Backhousia citriodora aka Australian Lemon Myrtle

Backhousia citriodora is also known as lemon myrtle. It is part of the myrtle family. It comes from Queensland, in the north-east of Australia. There, it grows in forests near the coast and rainforests. This evergreen plant forms a tall shrub or small tree. Its growth is slow, with branches often near the ground. Garden plants seldom exceed about 15–16 feet [4.6–5 metres]. Wild trees may reach 66 feet [20 metres].

Crush the leaves, and they give off a strong lemon scent. Their oils give them both their scent and flavour. Small white flowers grow in groups and smell of lemon. Chicago Botanic Garden lists bloom times from March to June. The blooms draw birds and insects, which include butterflies. Its upright shape suits use as a specimen tree. Growers also raise it for its leaves and oil.

Lemon myrtle grows best in warm tropical and subtropical climates. It also grows in mild temperate sites with no frost. Give it full sun and rich soil that drains well. It likes moist soil and needs a moderate amount of water. Once plants take root and settle in, they withstand some drought. It grows in many soils, but poor drainage causes problems. Soil close to neutral suits it. Alkaline soil can make the leaves turn yellow. Shield it from strong winds and guard young plants against frost. Chicago Botanic Garden lists USDA zones 9–11. Some mature plants have survived brief cold spells near 18°F [−8°C]. This does not mean young plants can stand that cold.

Fresh or dried leaves, flowers, and seeds can flavour food. Leaves and stems with blooms also make tea with a lemon taste. Indigenous Australians have used the leaves as food and to heal. The plant now serves the bushfood trade in Australia. Its leaf oil goes into soaps, perfumes, and food flavourings. The plant has different chemical forms. Their oils are rich in citral or citronellal. Growers favour the citral-rich form for its lemon scent. Research cited by the sources reports effects that fight microbes and repel insects. Useful Tropical Plants lists no known hazards. This does not prove that the strong, concentrated oil is safe for every use.

Growers can raise new plants from seed or cuttings. Seeds can be hard to sprout, and cuttings take time to root. Low branches may touch the soil and form roots. Growers can split off these rooted branches to make new plants. The wood has a pale pink tone and fine grain. It is also hard and heavy.