The herb Cymbopogon citratus, commonly known as lemongrass, is a fragrant, tropical perennial prized for its culinary and aromatic qualities. This tall, clumping grass is a popular addition to many gardens, especially for those interested in Asian cooking or natural pest control. Companion planting involves growing different plants together for mutual benefit, maximizing the health and productivity of your lemongrass. Choosing the right neighbors can improve soil quality and manage pests naturally. Selecting companions involves understanding the specific needs of lemongrass and finding plants that share or complement those requirements.
Understanding Lemongrass Growing Requirements
Lemongrass is a sun-loving plant that needs substantial heat and light to flourish. It performs best in full sun, requiring a minimum of six hours of direct sunlight daily. Since it originates from tropical regions, the herb requires consistently warm temperatures and high moisture levels.
The soil environment is crucial for successful growth. Lemongrass thrives in rich, loamy soil that is well-drained but kept consistently moist. While it is not drought-tolerant, it will not tolerate waterlogged conditions, which can lead to root rot. The ideal soil pH is slightly acidic to neutral, generally falling between 6.0 and 7.0. Companion plants must tolerate these same high-sun and high-water conditions.
Companions for Pest Management and Protection
The strong, citrusy scent of lemongrass, derived from the compound citronella, acts as a natural insect repellent for many common pests like mosquitoes. However, smaller insects, such as aphids, whiteflies, and spider mites, can still target the plant. Companion planting provides a secondary layer of defense against these garden nuisances.
Aromatic herbs and flowers work by masking the lemongrass scent or actively repelling pests. Basil is an excellent choice, as its pungent aroma deters whiteflies. Marigolds repel nematodes in the soil and aphids above ground, acting as a powerful living border. Nasturtium functions as a sacrificial trap crop, attracting aphids away from the lemongrass foliage. Planting these companions nearby creates a protective aromatic barrier, reducing the need for chemical intervention.
Plants That Thrive Alongside Lemongrass
Successful neighbors share the demanding tropical growing conditions of lemongrass, particularly the need for abundant moisture and sun. Nightshade vegetables, such as tomatoes and sweet peppers, are good partners because they also prefer consistent watering and high heat. These vegetables benefit from the pest-deterrent qualities of lemongrass, and their similar requirements simplify irrigation.
Other tropical root crops, like ginger and turmeric, are well-suited as they appreciate rich, moist soil and warm conditions. Cilantro is another herb that pairs well, sharing identical light and water needs and attracting beneficial insects like parasitic wasps.
Low-growing herbs such as thyme or oregano can serve as a living mulch, helping to suppress weeds and conserve soil moisture. Nitrogen-fixing legumes, such as bush beans, enrich the soil by converting atmospheric nitrogen into a usable form, supporting the heavy feeding needs of lemongrass.
Plants to Never Plant Near Lemongrass
Some plants should be kept away from lemongrass due to differing environmental needs or competitive growth habits. Plants that prefer dry soil, such as rosemary and sage, struggle near lemongrass, which requires consistently moist ground. The high moisture needed by lemongrass can lead to root issues or disease in these drought-tolerant herbs.
Any plant with an aggressive root system can severely compete with lemongrass for water and nutrients. Fennel is particularly problematic because it exhibits allelopathy, releasing chemicals that inhibit the growth of many neighboring plants. Large, heavy-feeding vegetables, including brassicas like cabbage or broccoli, should be avoided. Their high demand for soil nutrients will directly compete with the lemongrass, leading to stunted growth and poor health.