Expanded Shale

Photo Credit: Randy Lemmon

Does it seem we’ve been talking a lot these days about Expanded Shale?! We have! And even though I’ve been banging that drum for over 20 years, it still catches me off guard a time or two, when a caller, or say a visitor at a public appearance, looks at me quizzically, and asks… “What’s expanded shale?”

Expanded Shale is a lightweight aggregate. The shale is mined, crushed and fired under high temperatures in a rotary kiln, producing a clean, inert, porous, and light material. It’s also known as Haydite in some circles.  It’s incorporated into several types of high-quality soils.  For example, The Arbor Gate’s Organic Soil Complete has a perfect amount.  

The most important thing it does for us along the Gulf Coast, and in our otherwise crappy soils, is to create pore space. It is simply an amazing “soil amendment” that is great for amending beds (landscape and vegetable), and planting trees and shrubs.  Expanded Shale’s greatest attribute for us, especially the last couple of years, may be its ability to absorb excess moisture. More on that in a second.

Meanwhile, my favorite benefit for expanded shale for the past 2 decades has to be how it helps big trees and shrubs get their roots established quicker. If you’ve ever seen my tip sheet for “Planting Trees” it has always suggested as a permanent soil amendment to help create that pore space or break up the existing clay soil in such a way to give the root systems a helping hand in getting established within the first year.

Besides the much-needed porosity the Expanded Shale provides, this soil amendment helps improve moisture retention in sandy soils. The thousands of tiny pores in expanded shale quickly absorbs excess moisture, and then when things begin to dry out, it releases it back to the soil. And because of that ability, and as I noted earlier, the moisture-absorbing benefit has given rise to using this product in damp areas of turf or gravel paths, that have difficulty drying out at a normal rate.

You can buy it in bag or in bulk. Companies you hear me endorse every weekend on the radio show, have it in bags. However, if you need it in bulk, most soil yards can provide that service easily these days.