Expanded Shale

It seems that we’ve been talking a lot lately about expanded shale. Actually, I’ve been banging that drum for over 20 years, so I’m still caught off guard when I’m asked what it is

Expanded shale, also known to some as haydite, is a lightweight aggregate. It is mined, crushed and fired under high temperatures in a rotary kiln to produce a clean, inert, porous, and lightweight material. In our crappy soils along the Gulf Coast, it is used to create pore space, and it’s an amazing amendment that’s great in landscape and vegetable beds and for planting trees and shrubs.

It’s often incorporated in various commercially available high-quality soils. The Arbor Gate’s Organic Soil Complete, for example, has a perfect amount.

Over the past two decades, I’ve found its greatest benefit is in helping big trees and shrubs get their roots established quicker. In my tip sheet for planting trees, I suggest it as a permanent soil amendment to help break up existing clay and give roots a hand in their first year.

Expanded shale also helps improve moisture retention in sandy soils. Thousands of tiny pores in the shale quickly absorb excess moisture. Then, then when things begin to dry out, the moisture is released back into the soil.And its moisture-absorbing benefit has given rise to its use in damp areas of turf or on gravel paths that are difficult to dry out.

You can buy it in bulk or bags. Some companies I endorse weekly on the radio show have it in bags as small as 8 quarts and as large as 40 pounds. Top Shelf Organic and Soil Mender products both offer it in smaller bags, and our local boys at Nitro-Phos have it big bags. If you need it in bulk, check out soil yards such as The Ground Up.

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