establish and for the first 12 months after planting there is little sign of any growth. Applying mulch around young trees will help to retain soil moisture and keep roots cool. Keep the mulch well away from the tree trunk to prevent collar rot. Removing fruit for the first three years after planting will help to improve tree growth and establishment.
Most commercial plantings use a hedgerow system with the tree rows running in a north-south direction to maximise light interception. Planting densities vary with cultivar, but spacings of 2.5–3 m between trees and 4–5 m between rows are common. This equates to around 600 to 800 trees/ha. It is best to plant only the one cultivar of finger lime within a row for easier management and harvest operations. The number of trees planted and cultivar selection should always be based on market requirements. Most commercial plantings are 100–300 trees. Flowering and cropping. Grafted finger lime trees begin fruiting in year three but larger quantities of fruit are not normally obtained until year six, when trees are classed as ‘bearing’. Seedling trees can take up to 15 years to produce fruit, depending on cultivar. Most cultivars consistently bear fruit every year; however, some cultivars are prone to biennial bearing and a few tend to crop up to 3 times a year.
On the north coast of NSW flowering starts in June and extends through to early October, depending on cultivar. In warm coastal regions trees may also flower sporadically throughout spring and summer. Depending on climatic conditions and cultivar, fruit mature between December and May, with the main harvest period occurring between March and May. Fruit are selectively picked every 10–14 days over a 6–8 week period depending on tree age and cultivar.
Finger limes have a fruit development period of around 5 months from flowering to harvest. As with other citrus varieties natural fruit drop will occur early in the season as the tree sets more fruit than it can carry and fruit may also be shed during very hot, dry or windy conditions. Some thinning of fruit clusters to improve fruit size is undertaken on heavy setting cultivars.
Yields vary with cultivar, but well managed 5–6 year old trees can produce up to 20 kg annually. It is important to remember that only about 40% of the fruit produced will be 1st grade/export quality, with the remaining fruit being either 2nd grade or processing quality. Finger lime trees because of their habit and thorniness tend to have a high percentage of 2nd grade or processing fruit. Fruit range in size from 6–12 cm and individual fruit can weigh up to 60 g. Nutrition. No specific research work has been undertaken on tree nutrient requirements, however finger limes are reported to require a lot less fertiliser than other commercial citrus varieties. This is probably due in part to less demand by the tree because of its naturally smaller leaves and canopy area. Growers are using only about 25–30% of the total annual amount of NPK fertiliser applied to other commercial citrus varieties. Depending on growing conditions the roots of finger limes in cultivation tend to have a more fibrous root system with the majority of feeder roots usually in the top 30–60 cm of soil. A complete NPK (15:4:11) fertiliser low in phosphorous is currently being used by commercial growers. No fertiliser should be applied from flowering up until fruit are 1 cm long, otherwise fruit have a tendency to abort. Some growers apply foliar fertilisers to trees prior to flowering if required. It is best to apply fertiliser