This Australian native Finger Lime Citrus australasica is one of the best kept secrets of the restaurant trade. The flesh looks like caviar and the intense bursts of lime freshness not only taste sensational but come in an array of colours ranging from intense red through to ruby pink and subtle shades of green.
These understory trees are native to coastal rainforests in northern NSW and south-east Queensland. In their natural habitat they compete in the sub-canopy for light and nutrients and will grow to between 2-6 metres high. In its natural habitat it may only bear fruit after many years or when under stress. However, when grafted to a citrus rootstock the tree will grow larger and become much more productive. Some varieties are even known to fruit all year round.
I spoke to a Northern NSW grower Fred Durham of the Australian Finger Lime Company who grows over 2000 trees in his orchard. His first tip for growing these trees are that they are thorny so be careful where you plant them. One advantage of the thorny nature of this bush is that they make wonderful habitat for small birds such as the superb fairy wren.
Fred is very conscious of reducing his carbon footprint to offset the cost of flying his produce to places like Paris, North America and Japan. He is very careful to use natural rather than artificial methods to feed his trees. So his second tip is that mulch is an extremely important way of feeding the trees. Use low protein and high carbon woody mulches to promote fungal domination in the soil.
Mycorrhizal fungi help plants to capture macronutrients and micronutrients from the soil by using a loose network of hyphae, (delicate, microscopic, cobweb-like threads). Each fungus will have vast numbers of these hyphae, all intertwining and helping to bind soil particles, contributing to soil structure and erosion control. In this symbiotic relationship the fungi feed the plant and in return the plants provide carbohydrates for the fungi. Pathogenic organisms are also less abundant in soil with plenty of mycorrhizal fungi. Avoid artificial fertilisers, tilling and hoeing the soil as these can destroy the fungi.
Fred has access to a huge supply of mulched eucalyptus trees that are being removed to make way for a highway in his area. Ensure that the mulch is added to a depth of 5-7cm and it should not be applied too close to the trunk of the tree as this can cause collar rot. You need to ensure the trees have plenty of water especially when flowering or growing fruit. Give your tree a light pruning each year aiming to remove any dead wood. Prune some minor branches to prevent over-crowding and this will allow sunlight and air to circulate within the tree canopy and give access to your biological sprays to control scale insects.
The tree requires good drainage with full sun being suitable for dark skinned varieties while pink skinned varieties would benefit from some semi-shade to reduce sunburnt fruits. It also needs protection from strong winds as these may cause the flowers and fruit to blow off reducing your crop and also reducing fruit rub against thorns. It prefers soil with a pH of between 5.5 and 6.5. The trees are often slow growing for the first 12 months until established. As finger limes are grafted to compatible modern day commercial rootstocks they can grow in a range of soil types that have good drainage.
Most of the Finger Lime varieties being sold at Nurseries come from wild trees and have qualities that are attractive to reproduce; such as great tasting fruit and a variety of colours. Originally bud-wood from these ancient wild trees was grafted on to modern day Citrus rootstock to give nurseries a collection of stock-trees and a source of continual grafting bud-wood.
Sources of these trees are :
If you want to try out this Australian gourmet bush food then Finger lime fruits are available from Mid January to May from most Ritchies-Supa IGA Stores
For more information then check out www.australianfingerlime.com of Fred Durhams’s Australian Finger Lime Company.
Here are some Finger Lime recipes: