If you want to get a bit savage removing the plastic, but are afraid of damaging the
plant roots, Get a bottle of seaweed 'juice'. Rip away the plastic like crazy, then when you've finished, chip out any
weeds which remain and give the area a good soaking. You can leave the
weeds where they fall. Then apply the seaweed juice at the recommended rate. Add some organic all purpose fertilizer like pelletised chicken manure and mulch the area. Water again. Any damage you do to the roots will be minimised by the seaweed and any new growth you knock about will be quickly replaced. Do it once, do it properly:-)