How to Grow Potted Fingered Citron? Master These Care Tips

  In recent years, potted fingered citron has become very popular with consumers, and sales have been strong. It is understood that the sales period for fingered citron runs from the 8th lunar month each year to the Spring Festival the following year, after which sales enter the off-season. Over the past two years, fruiting ornamental plants such as kumquat, bitter orange and nianju have been especially popular, with fingered citron the most favored of all. Compared with other Rutaceae flowers, fingered citron sales have remained steady, and prices have shown no obvious rise or fall.

  Fingered citron, also known as jiuzhuamu, wuzhiju and bergamot, generally grows about 1 m tall. It is evergreen year-round, with greenish-yellow fruit shaped like a human hand and a captivating fresh fragrance. It has now become a precious potted ornamental plant grown for both fruit and foliage, and is regarded as the best choice for indoor decoration. Fingered citron likes sun and fears shade, dreads blazing sun and fears severe cold, and is a shallow-rooted, acid-loving plant. Therefore, to keep fingered citron growing attractively, the following care tips should be noted:

  [Watering]

  The most important thing is watering, which is the key to growing fingered citron. Because its roots are shallow and its absorption capacity is relatively weak, care should be taken to water it frequently. During its vigorous growth period, which falls in the high summer heat, it needs a large amount of water; besides watering in the morning and evening, it also needs spraying to increase ambient humidity. After the beginning of autumn, the amount of watering can gradually be reduced. During the low-temperature period in late winter and early spring, when indoor evaporation is slow, water once in the morning every three to five days, just keeping the potting soil moist. During the flowering and early fruiting stages, do not water too much, to prevent heavy flower and fruit drop.

  [Fertilizing]

  Fingered citron likes fertilizer. In spring, when new shoots emerge, fertilizer should be applied lightly. It is best to apply a light nitrogen fertilizer once a week together with watering; summer is the vigorous growth period for fingered citron, with abundant flowers and fruit set, so fertilizer demand is high and the concentration should be increased accordingly. Fertilizers should be based mainly on phosphorus and potassium fertilizers such as cake fertilizer, bone meal, decomposed animal organ liquid or compound fertilizer; from early autumn to mid-autumn, a phosphorus, potassium and calcium compound fertilizer should be applied, which helps improve the fruit-setting rate. In late autumn, after harvesting the fruit, phosphorus and potassium fertilizers should be applied promptly so the plant can replenish nutrients in large amounts, restore its vigor, and lay the foundation for flowering and fruiting the following year.

  [Choosing the Best Fruit-Setting Period]

  Fingered citron blooms most profusely from March to May, but there are many sterile flowers and few fruit-bearing flowers; even if fruit-bearing flowers are retained, they may not set fruit, or may form deformed and defective fruit, or small fruit that does not store well even when ripe. Only from June to before the start of the dog days are the flowers sparse and mostly solitary, with many fertile flowers and a high fruit-setting rate, and the fruit is large, well-formed and plump, all with open "fingers", glossy and attractively colored. Fruit set after the beginning of autumn is also mostly of the closed "fist" type, with poor fruit shape.

  The flowers that fingered citron opens from April to early June are mostly unisexual flowers borne on the previous year's autumn shoots; they cannot set fruit and should all be removed; the flowers that open around late June on the current year's spring shoots are mostly bisexual flowers that can set fruit. Each short branch can retain 1-2 flowers, and the rest should be thinned out to encourage them to grow into large fruit. During the flowering and fruiting period, attention should also be paid to removing new buds sprouting on dry branches to prevent fruit drop.

  [Methods for Preserving Leaves]

  Preventing leaf drop in winter: if the indoor temperature is too high, ventilation is poor, or cold wind blows in when windows are opened, the leaves will "hang" dead on the tree; uneven watering after the plant is brought indoors can also cause leaf drop. There are three methods for preserving leaves:

  (1) Prune spring and summer shoots promptly, and prune once after the beginning of autumn, so that the autumn shoots that emerge can survive the winter.

  (2) The room temperature should be kept at 5-15°C.

  (3) Control watering in winter, keeping the potting soil moisture at around 15%. When it is too dry, first water to about 70 percent, then water again the next day, so that excessive moisture does not push off the leaves.

  [Growing Good Autumn Shoots]

  Fingered citron roots three times and sends out shoots three times a year. Spring shoots grow in the greenhouse; the branches are slender and the leaves large and thin. Except for those kept to fill gaps and support nearby fruiting branches, they should basically not be retained, and should be pruned away in mid-March. Summer shoots sprout around May 1 and are generally not used as the following year's mother branches, so they should be pruned away in mid-June. Only the shoots that emerge after the beginning of autumn are thick and strong, with short internodes, solid tissue and small, thick leaves; except for the thin and weak ones, which are cut off, they can all serve as the following year's fruiting mother branches.

  [Four-Season Management]

  Fingered citron should be moved outdoors from late April to early May, placed in a sunny, wind-sheltered spot. If young leaves are found drooping, water promptly until thoroughly soaked. Before the beginning of spring, water in the morning; after the beginning of spring, water in the afternoon; do not fertilize in winter.

  In summer, when the temperature reaches above 35°C, spray water promptly to keep the potting soil slightly moist, ideally at half moisture; it should not be too wet or too dry.

  From May to June, 1-1.5 kg of cake fertilizer and 4% black alum (ferrous sulfate) can be mixed with 50 kg of water.

  From June to July, 5-7.5 kg of cake fertilizer and 5% black alum mixed with 50 kg of water can be used; in August, 10 kg of cake fertilizer and 6% black alum mixed with 50 kg of water can be applied separately as liquid fertilizer (the liquid fertilizer should be composted for at least 2 months; the longer, the better). Note that it must not be applied when the plant has just sprouted, to avoid damaging new roots; stop fertilizing when the autumn shoot buds have formed plumply, to prevent new shoots from sprouting again and wasting nutrients.

  After Frost's Descent, move the plant indoors, keep the temperature at 5-15°C, place it where sunlight can reach it, and pay attention to opening windows for ventilation. Every 2-3 days, spray the leaf surface with 10°C warm water, keep the potting soil humidity at around 50%, and water promptly when it dries out.

  [Pest Prevention]

  Fingered citron is mainly affected by aphids, red spider mites, cottony cushion scale and the like. In winter, when temperatures are low, the plant should be moved to a sunny spot to raise the temperature and prevent frost damage. The main diseases and pests of fingered citron include anthracnose, scab, sooty mold, as well as citrus leafminer, scale insects and red spider mites, which should be controlled promptly. Red spider mites and aphids damage leaves, flowers and young fruit, and can be controlled by spraying a 1000-fold dimethoate solution; cottony cushion scale can be controlled with a 1000-fold 25% amiton solution or by hand-catching the adults.