The Groasis technique is based on not destroying the capillary soil structure; so, normally, the planting hole is a maximum 10 cm deep. However, there is one situation in which there is no capillary structure. That is when there is a limestone layer in the soil. In some countries this is called “hardpan”, “duricrust”, “kankar” or “calcrete”.
This layer is so hard that water cannot pass through it. This means that water cannot evaporate through it, and rainfall also cannot pass through it into the soil. Just as with water, the same is true for roots of the trees that we plant. This means that if there is a hardpan, one should break a surface area of around 1 m2 - but not go deeper than the hardpan.
Leave the normal soil or rocks under it intact. If one has to plant bigger areas and there is a hardpan, it is better to use the capillary drill. Plant the tree, then add the Groasis Waterboxx® plant cocoon over the top of the tree, which immediately gives assistance and will allow your tree to grow.