Originally native to the coastal regions of New South Wales and Queensland, the plant can be planted both indoors and outdoors in our latitudes. Cultivated as a houseplant, the plant rarely forms flowers, contrary to the outdoor varieties; however, it still looks very decorative.

Location and soil

When purchasing an Australian chestnut tree, the first question to be answered is whether the plant should be grown outdoors or indoors.

When cultivating in the house, special conditions must be taken into account so that the plant can on the one hand develop optimally, but on the other hand does not become too big. The Australian chestnut prefers a generally bright location inside the house; however, the plant should be protected from blazing sun and direct sunlight. This applies in particular to young plants that are still growing and specimens that should first be accustomed to a new location. The blazing midday sun, which must be avoided at all costs, is particularly dangerous in this context. The ideal location is a partially shaded area on the window sill, which at the same time ensures that the temperature is as warm as possible. In addition, the selected location should not be directly next to a door, as strong drafts are poorly tolerated by the Australian chestnut. For this reason, care should be taken when ventilating the plants when the plants are on the windowsill. In this context, young plants are particularly sensitive. Once the location in the house has been chosen, it can be used all year round for cultivating the plant under optimal conditions; However, you should always make sure that the temperatures are never less than 12 ° C. In this context, young plants are particularly sensitive. Once the location in the house has been chosen, it can be used all year round for cultivating the plant under optimal conditions; However, you should always make sure that the temperatures are never less than 12 ° C. In this context, young plants are particularly sensitive. Once the location in the house has been chosen, it can be used all year round for cultivating the plant under optimal conditions; However, you should always make sure that the temperatures are never less than 12 ° C.

As a houseplant, with good care, the plant can reach a total size of 1.80m. However, specialists for bonsai plants are now also dealing with the breeding of small trees, so that adequate indoor plants will probably also be available in the future.

If the Castanospermum australe is to be put outdoors in summer, spacious areas are ideal, as the plant likes to develop freely. Locations that offer full or partial sun conditions are ideal; However, the Australian chestnut also tolerates areas in the garden that are in partial shade. During the summer months, the plant can be cultivated on the balcony as well as in the garden; However, it is then necessary to gradually get used to the sun, which is no longer filtered and only penetrates through the window. As a rule, the temperatures should not exceed 10 ° C, although 0 ° C may also prevail for a short time.

Note: Since the Australian chestnut has not been cultivated in our latitudes for a long time, suitable plant communities have not yet been determined.

With regard to the optimal soil, the following recommendations are given:

  • humic properties
  • permeable
  • fresh to moist
  • rich in nutrients
  • Substrate example: bucket earth, loosened with pumice gravel or sand

Particularly during the summer months, it must always be ensured that the soil has sufficient moisture; the tree must not dry out. So that indoor plants can also thrive optimally, the plant should be planted in a loamy soil that is equipped with a good drainage system. In this way, in particular, the formation of backwater is effectively avoided.

Watering, fertilizing, overwintering – care instructions

In order to enable the Australian chestnut to grow optimally outdoors, sufficient irrigation is of particular importance. The plant needs regular watering all year round, especially during the summer months and with persistent drought. However, waterlogging must be avoided at all costs. The plant must dry well between the individual waterings, but must not dry out. Regular watering is particularly important during the growth phase.

Indoor plants also need regular water supplies. After soaking, excess water should be removed from the planter to avoid waterlogging. In order to achieve optimal watering behavior, the young plant can also be soaked in a bucket with water. Before you put the plant back into the planter, it must drain completely and thoroughly. In this way, overwatering is avoided and an adequate supply of moisture is ensured.

In addition to optimal irrigation of the Australian chestnut, the plant should also be fertilized at regular intervals. During the main vegetation phase in spring and summer, the plant is supplied with nutrients every four weeks. Liquid variants are preferably used; but chopsticks can also be used. The supply of nutrients usually takes place in the period from April to September, although no additional fertilization is required in the first year after purchasing the plant or after repotting.

The winter of Castanospermum australe takes place in the house in a normal living room and in a light and warm location. During this time, temperatures should not drop below 12 ° C. The plant must also be watered during the winter; However, watering is done less often, as otherwise there is a risk of root rot. No additional fertilization is required during the cold season.

Care also includes rinsing the plant, which should be done once a year during the summer months. This measure serves less to supply moisture than to rinse off dust.

Repotting and pruning

Regular repotting is part of the optimal care of the Australian chestnut; This measure should initially be carried out once a year, then the plant only needs to be repotted every two or three years. The frequency also depends on how the tree is developing and how much space is available for the tree to develop freely. Good quality potting soil is suitable for repotting; it is mixed with cactus soil in a ratio of 1: 1; This creates a permeable soil that minimizes the risk of waterlogging.

Tip: If the Australian chestnut is to be cultivated as a houseplant and kept small overall, you do not need to repot it. In this way, the formation of a compact growth is achieved.

Propagate and plant

Various options are available for cultivating and propagating the plant:

  • Cultivation through pre-grown potted plants
  • Propagation and cultivation via seeds
  • Propagation and cultivation with the help of cuttings

The Australian chestnut is available as a potted plant in the garden center. First, the plant is then transferred to a larger pot, where the best substrate is humus-rich soil. A coaster protects the plant from waterlogging. Now, according to the conditions mentioned above, the plant is cultivated either as a houseplant or outdoors during the summer.

The reproduction of Castanospermum australe via seeds succeeds with a commercially available plant substrate that is mixed with perlite or clay granules. Then the seeds are covered with a layer of substrate, which should be about one centimeter thick. In addition, care must be taken to ensure optimal drainage. Temperatures around 25 ° C have proven to be useful for cultivation, which offer the seed optimal conditions. Similar to beans, care must also be taken to ensure that the seeds are adequately watered so that the seeds sprout quickly. The quality of the seeds used is of particular importance with this possibility of propagation; these must be particularly fresh in any case, as perennial seeds no longer have any germinating power. If the conditions are optimal,

Alternatively, it can also be propagated using cuttings. For a successful cultivation these are put into the soil and kept carefully moist afterwards. When the cutting has gradually grown into a young plant and has developed both leaves and a well-connected root system, repotting can begin. The tree can now be cared for in the same way as the conditions that apply to adult plants.

Australian chestnut diseases

At the moment no special pests are known which preferentially attack the Australian chestnut; the rather hard leaves of the plant are not very attractive to classic insects. Nevertheless, symptoms of illness can occur on the plant, which are then mainly caused by incorrect care. Too much watering quickly leads to waterlogging, which in turn can cause the roots to rot. In this case, the leaves will appear discolored and dry. If the plant is exposed to direct sunlight, the leaves can also become ill. Then the normally dark green leaves appear lighter and bleached by the sun. When healthy, the leaves of the Australian chestnut are dark green and shiny, with the underside appearing matt and light.


If there are pets in the house, gardeners should take extra care when cultivating the Australian chestnut; Both the seeds and the leaves contain a high proportion of saponins, which are toxic to dogs and cats. For this reason it is essential to prevent the animals from nibbling on the plants; If the pets only move inside the house, the chestnut tree can be moved to an inaccessible place in the garden.

Notes on naming

Even if the botanical name suggests the relationship to chestnuts, the plant is a legume that grows from a kidney-like bean and develops edible fruits.

The Australian chestnut is an easy-care plant, the cultivation of which is also becoming increasingly popular in our latitudes. Used in summer as an imposing and decorative shade provider, the plant beautifies any green area. Castanospermum australe also looks extremely decorative as a houseplant. In addition, little experience in gardening is required for successful cultivation, so that even beginners can enjoy the Australian chestnut.

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