About Pelargonium ‘Citrosum’

Description

The citrosa or citronella plant is a hybrid member of the genus Pelargonium, which is commonly known as the storksbills and forms part of the Geranium family. It’s a perennial bushy plant, also sometimes called a subshrub, with crinkled and serrated leaves.

Mosquito repellent… or not?

So, I’m sure you’ve heard of citronella plants repelling mosquitoes. This Pelargonium’s common name is “mosquito plant” for a reason, right?

In fact, that’s what it was marketed for right from its first introduction to the houseplant world. There’s a lot more to it, though! Strap in for a weird and wonderful ride, we’re diving down the rabbit hole.

You see, Pelargonium ‘Citrosum’ was bred specifically to be a new natural revolution in anti-mosquito products (or, as it was described in one 1992 Organic Gardening magazine article, a ‘skeeter skeedaddler’). 

In the 1980s, a Dutch plant breeder called Dirk van Leenen introduced his new citronella plant with much ado, particularly in Florida, knowing that mosquitoes are the bane of every Floridian’s existence. This is also why this plant is still sometimes called Pelargonium × citrosum ‘Van Leenii’. 

Van Leenen stated that his plant was a manmade hybrid created through tinkering with DNA by means of tissue culture, supposedly combining the African Pelargonium genus with lemongrass. 

While that’s quite clearly nonsense (we’re talking about something that supposedly happened in 1975, when this technology wasn’t really available), I still can’t find much about the actual “ingredients” that went into this plant.

Pelargonium ‘Citrosum’ vs. Cymbopogon sp.

I think much of the confusion about the Pelargonium ‘Citrosum’ plant being able to keep your home mosquito-free has a lot to do with it sharing a common name with—and smelling very similar to—plants that actually do repel those pesky flying bloodsuckers. Lemongrass!

Let’s not forget that Dirk van Leenen apparently claimed to have genetically spliced the two species in order to create his citronella geranium.

There are two species considered to be “true” citronella: Cymbopogon nardus and C. citratus. These plants are the actual sources of the widely used citronella essential oil, which you can buy in the form of sprays or citronella candles.

Caring for Pelargonium ‘Citrosum’

Light and temperature

Although most gardeners like to grow their citronella plant outdoors for the majority of the year, it can also do well as a houseplant. You just have to make sure to give it enough light! 

Indoors, a Pelargonium ‘Citrosum’ will appreciate being placed in a bright windowsill that gets at least some direct sun. If you don’t have any well-lit spots available, you can also opt to supplement with artificial grow lights. If your plant begins to stretch, it needs to be moved to a brighter location.

In terms of temperature, as long as long as things don’t dip below freezing, your citronella plant should technically be fine. Still, if you’re growing yours outdoors, it’s recommended to bring it in when temperatures begin to drop below 50°F. Warmer is not a problem, as Pelargoniums actually prefer tropical temps.

Want to grow a citronella outdoors year-round? You can do so if you’re in USDA Zone 9 or up.

Water and humidity

Finding the right balance in terms of moisture is an important part of keeping your citronella plant healthy. Although they do like plenty of water, these geraniums really don’t appreciate wet feet. 

Soil and planting

Although Pelargonium ‘Citrosum’ can thrive in a wide range of soil types, your best bet is to go for a mixture that’s both rich and well-draining. Try adding a handful of perlite and some worm castings to regular houseplant potting soil. Peat moss is also sometimes included, but you can substitute coco coir if you prefer.

Citronella plants are pretty vigorous growers, so you can go for a relatively large pot for yours without issue. The planter material and shape don’t really matter; the important thing is for it to have a drainage hole in the bottom to prevent excess water from causing root rot.

Fertilizing

Like most houseplants, the citronella plant appreciates a little boost from time to time during the growing season. As mentioned, after all, they grow pretty quickly!

You can use a balanced liquid houseplant fertilizer around once a month or so from spring to fall. Don’t fertilize in winter, as the plant probably won’t be growing and doesn’t need the extra nutrients. Also hold off on the fertilizer if it appears to be struggling, as that will only make things worse.

Pruning

Although pruning a citronella plant is a pretty pleasant experience thanks to the scent, they generally don’t need a lot of maintenance. Still, there are a few situations in which you may want to prune yours:

• You can deadhead flowers after they’re spent to encourage more blooms.
• It’s okay to prune any leaves that have stretched (etiolated) if you think they’re unsightly. Etiolation can happen in winter, when not as much light comes in, or if you need to move your plant closer to a window.
• Removing some taller stems can encourage a citronella plant to grow bushier.
• Any dead foliage can be removed once it has turned crispy.

Dividing or repotting

Most potted citronella plants consist of a single stem, as they don’t tend to produce many offshoots. This means that division is usually not an option. If yours is outgrowing its current planter, you’ll either have to aggressively prune it back or repot it into a bigger container.

I personally prefer the latter option! There’s nothing like a huge citronella to fill a space with wonderful lemon scent every time you brush past it, so I like to let mine grow as big as possible. 

You can repot a Pelargonium ‘Citrosum’ into fresh soil every other spring, optionally going up one pot size if your plant needs more space.