The most common ingredient in many mosquito repellents comes from citronella. A large clumping grass that grows up to 6 feet tall, citronella is a perennial plant that can be grown in large pots or raised planter beds. It also thrives when planted directly in the ground in areas where frost does not occur.
Catnip is also effective in repelling mosquitoes and is very easy to grow, though it only works in close proximity. Crushing up the leaves to apply catnip oil provides better protection than some commercial repellents. A study by Iowa State University found that catnip is more effective than the chemical repellent DEET found in most commercial products. The plant is not advised for use by cat owners, as using the oil or handling the plant frequently still affects felines.
Flowers such as marigolds and ageratum emit odors while they are in bloom, which mosquitoes find offensive. Both types of flowers contain compounds that are found in insect repellents. Lemon balm, peppermint and chamomile are also known to repel mosquitoes and many other flying insects, and they can be used in cooking and herbal teas. Horsemint, a perennial and hardy flower, grows quickly and tolerates shade and dry conditions. It produces a scent that confuses mosquitoes while still attracting butterflies and bees that benefit gardens.