A plant 103 is grown permanently in a planting container 90 alongside at least one root ingrowth container 22, 24 which occupies a substantial volume of the planting container. Each ingrowth container has a perforated wall (3, figs 1-4) through which roots 100 grow into an ingrowth cavity. An extraction tool 30 is inserted into the open end 5 of one of the ingrowth cavities and a cutting head 40 with a lead screw is operated to extract roots 100 and growing medium 110. The cavity is then refilled with fresh growing medium so that the roots can re-grow. By refilling the ingrowth cavities in rotation fine roots continually develop in renewed soil. The containers may be integral. The ingrowth container may be ceramic or steel in a range of specified sizes with a defined bursting pressure and crushing pressure.
