Lemon myrtle Backhousia citriodora
Lemon myrtle (Backhousia citriodora) is an evergreen perennial shrub in the Myrtaceae family, native to Subtropical rainforest of Queensland, Australia. It grows 3–8 m (10–26 ft) tall and 2–4 m (6.6–13 ft) wide, wants full sun and moderate water, and is hardy to about -3 °C (27 °F). Space plants about 2.5 m (8.2 ft) apart.
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Lemon myrtle at a glance
| Type | Perennial shrub, evergreen |
|---|---|
| Family | Myrtaceae |
| Mature height | 3–8 m (10–26 ft) |
| Mature spread | 2–4 m (6.6–13 ft) |
| Spacing | 2.5 m (8.2 ft) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance low |
| Soil pH | 5.5–7 |
| Cold hardiness | About -3 °C (27 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 38 °C (100 °F) |
| Flowering | from about July for 6–13 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Moderate |
| Pollinator value | High |
| Edible | Yes: leaves |
| Native to | Subtropical rainforest of Queensland, Australia |
| Common in gardens of | 🇦🇺 Australia |
Is Lemon myrtle toxic?
- People: mildly toxic
- Cats: not well documented
- Dogs: not well documented
- Parts: essential oil
Citral-rich oil can irritate skin and mucous membranes in concentrated form; leaves are used in small amounts for flavour.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Lemon myrtle
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Keep apart or take care
- caution With Guava: Myrtle rust (Austropuccinia psidii) infects guava, feijoa, Surinam cherry and many other Myrtaceae; it spreads by airborne spores between them. Evidence B
Questions about Lemon myrtle
- How far apart should I plant Lemon myrtle?
- About 2.5 m (8.2 ft) apart, centre to centre. A mature plant spreads 2–4 m (6.6–13 ft).
- Does Lemon myrtle need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Lemon myrtle need?
- Moderate water. Drought tolerance is low and waterlogging tolerance low.
- How cold-hardy is Lemon myrtle?
- It tolerates about -3 °C (27 °F) once established, roughly USDA zone 9.
- When does Lemon myrtle flower?
- From about July for 6–13 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Lemon myrtle poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people mildly toxic. Citral-rich oil can irritate skin and mucous membranes in concentrated form; leaves are used in small amounts for flavour.
- What grows well with Lemon myrtle?
- There is no well-documented companion pairing for Lemon myrtle. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Australian native plant profiles, Australian National Botanic Gardens / Australian Plants Society
- RHS Plant Finder, Royal Horticultural Society
- Plants For A Future database, PFAF
Notes and assumptions
- Susceptible to myrtle rust (Austropuccinia psidii) in Australia. Mature plants tolerate light frosts; young plants need protection. Usually pruned to 2-4 m as a hedge or for leaf harvest.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Guava Psidium guajava
- Feijoa Acca sellowiana
- Surinam cherry (pitanga) Eugenia uniflora
- Cider gum (eucalyptus) Eucalyptus gunnii
- Lilly pilly Syzygium smithii
- Crimson bottlebrush Melaleuca citrina
- Mānuka (tea tree) Leptospermum scoparium
- Pōhutukawa (NZ Christmas tree) Metrosideros excelsa