Calamondin: growing & caring for calamansi trees

Since citrus plants come from warmer climates, caring for them in this country is not that easy. Beginners can enter the world of citrus with the slightly smaller, but easy to care for calamondin oranges.

The small-fruited calamondin orange tree (Citrofortunella microcarpa) delights garden enthusiasts with its ornamental fruits. These develop in large numbers on the plant and can then be harvested. The tree is kept as a pot or container plant, which spends the summer on the sunny terrace or balcony. It is equally suitable as a houseplant.

Calamondin: origin and characteristics

The calamondin orange, also known as calamansi or by the botanically obsolete terms Citrus mitis and Citrus madurensis is a natural hybrid, probably originating in China, between the mandarin orange (Citrus reticulata) and a species of kumquat (Fortunella sp.). The calamansi tree is widespread, especially in East Asian and Caribbean areas, where the fruits are increasingly cultivated. Since the small calamondin oranges are completely edible and have a very acidic taste of their own, the fruits are often used in Filipino or Malaysian cuisine, for example, to make spices, jams, vinegars or lemonades. The plant grows as an evergreen perennial tree and has lanceolate to ovate leaves. In its native country, the calamondin tree grows up to 8 m tall, while in this country, kept in tubs, it only reaches barely 2 m tall.

Planting calamondin: location and procedure

Unfortunately, since the calamondin orange comes from warmer climates, it cannot be planted directly outdoors in our latitudes. Instead, it must be kept as a container plant and overwintered or placed in a heated greenhouse or conservatory. Like most citrus plants, the calamondin orange prefers a very sunny location. If there is not enough sunlight reaching the plant, especially during overwintering, additional exposure with plant lamps can be of great benefit. For example, if the calamansi tree is located in a bright south-facing window, no additional lighting is needed. With sufficient light, calamansi can be kept as a houseplant year-round, but it is much better to place the plant outside in a sunny location during the summer months. As a substrate is suitable slightly acidic, permeable soil, because the calamondin tree does not tolerate waterlogging. For example, a mixture of our peat-free Plantura Organic All Purpose Compost with an admixture of about one-third sand or other mineral granules provides a structurally stable composition, which is important to prevent compaction of the substrate.

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At a glance: Planting calamondin oranges

• Pot: Much larger and with drain hole
• Fill in drainage layer at the bottom, for example, gravel, expanded clay, clay shards
• Prepare substrate mixture: Nutrient-rich, slightly acidic potting soil and 30% structural material such as expanded clay
• Pour in some substrate, insert calamondin plant, fill up at the edge and press down
• Cover root ball only thinly with a layer of soil, do not plant too deep
• Water
• Apply mulch layer

Calamondin care

When caring for calamansi, there are some points you should pay attention to so that the citrus plant grows well.

Pruning calamondin trees

To keep the calamansi tree in shape and healthy, regular pruning is necessary. However, since the plant grows quite slowly, this maintenance pruning is not necessary too often. The best time for this is the spring just before new shoots, ideally close to repotting. Using a sharp and clean tool, remove all diseased, crossing and inward branches at the base. Shorten branches that are too long with a slightly diagonal cut above a bud that points outward. Since the calamondin always flowers at the tips of the branches, regular pruning is a good way to stimulate growth and branching to ensure abundant fruiting. However, do not cut too many branches so as to leave some flower buds for the coming flowering.

Watering and fertilising

Depending on the size of the pot, the season, the soil used and the location, the watering frequency will naturally be different. The best way to feel how dry or moist the substrate is at the moment is with a finger in the soil. In general, the calamansi can manage with a little less water, but should never be placed in completely dry soil. So on hot and sunny summer days, even daily watering can be useful, but in winter watering is almost never required.
In addition to the correct watering of the citrus plant we should point out that lime water is not ideal, because the plant likes it rather slightly acidic. Therefore, in areas with particularly hard tap water, rainwater should be used or the water should be decalcified with appropriate filters.

To provide the calamondin tree and its fruits with sufficient nutrients for healthy growth, a special fertiliser for citrus plants, such as our Plantura Liquid Citrus Food is ideal. The liquid fertiliser is easy to use, as it is simply added to the water.

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Tip: Many liquid fertilisers are phosphate-reduced to conserve the world’s phosphorus supplies. So is our Plantura Liquid Citrus Food. Long-term cultivation of citrus plants in the same substrate may possibly result in phosphate deficiency. To prevent this, we recommend spreading a primarily organic complete fertiliser such as our Plantura Flower Food under the mulch once a year in addition to liquid fertilisation. This tailored fertilisation is good both for the plant and the environment.

Repotting

To allow the calamansi to grow healthily, it must be planted properly for its species and repotted from time to time. Due to its slow growth, the calamondin orange only needs repotting every 3 to 4 years, provided that a sufficiently large pot and a structurally stable substrate have been chosen. At the latest, when the whole planter is firmly rooted, it’s time to repot. Choose the spring as the time, just before the new shoots. Remember to reapply mulch to the root disc after repotting.

Calamondin tree is losing leaves: what to do?

If the calamansi is losing leaves, there are several reasons for this:

• Location too dark: If the calamondin has too little light, leaves facing away from the sun may fall off, so the plant should be placed as brightly as possible and turned occasionally.
• Nutrient deficiency: Inadequate nutrients can cause the calamondin tree to turn yellow and then lose leaves, so regular repotting and fertilising are extremely important.
• Water shortage or waterlogging: In addition, if the plant is watered too much or too little, leaves may also fall off, so the humidity of the substrate must be checked regularly.
• Wintering incorrectly: Too little light or too much water can have a bad effect on the plant, especially during wintering. Read more about wintering below.
• Diseases and pests: Other causes are diseases and pests. Especially in dry summers, but also in winter, spider mites often appear. Especially during the wintering indoors, scale insects are often found. Therefore, the calamansi should be examined for it at defined intervals. If diseased or infested shoots are discovered, they should be removed or treated with appropriate plant protection measures.

Overwintering calamansi trees

The calamansi tree is not hardy, so it must be kept away from temperatures below zero. It is best to overwinter calamondins in a bright and cool location. A temperature of 5 to 10 °C would be ideal for this, but the plant can be overwintered even at room temperature. It is important to ensure that the plant is kept in as much light as possible.

Harvest and use: is the calamondin edible?

When ripe, the fruits are bright orange in colour and edible together with the skin, which has little effect on the taste. In general, however, the calamansi fruit is quite acidic when eaten, but is well suited for making calamondin jam or other products, such as syrup or other beverages. In addition, the fruit is an excellent seasoning. The juice is ideal for marinating poultry or fish. Furthermore, the calamansi is often processed in the haute cuisine to a gel, which is used to garnish a variety of dishes.

Citrus calamondin can actually be harvested all year round, although most of the fruit ripens in the summer, of course. So between about July and September, most calamondin oranges can be enjoyed fresh from the tree, providing not just a visual but also a culinary delight.

For harvesting, ideally remove the fruit together with the fruit stalk. For this purpose, use sharp and clean scissors. If you simply pick the small oranges from the tree, sometimes peel residues remain, which can then have negative effects on plant health.

The nectarine tree has a similar climate preference to the calamondin tree. However, unlike calamondin oranges, the trees can be planted directly in the garden in suitable locations.