Castanospermum australe (common name: ‘lucky bean plant’, ‘Moreton Bay chestnut’ or ‘black bean’) is known by savvy gardeners and florists as a striking and easy to grow houseplant.
It’s also one of the easiest plants to propagate from seed, ever.
In the wild, Castanospermum australe grows in coastal rainforests on the east coast of Australia. It can grow to 40 meters when mature!
You wouldn’t think a 40 m tree would thrive in a pot, indoors, would you?
In fact, Castanospermum australe makes a great houseplant that will grow happily for years in a pot. Its size will be limited by the size of the container used (and whether or not you water it and provide its basic needs to survive…).
You can buy Castanospermum australe from community native plant nurseries and some commercial nurseries/florists/garden shops. But, if it is grown as a street tree or garden specimen in your area (or even in the wild) you can collect the seed and propagate it yourself!
You won’t regret it because a. it’s easy and the results are beautiful and b. it’s free.
Collect and propagate
1. Find a tree that has seeds. March to May is the time to find Castanospermum australe seeds, they are present in large cylindrical pods filled with 3 – 5 chestnut shaped seeds.
2. Collect the seed pods or seeds that have fallen out of the pods and are lying on the ground. I suggest taking more than 10 seeds if they are available (if a tree is seeding there are generally heaps) as some may not germinate, and you may want to plant several in a pot together. Store the seeds in a cool dry place (like a cupboard or garage).
3. To germinate the seeds need temperatures of approximately 18 – 25 degrees so don’t try if it is much colder than that, or don’t put them in a very hot spot that will result in temperatures greater than 25 degrees.
4. Choose a propagation medium One guide I read suggested using a mix of 50% sand and 50% perlite (read here) as the planting medium . This works well, however for the lazy gardener you can also plant straight into regular store bought potting mix.
5. Choose a pot Find a small pot, anywhere from 5 – 10 cm in diameter and fill with your chosen propagating mix. I like to plant several seeds in the same pot (so depending on how many seeds you have you will need to very your pot size accordingly). This means that several stalks will grow at once and will result in a more lush and full houseplant immediately.
- Plant the seed with the nib facing down and the lobed bit of the seed up ( the bit that kind of looks like bum cheeks). This is important as the growing seedling will crack the seed open to emerge and needs the lobed bit (bum bit) facing up to be able to do this. This should take a few weeks depending on temperature.
Growing tips
- Castanospermum australe likes dappled shade to partial sun. For example, a few hours of light morning sun or late afternoon winter sun. Not 5+ hours of summer western or northern sun.
- Allow to dry out between waterings (put your finger in the soil in the pot to check moisture levels, if damp leave, if dry water). Generally, you will need to water more in summer (3-5 times per week depending on temp) than winter (approximately once per week) and depending on whether your plant gets direct or dappled sun.
- Apply liquid or granular fertiliser approximately 6 months – 1 year after potting.
Happy gardening!
NativeBotanics 