What are the cultivation methods and precautions for bonsai kumquat?

Kumquat, with aliases such as yangnai kumquat, orange tree, milk kumquat, golden jujube, golden pellet, golden elixir, golden citrus, Mashui kumquat, kumquat, and golden orange, belongs to the genus Fortunella in the family Rutaceae and is a well-known ornamental fruiting plant. Especially in Guangdong and Hong Kong, China, many residents buy it during the Spring Festival for good luck. The kumquat is an evergreen shrub. Flowers are solitary, white, and fragrant. The fruit is mostly oval, golden yellow, and glossy; some varieties are edible, and it is mostly propagated by grafting.

The following points generally need attention when cultivating kumquat:

1. Temperature:

The suitable temperature for kumquat growth is 22-29°C, and the most suitable indoor display temperature in the north is 10-15°C. If the plant is still small and has not borne fruit, the overwintering humidity is 3-5°C, and it should not exceed 10°C, otherwise dormancy will be affected. When the outdoor temperature rises back to 10°C at night, move it outdoors for care and strengthen ventilation and light. After autumn turns cool, move it back indoors.

2. Light

Kumquat is a light-loving plant. During the growing period, place it in a sunny spot. In hot summer with intense sun, it can be slightly shaded. When viewing the fruit in winter, place it in a bright indoor spot. For dormant small plants, winter light requirements are not strict.

Kumquat prefers a warm and humid climate with plenty of sunlight, and should be placed in a sunny place during care. If light is insufficient and the environment is shady, it often causes excessive growth of branches and leaves and fewer flowers and fruits. Because kumquat prefers a cool climate in summer, or when summer sunlight is intense, it is better to place it in slight shade at this time. The winter room temperature should be above freezing. If the room temperature is too high, the plant cannot fully enter dormancy, and then growth will be weak the next year, making it prone to flower and bud drop.

After March, most of the kumquat fruits fall naturally. Remove the remaining fruits by hand to save nutrients. At the same time, thin out overly dense branches, crossing branches, some leggy branches, and inner branches that receive no light. Heavily short-cut the retained 1-year-old branches, leaving 2-3 buds per branch, with the cut bud facing outward, so that the crown opens up and allows ventilation and light.

During the flowering and fruiting period, pay attention to thinning flowers and fruits, keep the earlier-opening flowers, and remove late and weak flowers. The flowers that generally open from May to June have a relatively high fruit-setting rate and should be retained more. Remove flowers and fruits after July.

3. Potting:

Kumquat originates in the subtropics and prefers slightly acidic soil. When repotting in spring, keep part of the soil ball to protect the roots and prune excess old roots. Place two pieces of horsetail at the bottom of the pot, and above that fill a mixture of decomposed sawdust and an equal amount of garden soil, or a mixture of 8 parts loose, fertile soil rich in humus plus 2 parts cinder.

4. Skillful pruning

Pruning is an important technical measure to make kumquat bloom abundantly and bear many fruits. To make the tree shape beautiful and bear more fruit, before the sap begins to flow each year and before spring buds sprout, carry out one heavy pruning, cutting off dead branches, diseased and pest-damaged branches, overly dense branches, and leggy branches, retaining 3-4 robust, evenly distributed branches from the previous year, leaving only 2-3 buds at the base of each branch and cutting off the rest. In this way, more than 10 full spring shoots can sprout. When the new shoots grow to 15-20 cm, pinch off the tips to make the plant shape full. At this time, apply a quick-acting phosphorus fertilizer once to promote flower bud differentiation.

During flowering, thin the flowers appropriately to save nutrients. After young fruits are set, when the young fruits grow to about 1 cm in size, fruit thinning can be carried out. Leave 2-3 fruits per plant on thick branches, and keep one fruit per weak branch, and make the fruits on the whole plant uniform. Promptly cut off autumn shoots so as not to let it bear fruit a second time, so as to benefit uniformity of fruit shape, size, and ripeness and improve ornamental value.

5. Water well

Kumquat likes moisture but fears waterlogging, and overly wet potting soil easily causes root rot. Therefore, during the growing period, it is better to keep the potting soil moderately moist. Spring is dry and windy. It is necessary to spray water on the leaf surface once a day to increase air humidity. In summer, spray water 2-3 times a day and also spray water on the ground. But avoid spraying water during the flowering period to prevent flower rot and affect fruit set. In the rainy season, promptly pour out accumulated water in the pot to avoid root rot. When placed outdoors in summer, it is best to prop up the flowerpot with bricks to facilitate drainage. From the white flowering stage to the young fruit stage, kumquat is more sensitive to water requirements. At this time, if the potting soil is too dry, the pedicel and fruit stalk easily form an abscission layer and drop; if watering is excessive and the potting soil has poor drainage, it also easily causes flower and fruit drop. Therefore, at this time it is suitable to keep the potting soil in a state of neither dry nor wet.

For watering, master the principle of watering when dry and letting it dry between waterings, and watering thoroughly when watering. During the flowering period, the potting soil should be slightly dry. After fruit set is stable, water normally. If the young fruits are as large as soybean grains, fertilizer and water can be increased. Kumquat likes a humid environment. During the display and ornamental period and the peak growing season, water should often be sprayed on the leaves and around the flowerpot, but never spray on the flowers during the flowering period to avoid flower rot. For plants dormant at lower temperatures, control watering.

6. Apply sufficient fertilizer

Kumquat likes fertilizer. When potting, it is advisable to choose a culture soil mixed with 4 parts leaf mold, 5 parts sandy soil, and 1 part cake fertilizer. When repotting, apply horsetail or decomposed cake fertilizer at the bottom of the pot as a base fertilizer. From the beginning of new bud sprouting until before flowering, apply decomposed dilute soy sauce residue water once every 7-10 days, alternating with several applications of alum fertilizer water. It is also possible to apply decomposed sesame paste residue or compound fertilizer under the dry surface soil, then water immediately.

Note that fertilization should be in small amounts and multiple times. Organic fertilizer must be fully decomposed. The interval between applications of solid fertilizer is generally 1 month. Do not fertilize during the winter fruit-viewing period. After early summer, it is better to apply more phosphorus fertilizer to benefit bud formation and fruiting. At the early fruit stage, fertilization should be paused. When the young fruits grow to about 1 cm in size, continue applying liquid fertilizer once a week until the end of September.

7. Pest and disease control:

The main dangerous pests of kumquat include aphids, scale insects, and red spiders, which can be controlled with a solution of 40% omethoate emulsifiable concentrate at a mass fraction of 0.067%, or a solution of 40% Supracide at a mass fraction of 0.67%. Kumquat is an acid-loving flower, and in the north there is often chlorosis due to iron deficiency. When preparing the culture soil, a small amount of ferrous sulfate can be added, or during the growing season the leaves can be sprayed with a 0.1% ferrous sulfate aqueous solution once every 15-20 days. Or add a few drops of vinegar when watering, or regularly water with alum fertilizer water containing 1% ferrous sulfate. Under poor ventilation and poor light, kumquat may develop sooty mold and powdery mildew, which can be controlled with a 0.125%-0.142% solution of 70% thiophanate-methyl.