Q: How many citronella plants are needed for maximum mosquito protection in a backyard?

A: Despite the claims, citronella plants do not repel mosquitoes. Citronella grass, Cymbopogon nardus, and citrosa (scented geranium) contain citronella oil, which does repel mosquitoes. However, the plants don’t release enough oil into the air to repel insects. You could crush the leaves and rub the juice on your skin but you might get an allergic reaction from other components of the sap. On a deck or patio, a raised oscillating fan can protect a large area. Otherwise, applying mosquito repellants that contain DEET, picaridin or oil of lemon-eucalyptus to exposed skin is best.