I have suckers growing from a 7-inch diameter root. This root is only 1 inch below the surface. I have mounted soil/compost around the bottom of the suckers to induce rooting but was unsuccessful. I also air-layered a sucker in May which died after 4 months. Usually a sucker will root if the root it grew from is cut but because the suckers are growing off a large root I cannot do this. My intention is to get rootstocks for grafting. What should I do? Please advise.

Thank you.

Sengyan