If you have a membrane under the gravel self-scattered seeds will be unable to grow, even if they germinate in the gravel, as they will be unable to put roots down into the soil.
A na-akpọ Ashen osisi na-enwusi onwe ya, n'ihi na ọ bụrụ na ị na-eweta egwuregwu na ifuru na ụbọchị ọkụ, ire ọkụ ga-enwu n'elu, osisi agaghịkwa ata ahụhụ.