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GARDENING TIP OF THE WEEK – OUR TOP 5 SOIL AMENDMENTS

Updated: Feb 15



5 SOIL AMENDMENTS EVERY NORTH TEXAN SHOULD USE

The soils of North Texas are both structurally unsuitable and notoriously poor in nutrients for growing anything other than weeds. Blackland prairie regions require clay-busting amendments. Long, dry summers call for moisture retention help. And so on. 

Use the time between growing seasons (August and January) to till in and/or top dress your beds with fresh organic material and other soil-enhancing amendments. Here we present our 5 favorite soil amendments along with their benefits.

Organic Compost



Good quality compost should not smell bad, just earthy. The consistency should be loose and crumbly.

Organic compost can dramatically improve poor soils. Sandy soils suddenly soak up and hold more water. Brick-like clay is transformed into soft, workable earth. Even well-worked soils benefit from a fresh layer of compost each season. 

Compost-amended gardens are more resistant to diseases, and also tend to have fewer pest problems, according to Gardening Know How, which means they require fewer pesticides. In addition, compost that is predominantly leaf based, has been shown to be effective against nematodes, and compost application to grass suppresses a multitude of fungal diseases.

There are essentially four ways to use compost. One is to work it into the soil of flowerbeds, vegetable gardens, and other planting areas. Another is to apply compost as a “top dressing.” Adding a 1/2-inch to 1-inch layer of compost makes a great fertilizing mulch that slowly releases nutrients to your plants and helps protect them from temperature extremes, moisture evaporation and soil erosion. Try applying a layer to your lawn to help reduce soil compaction and fertilize grasses. Still another use is as potting soil for container plants.

Our customers often ask us which compost is the best. The answer is a bit tricky because when it comes to your soil, bio diversity is beneficial. So, for example, if you used a turkey compost in the spring, you might want to use a mushroom compost in the fall and a cow-manure-based compost the following spring. What’s important is that the material be slow-composted to achieve a high temperature, which ensures that no pathogens remain in the finished product.

Expanded Shale



Expanded shale is a by-product of the oil drilling process. The rock is fired in a kiln at high temperatures, which cause the shale to fracture. As the material cools, cavities are left after gases escape, leaving a porous lightweight chunk capable of absorbing water and releasing it slowly at a later time.

Expanded shale opens up and aerates heavy, sticky clay soils faster than any other material available — an ideal amendment for Texas gardens! Expanded shale is shale that has been kiln fired, causing it to expand. As it cools, gases escape leaving cavities in the material. The result is a more porous and light weight rock capable of holding water, which it can then release slowly into the ground. In this way, the shale helps keep your soil moist longer. Another benefit of expanded shale is that it is 100% recycled material — a by-product of the oil drilling process, expanded shale helps reduce waste.

The Texas Cooperative Extension recommends putting down 3 inches of expanded shale on top of the area, and tilling it in six to eight inches deep.

Lava Sand



Lava sand is crushed red lava rock, a highly porous volcanic material that helps with moisture retention and microbial activity.

Lava sand is crushed scoria, a porous, reddish brown to black volcanic slag. It has water-holding properties similar to expanded shale, with the additional benefit that the particle size is much smaller. Garden IQ explains that lava sand is also highly “paramagnetic,” which, in layman’s terms, means it attracts electricity. Why is that important? Paramagnetic energy improves microbial development and the resulting plant growth. In gardening terms, lava sand makes soil nutrients more available to plant roots loosens the soil and helps retain moisture.

Texas Green Sand

Texas Green Sand is an exceptional soil conditioner for pastures, forage fields, lawns, orchards, small fruits, vegetables and greenhouse potting mixes. It’s loaded with minerals that your vegetables soak up and pass on to you when you eat them. It’s also another great product for breaking up clay soils.

According to Garden.com, green sand is one of the oldest and most generally useful tools in the organic gardening tool box. Green sand has been used since the 18th century as a soil amendment and slow-releasing fertilizer (0-0-3). It is one of the best certified organic sources of potassium. Mined from sediment that once rested on the ocean floor, it contains a high percentage of the mineral glauconite (greenish-black to blue-green). Glauconite is primarily potassium, but it also contains iron, magnesium, calcium, phosphorus and about 30 other trace minerals your plants need. These minerals are released slowly and gently , says Gardening Know How, which protects plants from the classic root burn that many stronger fertilizers can cause. 



Texas Greensand is crushed glauconite, a mineral-rich marine deposit.

Glauconite acts as a water softener. Why should this matter to your plants? Because when soil is poor, it will often develop a layer of crust on top. This is the result of dissolved metals in the ground. Not only does the crust make the soil difficult to work, it also prevents water from soaking in and plants from sprouting. The crust comes from positively charged ions that migrate out of the surrounding earth. Green sand prevents dissolved calcium, magnesium, manganese, and iron from getting loose — it keeps them in the ground and accessible to plant’s root systems.

Apply three pounds per 100 square feet at the start of the growing season. To recondition soil, add up to 40 pounds per 100 sq. ft.

Mycorrhizal Fungi

Healthy soil is also full of fungus. As yucky as this might sound, several types of fungi aid plants in their efforts to soak up nutrients. In healthy soils, mycorrhiza is a naturally occurring fungus known to aid in the uptake of nutrients. Scientific trials have documented significant improvement in the establishment of roots and subsequent growth by inoculating the soil or planting medium with mycorrhiza.

Mycorrhizal fungi greatly enhances plant growth, vigor and tolerance of environmental extremes. They colonize roots and extend into the surrounding soil to form an essential link between plant and soil resources, greatly increasing the root’s ability to absorb water and nutrients, while improving plant yields and health. When you add Mycorrhizal fungi to your soil, your goal should be to create physical contact between the roots of your plants and the fungi. It can be banded under seed, worked into seed beds, placed under cuttings, blended into potting soil, or sprinkled near roots at transplant time.

The Texas Agricultural Extension lists many benefits of Mycorrhiza:

  • Enhanced plant efficiency in absorbing water and nutrients from the soil.

  • Reducing fertility and irrigation requirements.

  • Increased drought resistance.

  • Increased pathogen resistance/protection.

  • Enhancing plant health and vigor, and minimizing stress.

  • Enhanced seedling growth.

  • Enhanced rooting of cuttings.

  • Enhanced plant transplant establishment.

  • Improved phytoremediation of petroleum and heavy metal contaminated sites

  • Produces more stress resistant plants during production and for landscape

  • Potentially less pesticide usage.

  • Plants are more drought and nutrient tolerant in the landscape.

  • Potentially higher transplanting success and faster establishment.

Visit our Soil Amendments web page for more information on these and other soil amends we stock. Or stop in the store and talk to one of our gardening experts.


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