Citronella Grass

Name: citronella, (Cymbopogon nadus, C. winterianus).

Height: clump-forming grass to 1–2m tall and 1m wide.

Foliage: mid-green grass blades, reddish at the base.

Climate: sub-tropical to temperate; grow in pots indoors in cooler areas.

Soil: rich loam soil that retains some moisture but drains well after rain or watering.

Position: can tolerate full sun but prefers light shade with good ambient light for 6–8 hours daily.

Flowering: typical grass flower stems and seed heads; not relevant to culture.

Feeding: needs continuous supply of nutrients via controlled-release and liquid fertilisers.

Watering: consistently moist but not wet soil; do not let roots dry out.

Appearance and characteristics of citronella

Citronella is a tall grass native to South-East Asia, and has typical grass form and habit. Although its primary purpose is for production of citronella oil, it is also cultivated as an ornamental grass for the garden or for pots. There are two species of citronella grass, but Cymbopogon nardus is more commonly grown for its oil.

Citronella’s mid-green leaf blades grow from a crown and can be up to 1m long. The base of the leaf, known as a pseudostem, is a reddish colour. Like all grasses, it does produce flower stems and seed heads, but they are not the main attraction.

Citronella looks like, and is closely related to, lemongrass, but they are not interchangeable! Lemongrass does not have any red at the base of its stems—they are green.

Uses for citronella

Citronella is grown as a commercial crop in India, Sri Lanka, Burma and Indonesia. It contains essential oils that are extracted for use in insect repellents, soaps, candles and other aromatherapy and cosmetic products. It is also used to treat lice and other parasites (including intestinal worms!).

Citronella is used as a spice in Indonesia and has many uses in herbal medicine. It is claimed to have anti-inflammatory, anti-microbial and anti-bacterial properties. It’s also used as an anti-fungal in cleaning products.

The plant itself doesn’t repel insects, but crush its leaves and rub them on your clothing, and the mosquitoes will stay away. It has a mild lemon/citronella scent, and is sometimes grown as a companion plant in the vegie garden to deter white fly and other troublesome insects.

How to plant and grow citronella

Climate

Citronella grows well outdoors in most climates, but doesn’t like cold. In cooler regions, it does best on a sheltered verandah, and will even do well indoors. In the garden, choose a lightly shaded spot that gets good light for most of the day. Citronella will scorch and wilt in full sun, especially in summer.

Soil

The soil should be a rich loam that holds moisture after watering and rainfall but also drains freely—grasses don’t like waterlogged soils. Before planting, add plenty of well-weathered animal manure and compost as well as a long-term controlled-release fertiliser (12 month formulation is ideal).

Growing citronella in pots

When growing in a pot, choose a pot size that comfortably holds the roots, with room for some expansion over the next couple of years.  A premium-quality terracotta and tub potting mix that includes a wetting agent and water-storing crystals is best.

Caring for citronella

Citronella needs plenty of moisture to grow well, but it also dislikes wet feet. Over summer when it’s hot and dry, water plants in the garden and in pots every day. When the weather cools, check the soil or potting mix every few days and water if it feels or looks dry.

Apply a 12-month controlled-release fertiliser at the start of spring each year, and supplement that with monthly applications of a water-soluble or liquid plant food to keep the grass strong and healthy.

Pruning and dividing citronella plants

Although citronella is a perennial, in cooler areas where it is grown as an ornamental garden plant, it can be treated as an annual. Pull it out and add it to the compost at the end of autumn after its seed heads have died off.

Plants that will remain in the ground or pots can be given a “haircut” in late autumn, trimming the grass down to about 15cm or so above soil level. It will produce plenty of new growth in spring to cover the stubble.

When clumps become congested, lift, divide them up and replant in autumn.

Citronella is a grass that spreads both by expansion of its clump and also by seed, so it does have potential to become a pest plant. It doesn’t have running roots, but its seeds can be carried by the wind onto neighbouring properties. Prevent spread by cutting off seed heads before they mature, and don’t allow your unwanted divisions of clumps to become “garden escapees” by dumping them on roadsides or vacant land!

Diseases and pests

Citronella isn’t prone to any specific pests or diseases that need treatment.

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