Can you grow Xanthorrhoea johnsonii as a house plant?

Xanthorrhoea johnsonii, commonly known as Johnson's grass tree
Xanthorrhoea johnsonii by Mark Marathon is licensed under CC BY-SA 4.0

Xanthorrhoea johnsonii, commonly known as Johnson’s grass tree, is an iconic Australian plant with a unique appearance and fascinating history.

While traditionally found in the wild, this article explores the possibility of growing this remarkable plant indoors and provides guidance on how to do so successfully.

So, can you grow Xanthorrhoea johnsonii as a house plant?

In summary, it is rare to grow it as a house plant but it can be done. I have done so but only keeping it indoors in the UK in winter to protect it from cold. In that case, I kept it in a cool conservatory in the winter months and placed it outside again in Spring.

But note, I only had the plant for about 3 years before, ironically, I moved to Australia I had to give the plant away and I am not sure what happened to it after that.

Origins and indigenous uses

Xanthorrhoea johnsonii is such a beautiful and fascinating plant. It is native to eastern Australia, primarily found in Queensland and New South Wales. The plant has deep cultural significance for Indigenous Australian peoples, who have utilised various parts of the grass tree for thousands of years.

Indigenous uses include:

  • Resin: Used as an adhesive for tool-making and as a fire starter
  • Flower spikes: Employed to make spear shafts
  • Leaves: Woven into baskets and used for thatching
  • Nectar: Consumed as a sweet treat or fermented into an alcoholic beverage

Natural habitat and outdoor growing conditions

Xanthorrhoea johnsonii inflorescence
Danaus plexippus Monarch on Xanthorrhoea johnsonii inflorescence 74 Sunbury St Geebung P1100183” by John Robert McPherson is licensed under CC BY-SA 4.0

In its natural habitat, Xanthorrhoea johnsonii thrives in the following conditions:

  • Climate: Subtropical to temperate
  • Soil: Well-draining, sandy or rocky soils
  • Sunlight: Full sun to partial shade
  • Water: Drought-tolerant once established
  • Temperature: Tolerates light frosts but prefers warmer climates

Likelihood of success and challenges

While it is theoretically possible to grow Xanthorrhoea johnsonii as a houseplant, it is important to understand that the likelihood of long-term success is relatively low. This is primarily due to the plant’s specific environmental requirements and growth characteristics, which are challenging to replicate in an indoor setting.

Challenges of indoor cultivation

  1. Slow growth rate: Xanthorrhoea johnsonii is notoriously slow-growing, often taking decades to reach maturity. This makes it difficult to observe progress and can be discouraging for indoor gardeners.
  2. Light requirements: Providing sufficient light indoors can be challenging. Even bright indoor spaces may not match the intensity of its natural sunlight exposure.
  3. Dormancy needs: In its natural habitat, the plant experiences seasonal changes and periods of dormancy, which are difficult to replicate indoors.
  4. Specialised soil needs: Recreating the well-draining, nutrient-poor soil conditions it prefers can be tricky in a pot.
  5. Watering balance: Achieving the right balance between drought tolerance and adequate hydration is challenging in an indoor environment. It is really easy to over-water this plant
  6. Humidity and air circulation: Indoor air can be drier and more stagnant than the plant’s natural environment, potentially leading to health issues.
  7. Temperature fluctuations: Protecting the plant from sudden temperature changes, especially near windows or air conditioning units, can be difficult.
  8. Lack of symbiotic relationships: In nature, Xanthorrhoea johnsonii benefits from symbiotic relationships with soil microorganisms, which are absent in potting mixes.

Success rate and expectations

Given these challenges, the success rate for growing Xanthorrhoea johnsonii as a long-term houseplant is relatively low. However, with meticulous care and the right conditions, it is possible to maintain the plant indoors for several years, albeit with slower growth than in its natural habitat.

Gardeners considering this plant should set realistic expectations:

  • Expect extremely slow growth, with little visible change over months or even years.
  • Be prepared for potential setbacks and the need to adjust care routines frequently.
  • Consider starting with a smaller, younger plant that may adapt more easily to indoor conditions.
  • View the experience as an experimental and educational endeavour rather than a guaranteed success.

Replicating natural conditions indoors

Xanthorrhoea johnsonii, commonly known as Johnson's grass tree - natural habitat
“Xanthorrhoea johnsonii in open forest Pine Ridge Conservation Park, Queensland by John Robert McPherson is licensed under CC BY-SA 4.0

Despite the challenges, if you’re determined to grow Xanthorrhoea johnsonii as a houseplant, here’s how to replicate its natural conditions:

Lighting

Provide bright, indirect light for at least 6 hours daily. Place the plant near a south-facing window with sheer curtains to filter intense sunlight. Supplement with grow lights if necessary.

Soil and potting

Use a well-draining potting mix formulated for succulents or cacti. Add coarse sand or perlite to improve drainage. Choose a pot with ample drainage holes and consider using a terracotta pot to help regulate moisture levels.

I added some mycorrizhal fungi to the potting mix when I grew the plant. To be honest, it is hard to know if that made any difference bearing in mind these were not specific to this plant and the types of fungi that would occur in its natural habitat.

Temperature and humidity

Maintain temperatures between 15-30°C (59-86°F). Protect the plant from cold drafts and sudden temperature fluctuations. While Xanthorrhoea johnsonii tolerates average indoor humidity, it may benefit from occasional misting or placement near a humidity tray.

Watering

Water sparingly, allowing the soil to dry out completely between waterings. Reduce watering frequency during winter months. Overwatering can lead to root rot, which is particularly detrimental to this slow-growing plant.

Care and maintenance

Fertilising

Feed sparingly with a balanced, low-strength fertiliser during the growing season (spring and summer). Avoid over-fertilising, as Xanthorrhoea johnsonii is adapted to nutrient-poor soils.

Pruning

Minimal pruning is required. Remove dead or yellowing leaves at the base of the plant as needed. Be cautious when handling the plant, as the leaves can be sharp.

Repotting

Due to its slow growth rate, repotting is infrequent. When necessary, repot in spring, using a container only slightly larger than the current one.

Pest and disease management

Monitor for common houseplant pests such as spider mites and mealybugs. Treat infestations promptly with insecticidal soap or neem oil. Ensure good air circulation to prevent fungal issues.

Conclusion

Growing Xanthorrhoea johnsonii as a houseplant presents significant challenges and has a relatively low likelihood of long-term success. However, for dedicated plant enthusiasts willing to invest time and effort into its care, it can be a rewarding and educational experience.

Success in growing Xanthorrhoea johnsonii indoors requires patience, careful attention to its specific needs, and a willingness to adapt care routines. While the growth rate will be extremely slow, those who manage to maintain this plant will have a distinctive and conversation-starting addition to their indoor garden.

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