A Detailed Guide to the Cultivation and Growing Methods of the Bitter Orange (Citrus aurantium var. amara)

SummarySelection of potting soil and seedlings: choose a purple clay (zisha) flower pot with good permeability; select plants with a relatively vigorous root system and robust growth; the soil should be loose, fertile, nutrient-rich and well-draining. Potting: repot in early March to April or in October to November. Reasonable watering and fertilizing: in summer and autumn, appropriately increase the amount and frequency of watering; in spring and winter, water sparingly; fertilizer should be applied in small amounts but frequently. Repotting, root pruning and branch pruning: prune the roots appropriately, and train the branches according to bonsai shape and flowering and fruiting requirements.

I. Selection of potting soil and seedlings

1. Before planting, first choose the flower pot; select a purple clay (zisha) flower pot that is attractive and elegant with good permeability, and its size should match the size of the plant so that the plant's root system can fully spread out.

2. Select plants that are relatively robust in growth, have a relatively vigorous root system, evenly distributed lateral roots and relatively many fibrous roots for planting. The soil should preferably be a slightly acidic mountain yellow loam that is fertile and loose, well-draining, well-aerated and rich in nutrients and organic matter.

II. Potting

1. Bitter orange is generally potted in early March to April in spring or in October to November. First place some broken tile pieces over the drainage hole at the bottom of the pot, pour in a small amount of potting soil, then place the plant into the pot; it is best to transplant it with the soil ball, then cover with potting soil.

2. First hold the plant upright, then firm down the potting soil around the seedling roots so that the roots make close contact with the soil. Fill the pot with soil to about 80% full, water thoroughly to settle the roots, and place it in a spot with scattered light for care. Keep the soil moist and avoid direct strong sunlight and heavy rain.

III. Reasonable watering and fertilizing

1. For potted bitter orange, during high summer temperatures and autumn droughts, appropriately increase the amount and frequency of watering; in winter and spring, water sparingly. Each watering should soak the potting soil through, until water seeps out from the bottom of the pot, and water again only after the surface of the potting soil has dried and turned pale. In rainy seasons, do not leave it exposed to rain for long periods, so as to avoid excessively high soil moisture that can cause root rot and plant death.

2. Fertilize bitter orange on the principle of small amounts applied frequently. In early spring and in autumn and winter, apply organic fertilizers such as rapeseed cake or slightly acidic compound fertilizer. During the growth and flowering and fruiting periods, foliar topdressing can be carried out by appropriately spraying some plant nutrients that promote flowering and fruiting. Do not apply excessive nitrogen fertilizer, as it easily causes excessive vegetative growth and leads to flower and fruit drop.

IV. Changing potting soil, root pruning and branch pruning

1. Potting soil is generally changed in early spring and late autumn. Because bitter orange grows relatively vigorously and has a very developed root system, it needs to be repotted and have its soil changed about once every 1-2 years.

2. When repotting, prune the roots and train the branches: cut off all the roots coiled around the inner wall of the pot, then appropriately cut back overly long main roots and lateral roots, keeping about one third of the fibrous roots.

3. To make the bitter orange's tree shape attractive, appropriately train the branches. Train the branches according to bonsai shape and flowering and fruiting requirements: first cut off thin and weak branches and aged branches, and at the same time cut back prominent scaffold branches and water sprouts. This helps promote crown renewal and also controls plant size, thereby achieving the effect of shaping an attractive tree form.

V. Pest and disease control

The main pests and diseases of bitter orange include sooty mold, mite damage, leaf spot disease, scale insects and whiteflies. Control measures can include manual capture, scraping off by hand, cutting off diseased and pest-infested branches, or using agents such as chlorothalonil and thiophanate-methyl.