Citronella, the mosquito-repellent plant: what to really expect (and how to grow it)

Imagine a warm summer evening, the sky turning orange and purple as you enjoy a moment of relaxation on your balcony or in your garden. Everything would be perfect were it not for that annoying buzz announcing the arrival of mosquitoes. It is at times like these that many of us turn to citronella (Cymbopogon nardus), a plant with an unmistakable fragrance, hoping for some relief. But what can we really expect from this green ally? Our experience in botany has taught us that citronella is a valuable contribution to the serenity of summer evenings, provided you understand its limitations and potential. It is not a miracle solution, but with the right care and placement, it can transform your outdoor space into a more welcoming oasis. In the outdoor plants collection, you will find our current selection.

If you are looking for balcony plants with similar requirements, discover our outdoor flowering plants.

Citronella: an ally, not a miracle

When we talk about citronella as a "mosquito-repellent plant," it is essential to approach the subject realistically. The most common question is: does it really work? Based on years of observation and cultivation, our answer is yes, but with important qualifications. True citronella, scientifically known as Cymbopogon nardus or Cymbopogon winterianus, is a tropical grass that releases volatile essential oils. These oils, notably citronellal, geraniol, and citronellol, are known for their ability to mask the odors that attract mosquitoes, interfering with their olfactory system. They do not kill insects or create an impenetrable barrier; rather, they disorient them and make them less likely to approach.

The effectiveness of a single potted lemongrass plant is inherently limited. Essential oils are released into the air in relatively small quantities and tend to disperse quickly, especially in open, ventilated spaces. We have found that its repellent effect is noticeable within a radius of approximately 50-100 centimetres of the plant itself. This makes it an excellent solution for protecting a small, specific area, such as a coffee table on a balcony or a reading nook, but not for "clearing" an entire garden. It is important to distinguish true citronella grass (Cymbopogon) from other plants often labelled as "citronella", such as Pelargonium citrosum, commonly called "mosquito-repellent geranium". Although the latter produces a similar scent, the concentration and composition of its essential oils are different, and its effectiveness as a repellent is generally considered lower than that of authentic Cymbopogon. Our experience leads us to always recommend the true grass to obtain the desired benefits.

To maximize the effect of lemongrass, it is helpful to understand that it works best as part of a broader mosquito-control strategy. It cannot replace eliminating standing water, using mosquito nets, or other methods, but it can complement them perfectly, providing an additional layer of natural protection. Its fresh, citrusy scent is a bonus, making the environment more pleasant for us as well. In short, lemongrass is a valuable aid in the fight against mosquitoes, offering targeted and pleasant protection, but it is essential to manage expectations and position it strategically to fully appreciate its benefits.

Choosing and positioning your lemongrass

Choose lemongrass with bright green, firm leaves free of spots, healthy white roots, and no signs of pests. Place it where it receives at least 6 hours of direct sunlight a day, near the areas where you spend the most time, such as tables and lounge chairs, in a sunny spot that is slightly sheltered from the wind.

Choosing a healthy plant is the first step to ensuring vigorous, fragrant citronella. When selecting your plant, look for specimens with bright green leaves, without spots or yellowing. The leaves should look turgid and not wilted. Also check the base of the plant to make sure there are no signs of pests or disease. A good root system is essential: if possible, inspect the bottom of the pot to see whether the roots are white and healthy, without being excessively tangled or protruding too much, which could indicate that the plant is root-bound and needs immediate transplanting.

Once you have chosen your citronella, positioning is crucial for its health and for maximizing its mosquito-repellent effect. As a tropical plant, citronella loves the sun. For optimal growth and abundant essential oil production, it needs at least 6 hours of direct sunlight per day. Insufficient exposure can lead to stunted growth and lower scent emission, reducing its repellent effectiveness. Place your plant where it can benefit from the morning and afternoon sun, such as a south- or southwest-facing balcony or a sunny corner of your garden.

As for its mosquito-repellent effect, the best strategy is to place citronella strategically in the areas where you spend the most time. We have found that the most effective spots are near outdoor dining tables, next to lounge chairs or small sofas, or at the entrances to doors and windows that remain open. To amplify the effect, consider grouping several plants together. For example, two or three "Citronella D.14 H.30 cm" pots placed around a seating area can create a broader, more concentrated protection zone. This not only increases the amount of essential oils released, but also creates a visually pleasing focal point. Remember that ventilation is an important factor: in an area that is too windy, the scent will disperse more quickly, reducing its effectiveness. If possible, choose a sunny but slightly sheltered spot to optimize the diffusion of the aromas.

Caring for citronella in a pot: step by step

To care for citronella in a pot, you need a container at least 20-30 cm in diameter with drainage holes, universal potting soil lightened with perlite or sand, consistent watering without waterlogging, even every 1-2 days in midsummer, a balanced liquid fertilizer every 2-4 weeks from spring to late summer, and repotting every 1-2 years.

Growing lemongrass in a pot is a rewarding experience, but it requires attention to a few simple steps to ensure the plant has a long and productive life. Choosing the pot is an essential starting point: lemongrass tends to grow quite large, so a suitably sized pot with a diameter of at least 20-30 cm is recommended to allow the roots to develop. Make sure the pot has drainage holes in the bottom to prevent waterlogging, which is this plant's number one enemy.

The ideal substrate for lemongrass is fertile, well-draining potting soil. A mix of good-quality universal potting soil with the addition of perlite or coarse sand in a ratio of approximately 3:1 (potting soil:perlite/sand) can ensure optimal drainage. Lemongrass prefers slightly acidic or neutral soil. As for watering, the golden rule is consistency without excess. During the warmer months, especially if the plant is exposed to full sun, it may be necessary to water it every 1-2 days. It is essential to check the soil moisture: insert a finger a couple of centimeters into the substrate; if it feels dry, it is time to water. Avoid leaving the saucer full of water for more than 20-30 minutes, as stagnant water can cause root rot that may be fatal to the plant. In winter, watering should be drastically reduced, keeping the soil just moist.

Fertilizing is another important aspect of supporting vigorous lemongrass growth. During the active growing season, from spring to late summer, we recommend applying a balanced liquid fertilizer for green plants every 2-4 weeks. Always follow the manufacturer's dosage instructions to avoid over-fertilizing, which could damage the plant. Pruning is not strictly necessary for the plant's health, but it can be useful for maintaining a compact shape and stimulating new growth. You can remove dry or damaged leaves at any time. If you want a fuller appearance, you can pinch back the stem tips in spring. Finally, repotting should be done every 1-2 years, or when you notice the roots beginning to emerge from the drainage holes, choosing a slightly larger pot to give the plant room to spread.

Lemongrass and winter: how to protect it

To protect citronella in winter, bring it indoors before the first frosts, placing it in a bright, sheltered environment where the temperature always remains above 10°C, drastically reduce watering, and stop fertilizing. Outdoor protection with mulch and non-woven fabric is riskier and should only be attempted where freezing does not occur.

Citronella is a tropical plant, which means it does not tolerate the cold. Its survival is closely tied to temperature: it cannot tolerate temperatures below 10°C, and frost is fatal to it. This is crucial for those growing it in temperate climates, where winter temperatures fall well below this threshold. Preparation for winter should begin well before the first frosts arrive, usually between late September and October, depending on the geographical area.

The first step is to bring the plant indoors. If your citronella is potted, such as "Citronella D.14 H.30 cm", you will need to move it to a protected environment. Ideally, this should be a bright but not too warm place, such as a cold greenhouse, a stairwell, a garage with windows, or a well-lit storage room. The important thing is that the temperature remains consistently above 10°C. During this sheltered period, the plant will enter a state of vegetative dormancy. Watering should be drastically reduced: the soil should be kept barely moist, watering only when the first few centimeters of substrate are completely dry. Absolutely avoid fertilizing during this period, as the plant will not need it and there is a risk of burning the roots.

If you do not have a suitable indoor space available and temperatures in your area do not drop excessively (never below freezing), you could try protecting the plant outdoors. This is a riskier method and is generally not recommended for citronella. However, if you have no alternatives, you can try heavily mulching the base of the plant with straw, dry leaves, or bark, and covering the entire plant with a non-woven fabric cover. This provides some degree of thermal insulation, but it is not a guarantee against frost. Our recommendation is always to opt for bringing the plant indoors to ensure its survival. With the arrival of spring and temperatures rising above 15°C, you can gradually move your citronella back outdoors, progressively acclimatizing it to direct sunlight to prevent sunburn. If carried out correctly, this winter protection process will allow you to enjoy your citronella plant for many years.

Integrated strategies for a mosquito-free environment

To have an environment with fewer mosquitoes, citronella should be combined with other measures: eliminate standing water in saucers, buckets, and gutters, keep the lawn mowed and hedges trimmed, use mosquito screens and fans, and, on evenings outdoors, use good-quality citronella candles or torches, together with other aromatic plants such as mint, basil, and lavender.

Relying exclusively on citronella to keep mosquitoes away would be a mistake. As we have seen, its effectiveness is localized and complementary. To create an outdoor environment that is truly more livable and less prone to mosquito invasions, it is essential to adopt an integrated strategy that combines different approaches. This means acting on multiple fronts, from prevention to active protection, to minimize the presence of mosquitoes in your space.

The first and most important step is prevention, which means eliminating standing water. Mosquitoes lay their eggs in stagnant water, even in very small amounts. Regularly check saucers, buckets, watering cans, gutters, or any container that could collect rainwater. Empty or cover them. If you have fountains or ponds, consider introducing fish that feed on mosquito larvae, such as mosquitofish. This simple measure can drastically reduce the mosquito population in your area. It is also useful to keep the lawn mowed and hedges trimmed, as mosquitoes like to shelter in tall grass and dense vegetation during the hottest hours of the day.

In addition to citronella, there are other plants that can help deter mosquitoes, although their effectiveness varies. Mint, basil, rosemary, lavender, and calendula are often mentioned for their repellent properties. Planting them strategically around seating areas can add an extra layer of aromatic protection. For more robust protection, especially in areas with high mosquito pressure, consider physical solutions such as mosquito screens for doors and windows, or using fans: the constant airflow makes it difficult for mosquitoes to fly and land. Finally, for evenings outdoors, citronella candles or torches (making sure they are good quality and have a high concentration of essential oil) can enhance the effect of the live plant by releasing more scent into the air. The goal is to create an environment that is less attractive to mosquitoes, combining the beauty and natural scent of citronella with common-sense practices and, if necessary, other protective tools.

Not just a mosquito repellent: additional uses of citronella

In addition to repelling mosquitoes, citronella is used as a natural air freshener for rooms, closets, and drawers, in cooking to flavor tea, herbal infusions, soups, and curries, especially when using the lemongrass species, and in the form of essential oil in soaps, lotions, candles, and perfumes, always well diluted and used with caution.

Beyond its reputation as a mosquito repellent, citronella is a versatile plant that offers several other uses, enriching our daily lives with its fresh scent and properties. It is important to emphasize that, when considering the internal or cosmetic use of citronella, this mainly refers to the essential oil extracted from the plant, which is highly concentrated. Direct use of the plant's leaves for purposes other than simply scenting indoor spaces requires caution and knowledge.

One of the simplest and most immediate uses is as a natural air freshener. Fresh citronella leaves, lightly rubbed or simply left in a vase, release a citrusy and refreshing aroma that can help neutralize unpleasant odors and create a livelier atmosphere at home. You can also tie some stems together and hang them in closets or drawers to scent your linens, or add them to homemade potpourri. The scent of citronella is also known for its invigorating and stimulating properties, which can help improve your mood and promote concentration.

In some cultures, citronella is also used in cooking, although it is less common than other aromatic herbs. The leaves and stems can be used to flavor tea, herbal infusions, or broths, adding a citrusy and slightly spicy note. It is particularly popular in Asian cuisine, where it is used to season soups, curries, and fish or chicken dishes. However, it is essential to make sure you are using the correct species of Cymbopogon (often Cymbopogon citratus, or lemongrass, is more common in cooking) and to consume it in moderation. Although citronella is generally considered safe, ingesting large quantities or using unsuitable species could cause adverse effects. Therefore, if you intend to use it in cooking, it is always advisable to get well informed and, if in doubt, consult an expert.

Finally, citronella essential oil is widely used in the cosmetics and perfumery industries to create soaps, lotions, candles, and commercial insect repellents. Its antiseptic and antibacterial properties also make it an interesting ingredient in skincare products, although it must always be properly diluted. The plant itself, with its beauty and fragrance, is an aesthetic and functional addition to any green space, offering much more than simple mosquito protection.

Frequently Asked Questions

Does citronella really keep mosquitoes away?

Potted citronella releases essential oils such as geraniol and citronellal, which disrupt mosquitoes' olfactory receptors. Its effectiveness is real but limited to a radius of about 50-100 cm from the plant, and it does not create a complete barrier. It is a useful aid for reducing nuisance in specific areas, but it should be considered part of a broader strategy.

Where should citronella be placed on a balcony for the best effect?

To maximize its mosquito-repellent effect and the plant's growth, place citronella in an area that receives at least 6 hours of full, direct sunlight per day. Ideally, place it near areas where you sit or spend time, such as tables or lounge chairs. Grouping two or three pots together can amplify the fragrance and repellent action.

How often should potted citronella be watered?

During the warm, sunny months, potted citronella requires frequent watering, even every 1-2 days. It is essential to keep the soil consistently moist but never waterlogged. Always check that the first few centimeters of substrate are dry before watering again, and empty the saucer within 20 minutes to prevent waterlogging.

How can citronella be protected during the winter?

Citronella does not tolerate temperatures below 10°C or frost. To protect it, it is essential to bring the plant indoors to a bright, cool environment, such as a cold greenhouse or stairwell, as soon as outdoor temperatures drop. During winter storage, drastically reduce watering and stop fertilizing completely.

Can citronella be used in cooking or for herbal teas?

Citronella leaves (Cymbopogon nardus/winterianus) are primarily used for their fragrance and as a repellent. Although the essential oil is used in various products, the direct use of the leaves in cooking or herbal teas is less common than lemongrass (Cymbopogon citratus). It is advisable to proceed with caution and learn about the specific species and its properties before ingestion.