THE BEST HERBS FOR CLEANING

Many herbs have potent disinfectant properties, but some are more powerful than others. In one Australian study (published 1999), 52 plant oils and extracts were tested against 10 microorganisms, including E. coli, salmonella, candida and staph. The top-performing herbs included bay, lemongrass and oregano, which inhibited all organisms at concentrations of less than or equal to 2 per cent. Rosewood, coriander, palmarosa, tea tree, niaouli, peppermint, spearmint, sage and marjoram inhibited all organisms except the common Gram-negative bacterium Pseudomona aeruginosa at less than or equal to 2 per cent. Six oils – pumpkin, macadamia, evening primrose, apricot kernel and sweet almond – and the essential oil clary sage, failed to inhibit any organisms at the highest concentration, which was 2 per cent. Myrrh and cypress inhibited Gram-positive organisms only, while carrot, patchouli, sandalwood and vetiver inhibited Gram-positive bacteria and Candida albicans only. Mandarin oil inhibited Candida albicans at 2 per cent, while bacteria were not inhibited at less than or equal to 2 per cent. None of the oils inhibited Gram-negative bacteria only.

Two lavenders were tested, one sourced from France and one from Tasmania. The results differed. When tested against E. coli, the French sourced lavender inhibited this microorganism at a 0.5 per cent concentration while the Tasmanian sourced lavender inhibited it at 0.25 per cent. For many of the other microorganisms lavender was tested against, the rate of inhibition for both lavenders was greater than 2 per cent.