The citronella plant, often referred to as citronella geranium (Pelargonium citrosum), is a fragrant, leafy plant known for its fresh lemony scent. It’s popular on patios and in gardens for its natural mosquito-repelling properties. The plant releases citronella oil from its leaves, which can help mask scents that attract mosquitoes. While simply growing the plant nearby may offer some mild deterrence, its effect is strongest when the leaves are crushed to release the oils.