classifications—clay, chalk, silt, sand, peat, loam—and they all have important functions in your landscape. Their properties vary, and while some may not seem ideal, there are ways to improve them all! But first, we must know what it is we have in our own backyards.


meyer landscape design understanding soil types red clay soil


Clay—The most common soil type here in Iowa. Clay can be nutrient-rich, but also heavy and poorly-draining; this can suffocate many delicate root systems if not amended. Clay is made up of tiny mineral particles that don’t have air spaces between them, causing poor drainage. When wet, it remains waterlogged, and it dries and cracks during periods of drought. Both situations are not ideal for our trees, shrubs, and perennials. Clay does best when amended with a combination of compost, sand, gravel, and gypsum.

There are six main soil classifications—clay, chalk, silt, sand, peat, loam—and they all have important functions in your landscape.

Chalk—This type is very alkaline, meaning it has a very high PH, which can inhibit plant growth and cause nutrient deficiency. As expected, chalky soils don’t tend to hold water well and dry out quickly. These soils are better once amended with compost, peat moss, and sulfur.


meyer landscape design understanding soil types silty soil


Silt—This type has slightly larger particles than clay. It is often soft, smooth, and tends to retain moisture quite well, but it is also well-draining. Considered to be one of the most fertile soils, it is ideal for growing crops. Although silt is ‘better’, we still suggest amendments of compost and other organic matter to improve soil structure and nutrient levels.

Sand—Also referred to as ‘light soil.’ This classification tends to be warm, dry, acidic, and often nutrient-deficient. It is easy to work with and warms up relatively quickly in the spring, but it will most definitely require some amendments if you want to use it as a growing medium. We suggest a combination of compost and vermiculite to improve water retention, structure, and nutrient levels.

Peat—While it is made primarily of organic matter, allowing this soil type to retain quite a large amount of moisture, peat is highly acidic and retains very few nutrients. Peat naturally occurs in bog environments and is generally missing from gardens. It is brought in to add and amend the base. 

Loam—Basically the creme-de-la-creme of soil classifications, this is a perfect mixture of sand, silt, and clay. It tends to be nutrient-rich, drains well, and retains moisture well. 


meyer landscape design understanding soil types testing small soil sample


How to Determine What Kind of Soil is in Your Garden


Your landscape is likely a unique combination of the different types we have listed above. Aside from recognizing some of the basic characteristics, there are a few different ways to figure out what kind of soil you have. The first is a squeeze test. Take a handful when moist (not soaked) and rub some between your fingers. What do you feel? If it’s primarily slimy, you probably have a heavier balance of clay. If it feels gritty, likely, you have more sandy soil. 

There is also the jar test which, while not exactly scientific, tends to be a little more accurate. Dig a small hole in your landscape, about twelve inches deep. Gather the soil and place it in a large glass container. Then, fill half the jar with water, shake it, and let it settle for about two hours. The heavier particles (the clay) will fall to the bottom, the silt will rest on the clay, and the sand on the silt. Once everything settles, measure the height of each layer, and divide each of them by the total height in the jar. Voila! You have a small-scale replica of your soil type!

Now that you have an idea of the make-up of your landscape, it’s time to test the pH. Head to our garden center to grab a pH test kit. At this point, you should have a pretty accurate understanding of what you are working with and what your landscape is missing.


meyer landscape design understanding soil types amendments vermiculite perlite


Amendments to Improve Your Soil


Regardless of what you are working with, adding compost is a given! Compost consists of decomposed organic matter, and you can’t find anything better to improve the health of your soil. It helps retain nutrients and moisture, improve the overall structure, promote better drainage, and helps to maintain a neutral pH level (which is ideal). 

Additional amendments like vermiculite and perlite can also help loosen compacted soil, improve drainage and retain moisture. Vermiculite is particularly effective at conserving moisture, and perlite is particularly effective at improving drainage.

Mulch, like compost, is helpful for all landscapes. In the case of clay, if you add a thick layer of mulch in the fall and leave it over winter, you can till it into the soil in the spring to help promote drainage. If you have too much sand, a thick layer of mulch applied in the spring will enable your soil to retain more moisture. 

Once you have a solid understanding of your soil, you’ll be nearly unstoppable as a gardener! It puts you in a position to choose plants that will thrive in your particular landscape and make your gardening experience more enjoyable! If you’re wondering where to buy good garden soil, amendments, or soil tests in the Quad Cities, stop by our garden center. We’d be happy to get you all stocked up and answer any more burning questions you might have.


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