Holmes was educated at the Grammar School in Boston, Lincolnshire and the Grammar School in Wimborne Minster. At the age of 14 he was apprenticed to Mr. S. S. Hayward, a pharmacist in Cheyne Walk, Chelsea, London. He studied pharmacy at the Pharmaceutical Society's school in Bloomsbury Square, walking from Chelsea to attend morning lectures. He passed the Minor examination to qualify as a Chemist and Druggist. He then worked for Mr T.Vicary in Plymouth, and while there collected a herbarium of British plants which won the Society's bronze medal in 1863. He passed the Society's Major examination to qualify as a Pharmaceutical Chemist in May 1864.
