The bilimbi or cucumber tree is not one fruit tree that you want to grow if you are into sweet dessert fruits. Its fruits are extremely acidic and tard and are used in South East Asian cuisine to provide that kick of sourness. The fruit of bilimbi is used for pickles, curries, chutney and preserves in syrup. Interestingly, its fruits are used to clean metal and remove stains, most likely due to their high citric acid content. They are also used in traditional medicine to treat skin disorders and fevers, accordingly to Plant Resources of South East Asia (PROSEA). The genus name is after Averrhoes (1126-98), the widely known Arab philosopher.
A relative of the starfruit (also known as carambola), the bilimbi is botanically known as Averrhoa bilimbi. Both fruit trees are members of the Oxalidaceae family. The exact origin of the bilimbi is not certain, although it has been suspected to be from South East Asia. Averrhoa bilimbi grows as a small tree, reaching to heights of about 10 m. Its leaves are pinnate with the young ones taking on an attractive, bronzy colour. The tree has a short trunk with a few upright branches. This fruit tree produces clusters of attractive, fragrant, star-shaped red flowers on its trunks and branches, which is a habit termed as cauliflory. The fruits are cucumber-like albiet smaller – nearly cylindrical in shape (but one can still see the faint five ridges seen more prominently in its starfruit relative). The fruit is crisp when unripe, turns from bright-green to yellowish-green, ivory or nearly white when ripe, depending on the cultivar.
Averrhoa bilimbi is a tropical tree that grows well in areas with a distinct dry period. It has a high water requirement but prefers a well-draining location with slightly acidic soil to grow well soils. It does not tolerate winds, drought, flooding and salinity. The tree thrives in full sun and does not grow well in shady or semi-shady situations. Plants are usually raised from seeds although sometimes propagated via air-layering (marcotting). Mature plants are self-fertile, flower and fruit continuously, but usually there are one or two pronounced harvest seasons. Flowers are documented to open in the morning and fruit set is quite heavy.
The fruits are usually picked by hand, singly or in clusters. Note that they need gentle handling because of the easily bruised, thin skin. They do not have a long shelf-life – pick as required for the kitchen as they cannot be kept for more than 4 to 5 days under ambient conditions. To reduce acidity, fruits may be first pricked and soaked in water overnight, or soaked in salted water for a shorter time. The treated fruits are then boiled with sugar to make a delicious jam. Half-ripe fruits are sometimes salted, set out in the sun and then pickled in brine.
No pests or diseases have been reported specifically for the bilimbi as long as a tree is grown in a well-draining location. Grow this tree in your garden in if have the space to appreciate its attractive flowers and provide food for the flying jewels in our gardens – the butterflies, as well as, birds and bees. Read the blog post below for more information: