With its mini tree trunk-like stems and beautifully glossy leaves, the Australian Chestnut (Castanospermum Australe) makes a stunning addition to your home. The Australian Chestnut is actually part of the bean family (Fabaceae), but you could be forgiven for thinking that it looks like a miniature tree!
Also known as the Moreton Bay Chestnut, Blackbean or even Jack’s Beanstalk, this unusual-looking houseplant sprouts upwards from three or four chestnut-like seeds. A native plant of the East Coast of Australia, the Castanospermum Australe is prized for the shade that its dense foliage offers.
Traditionally, the seeds of the Australian Chestnut have also been a source of food in Australia for the Aboriginal people. However, the seeds are toxic unless prepared very carefully – we do not recommend trying them at home.
As an indoor houseplant, the Castanospermum Australe can be grown in controlled conditions to achieve your desired size and shape. The strong, speckled stems, topped with lush, green foliage tend to draw the eye upwards, adding a sense of height to your indoor space. The Australian Chestnut is a straightforward plant to care for – read on for some hints and tips to get the best out of your plant!
Watering Your Australian Chestnut
As a general rule of thumb, water your Australian Chestnut once a week. For best results, wait until the top of the soil has dried out and then give it a good drink. Reduce watering in the autumn and winter.
#BBX tip: Always remove your plant from the outer pot when you water it and do not return it to the ceramic pot until it's stopped dripping. This should save you from overwatering.
#BBX tip: Using lukewarm water should improve the overall health of your plant, as the Castonospermum Australe’s root system is quite sensitive to temperature change.
How Much Light Does My Australian Chestnut Need?
Your Australian Chestnut likes a light, sunny position. Just be wary that too much direct sunlight could lead to sun scorch or dehydration (yes, sometimes there can be too much of a good thing!). In the UK, you’re unlikely to experience a problem with too much sun, unless you position your Australian Chestnut in a real suntrap.
#BBXHint: Try popping your Australian Chestnut somewhere that has light almost immediately overhead, for even growth. A window sill or under a grow light should be ideal conditions.
How to Maintain Your Australian Chestnut
The great news is that the Castanospermum Australe is relatively low-maintenance! If it starts to get too gangly, you could prune away the offshoots, which will encourage it to grow out bushier. We suggest pruning your Australian Chestnut every 2 years or so – you’ll be rewarded with a fuller, healthier-looking plant.
While you’re at it, you’ll also need to repot your Australian Chestnut around every 2 years, in the spring. If it’s time for a new pot, be sure to check out our extensive range of pots and accessories.
#BBX tip: Make sure you give your plant a good drink around 24 hours before you repot it. This should help to reduce transplant shock. For more about repotting, check out Mama Botanica's video.
Fertilising your Australian Chestnut
The Australian Chestnut shouldn't need regular fertilising, particularly in the first year. After that, you may want to boost the nutrients in your houseplant’s soil with an all-purpose organic elixir, like this Organic Plant Food by Botanopia. Simply dilute one drop of the fertiliser with 250ml of water.
What’s the Best Temperature & Humidity for my Australian Chestnut?
Being a native of Australia, the Australian Chestnut tends to prefer warmer temperatures. It grows well in temperatures between 10-26°C. You could even take it outside in the summer, as long as the temperature remains above 12°C and you keep it in a sheltered location.
#BBX tip: If you decide to take your plant outside, remember to avoid direct sunlight as much as possible. Otherwise, your Castanospermum Australe will get a bit dehydrated.
In terms of humidity, regular UK room humidity will be absolutely fine for your Australian Chestnut. If you’re worried about the air being a little dry, you could use an electric humidifier or diffuser to boost the moisture in the air. But with soaring energy prices right now, you could go the old-fashioned route and make a humidity tray for your Australian Chestnut. Simply grab a saucer or tray and fill it with stones. Then fill your chosen vessel with water, and place your plant pot on top.
#BBX tip: Avoid placing your Australian Chestnut too close to a working radiator, as this may dry out your plant.
What’s the Best Soil for My Australian Chestnut?
The Castanospermum Australe likes well-draining, fertile soil. A potting soil for indoor plants, like Pokon’s Compact Soil, should be ideal. This high-quality soil stores nutrients, holds moisture in and protects roots – it does everything a good soil should do! Best of all, it’s 100% natural and comes pre-fertilised, giving your Australian Chestnut all the nutrients it needs for up to 2 months.
Frequently Asked Questions
Are My Pets Safe Around My Australian Chestnut?
You do need to choose the location of your Australian Chestnut carefully. The stems shoot up from the chestnut seeds, which remain on the surface of the soil. Whilst it gives the plant a truly unique look, the seeds are toxic and should not be eaten. Keeping your Australian Chestnut in a higher location may help to deter curious pets and small children. Always be mindful of your surroundings.
Will my Australian Chestnut grow Flowers?
In the wild, the Australian Chestnut grows to heights of around 40m. In addition to the dense, green foliage, the Castanspermum Australe will bloom with masses of beautiful yellow and red pea-shaped flowers during the spring. Sadly, the indoor conditions for an Australian Chestnut mean that it is unlikely to bloom.
Why are my Australian Chestnut’s Leaves Turning Grey & Yellow?
Some common problems experienced when caring for an Australian Chestnut are under- or over-watering.
Greying and yellowing leaves, withered leaves, yellow spots and stunted growth tend to point towards underwatering. Remember to water your plant regularly, whenever the top soil starts to become dry to the touch.
If only the lower leaves are yellowing, the stem starts to turn soft or the plant starts to rot in places, you’ve likely overwatered your Australian Chestnut. To remedy this, you can try relocating your plant to a sunnier spot or making sure that you have allowed the water to stop dripping from the drainage pot, before returning your plant to its ceramic home.
As Easy as 1-2-3!
Hopefully, you feel better equipped to dole out some TLC to your Australian Chestnut (Castanospermum Australe). With a little care, this perennial miniature tree should give you many, many years of enjoyment.
Did you know that the Australian Chestnut has been featured as the star plant in our Classic Subscription Box? By subscribing to our Bloombox Club Plant Subscription, you’ll receive a freshly hand-picked plant, just like the Australian Chestnut, every, single month! And if you received your Australian Chestnut in one of our previous subscription boxes, we’d love to see how your plant is doing now! Tag us on Instagram (@bloomboxclub)!