Mr Hoare was identified as the UK's oldest active gardener by retailer Furniture Village which led a hunt for an expert to respond to the nation's horticultural questions.
Thegardener had pointed to a thick bamboo stem and explained that if a pebble was thrown at it and it hit the trunk slightly off-centre, it would bounce off and make hardly any sound.
Gardener and tutor Alys Fowler said no previous professional gardening experience was necessary as, for her, the ideal volunteers would be office workers.