The citronella plant is native to tropical climates, so while it can return annually in cooler regions, it will really flourish if planted after the last frost of the year — about the same time that you would plant your tomatoes. Wait till the ground warms up and plant it in loamy soil with a pH of roughly 6.5 to get your citronella off to the start it needs.

The citronella is a bushy plant, so if it's doing well, it will need plenty of space to spread. A plant can reach six feet tall and six feet wide if cultivated under ideal conditions, and while many gardeners recommend spacing them 18 to 24 inches apart, doing so could result in a very dense citronella patch. Plant them a bit farther apart if you expect them to thrive, to mitigate overcrowding.

The citronella plant is hardy in growth zones 10 to 12, which correspond to the warmer climates of the south. It can grow in cooler temperatures, but will usually be an annual rather than a perennial. In either case, the citronella prefers indirect sunlight with enough shade to keep its leaves from scorching.

With its origins in subtropical regions like southeast Asia, it comes as no surprise that the citronella requires a significant amount of water. Daily hydration is a must for these plants, so be sure to give them a drink once the top inch of soil has begun to dry.

The citronella's fame lies in its insect-repellent properties, as its citrusy scent confuses and repulses mosquitoes. It makes sense, then, that this plant faces little danger from other invaders. If you purchase citronella plants in the hopes of fending off undesirable insects, know that their defensive properties help only themselves when they're planted — they won't keep bugs away just by sitting there. You must apply their oil to the skin or clothing or release it by burning to get the repellant benefits.

In the same way that the citronella's oils make it offensive to pests, there are also very few diseases to which it is vulnerable. Root rot can endanger citronellas if they have poor soil drainage, but proper aeration can nip this affliction in the bud.

Although the citronella is a hardy plant, extra nutrients always help. Start out with a one-inch layer of rich organic compost to give it the head start it needs, and feed it with liquid fertilizer of a 5-10-15 NPK ratio. An annual boost of nitrogen-rich fertilizer will also give it a boost.

On top of its usefulness as an insect repellant, citronella benefits humans emotionally and physically. Its refreshing fragrance can treat anxiety, and it also serves as an antifungal and antimicrobial disinfectant — hence its use in Asian countries as a soap and cleaning agent. Citronella has also been used to treat lice and intestinal worms and has anti-inflammatory benefits.