Citrus japonica (Kumquat)

Remarkably cold-hardy, Kumquat (Citrus japonica) is a small to medium-sized evergreen tree prized for its glossy lance-shaped leaves and very small, oval, orange fruits.

What is a Kumquat?

Description: Kumquat (Citrus japonica) is a small to medium-sized, evergreen fruit-bearing tree or shrub in the citrus family, Rutaceae. Native to Southern China, it produces small, oval to round, brightly colored orange fruits that are both sweet and tangy. The fruits have a unique characteristic where the skin is sweet, and the flesh is sour.

Growth habit: Kumquat trees have a dense, bushy growth habit with a rounded canopy. They can be grown as specimen plants, in containers, or as part of an orchard.

Size: Kumquat trees typically grow to a height and spread of 8-15 feet (2.4-4.5 meters), depending on the variety and growing conditions.

Flowers: The flowers of kumquat trees are small, fragrant, and white, resembling those of other citrus plants. They shine against the foliage of shiny, dark green, evergreen leaves.

Blooming season: Kumquat trees usually bloom in late spring or early summer, with some varieties producing flowers sporadically throughout the year. The flowers are self-fertile and require no cross-pollination. They are followed by fruits in late winter that hold well on the tree.

Fruits: Kumquat fruit is a small, oval to round-shaped citrus fruit, typically around 1-2 inches (2.5-5 cm) in length. The fruit is bright orange when ripe and has thin, sweet, edible skin and tangy, slightly sour flesh, creating an interesting flavor combination. The fruit can be eaten whole, including the skin, which offers a burst of flavor and aroma. The texture of the skin is somewhat similar to that of an orange but thinner and smoother. Inside the fruit, there are seeds, which can be easily removed or spat out when eaten.

Hardiness: Kumquats are hardy in USDA zones 9-11. They are more cold-tolerant than most other citrus plants but still need protection from frost.

Uses: Kumquats are primarily grown for their edible fruits, which can be consumed fresh, candied, or used in marmalades, jams, and desserts. The fruit is also used in cocktails and savory dishes. In addition, kumquat trees are often grown as ornamental plants for their attractive appearance and fragrant flowers.

Award: Recipient of the prestigious Award of Garden Merit of the Royal Horticultural Society.

Toxicity: Kumquat fruits are non-toxic and safe for human consumption. However, like other citrus plants, kumquat leaves and stems contain compounds that can be toxic to pets if ingested in large quantities.

Why Should I Grow a Kumquat Tree?

There are several reasons to consider growing a kumquat tree:

Unique, flavorful fruit: Kumquats offer a unique taste experience with their sweet, edible peel and tangy flesh. They can be eaten fresh, added to fruit salads, or used in various culinary applications like marmalades, jams, preserves, and desserts.

Ornamental value: Kumquat trees are attractive, with glossy green leaves, fragrant white flowers, and eye-catching, brightly colored fruits. They can enhance the visual appeal of your garden, patio, or even indoors when grown in containers.

Cold-tolerant citrus: Kumquats are among the most cold-tolerant citrus plants, making them a suitable option for gardeners living in cooler climates where other citrus species might struggle.

Compact size: Kumquat trees are relatively small, making them ideal for smaller gardens, urban spaces, or container gardening. Their size also makes them easier to maintain and harvest compared to larger fruit trees.

Self-pollinating: Kumquat trees are self-fertile, meaning they can produce fruit without the need for another tree for cross-pollination. This makes them a great option for gardeners with limited space or those who want to grow just one fruit tree.

Health benefits: Kumquats are rich in vitamin C, antioxidants, and other nutrients, contributing to a healthy diet and supporting the immune system.

Low maintenance: Once established, kumquat trees require relatively low maintenance. They need occasional pruning to maintain their shape and size, and they are moderately drought-tolerant.

Pest resistance: Kumquat trees are generally resistant to common citrus pests, which means they often require less pesticide treatment than other fruit trees.

Indoor gardening option: Kumquat trees can be grown indoors in containers if provided with sufficient light and proper care, allowing you to enjoy the benefits of a fruit tree even if you don’t have an outdoor garden.

Overall, a kumquat tree can be a versatile, attractive, and rewarding addition to your garden or indoor space.

Kumquat: Nutrition and Health Benefits

Kumquats are packed with various nutrients and offer several health benefits. Here are some of the key nutritional components and health benefits of kumquats:

Vitamin C: Kumquats are an excellent source of vitamin C, which is essential for a healthy immune system, helps the body absorb iron from plant-based foods, and acts as an antioxidant to protect cells from damage caused by free radicals.

Dietary fiber: The fruit is a good source of dietary fiber, which aids digestion, helps maintain regular bowel movements and may lower the risk of developing certain diseases like heart disease and diabetes.

Antioxidants: Kumquats contain various antioxidants, including flavonoids, carotenoids, and tannins, which help protect the body from oxidative stress and may reduce the risk of chronic diseases like cancer and cardiovascular disease.

Vitamin A: Kumquats contain modest amounts of vitamin A, which is essential for healthy vision, skin, and immune function.

B Vitamins: The fruit contains some B vitamins, such as thiamin, riboflavin, niacin, and vitamin B6, which are vital for energy production and maintaining a healthy nervous system.

Minerals: Kumquats provide a range of essential minerals, including potassium, calcium, magnesium, and phosphorus. Potassium is crucial for maintaining proper fluid balance, nerve function, and muscle contractions, while calcium is necessary for strong bones and teeth.

Low in calories: Kumquats are low in calories, making them a suitable snack for those watching their calorie intake.

Heart health: The combination of fiber, potassium, and antioxidants in kumquats may contribute to better heart health by reducing cholesterol levels, blood pressure, and inflammation.

Blood sugar control: The fiber in kumquats can help slow down the absorption of sugar into the bloodstream, which may benefit those with diabetes or looking to maintain stable blood sugar levels.

While kumquats offer numerous health benefits, it’s important to remember that consuming them as part of a balanced, varied diet is essential to maintaining overall health and well-being.

How to Eat Kumquat?

Kumquats can be enjoyed in various ways, thanks to their unique flavor and edible peel. Here are some ideas on how to eat kumquats:

Fresh and raw: The simplest way to enjoy kumquats is to eat them fresh and raw. Wash the fruit thoroughly, then pop it in your mouth whole, or slice it in half if you prefer. The sweet, edible skin and the tangy flesh create a delightful contrast of flavors.

Remove the seeds: If you find the seeds bothersome, you can slice the kumquat in half and remove the seeds before eating.

In salads: Add kumquats to fruit or green salads for a burst of color and a sweet-tangy flavor.

As a garnish: Use sliced kumquats as a garnish for cocktails, desserts, or savory dishes to add a pop of color and flavor.

In preserves and marmalades: Kumquats are ideal for making preserves, marmalades, and jams, thanks to their natural pectin content and mix of sweet and tangy flavors.

Candied: Make candied kumquats by simmering them in sugar and water until they become translucent and sweet. Candied kumquats can be enjoyed as a treat or used as a garnish for desserts.

Baked goods: Incorporate kumquats into cakes, muffins, or tarts for a unique citrus flavor.

In savory dishes: Kumquats can be used in savory dishes like stir-fries, sauces or as a garnish for roasted meats.

Beverages: Use kumquats in cocktails, smoothies, or fruit-infused waters for a refreshing and flavorful twist.

Remember to wash kumquats thoroughly before eating, as they are often treated with pesticides or wax coatings to preserve freshness and appearance.

How to Grow and Care for Kumquats

Growing and caring for kumquat trees can be a rewarding experience, as they are relatively low-maintenance and produce delicious, attractive fruit. Here are some guidelines on how to grow and care for kumquats:

Select a suitable location: Kumquats need full sun and well-draining soil. Choose a sunny spot in your garden (protected from strong winds) or a south-facing window for a potted tree. Ensure the soil is well-draining to prevent root rot.

Planting: If planting in the ground, dig a hole twice the width and depth of the tree’s root ball. Gently loosen the roots, place the tree in the hole, and backfill it with soil. Give your kumquat tree at least 5-6 feet (1.5-1.8 meters) of space so that it has enough room to grow. For potted trees, choose a large container with drainage holes and fill it with a well-draining potting mix.

Watering: Kumquats need consistent moisture, especially during the growing season. Water the tree deeply and regularly, allowing the soil to dry slightly between waterings. Avoid over-watering, as this can lead to root rot.

Fertilizing: Apply a balanced, slow-release citrus fertilizer during the growing season, following the package instructions for application rates and frequencies. In addition, you can supplement with a foliar spray containing trace elements like iron, zinc, and manganese. Do not fertilize in the winter.

Pruning: Prune kumquat trees to maintain their shape and size and to remove any dead or damaged branches. Prune lightly after the fruiting season or in early spring before new growth begins.

Frost protection: Kumquat trees are more cold-tolerant than other citrus trees and can withstand 18°F (-8°C) of frost without injury. However, they still need some protection from freezing temperatures. If a frost is expected, cover the tree with a frost cloth or move potted trees indoors.

Harvesting: Kumquats are typically ready to harvest in late fall or winter. The fruit should be bright orange and slightly soft to the touch. Gently twist the fruit off the tree or use pruning shears to avoid damaging the branches.

With proper care, your kumquat tree will provide you with a bounty of fresh, flavorful fruit for years to come.

How to Propagate Kumquat

There are a few methods to propagate kumquat trees, including seeds, cuttings, and grafting. Here’s a brief overview of each method:

Seeds

• Harvest seeds from a ripe kumquat fruit.
• Rinse the seeds thoroughly to remove any fruit residue and let them dry for a day or two.
• Fill small pots or seed trays with a well-draining seed-starting mix.
• Sow the seeds about 1/4 inch deep and cover them with the soil mix.
• Water the seeds and keep the soil consistently moist but not soggy.
• Place the pots in a warm, sunny location or use a heat mat to maintain a temperature of 70-75°F (21-24°C).
• Germination may take several weeks. Once seedlings have developed a few sets of true leaves, transplant them into larger pots.

Keep in mind that kumquats grown from seeds may not produce fruit identical to the parent plant due to genetic variation.

Cuttings

• Take 4-6 inch (10-15 cm) long cuttings from a healthy kumquat tree during its dormant period.
• Remove the leaves from the bottom half of the cutting.
• Dip the cut end in rooting hormone to encourage root development.
• Fill small pots with a well-draining potting mix.
• Insert the cuttings about 2 inches (5 cm) deep into the soil.
• Water the cuttings and cover the pot with a plastic bag or clear plastic container to create a humid environment.
• Place the pot in a warm, bright location, but avoid direct sunlight.
• Keep the soil moist but not soggy, and maintain high humidity.
• Roots should develop in 4-6 weeks. After that, remove the plastic cover and gradually acclimate the cuttings to regular conditions.

Grafting

Grafting involves attaching a scion (a young shoot or bud) from a desired kumquat variety onto a compatible rootstock. This method ensures that the propagated tree will have the same characteristics as the parent plant.

• Choose a healthy rootstock from a citrus tree with desirable characteristics, such as disease resistance or dwarfing.
• Cut a diagonal notch on the rootstock and remove a similar-sized wedge from the scion.
• Join the scion and rootstock so that the cut surfaces match up and the cambium layers (the green layer just under the bark) touch.
• Secure the graft with grafting tape or rubber bands, and seal the cut surfaces with grafting wax or a similar sealant.
• Keep the grafted tree in a protected environment until the graft has healed and starts growing.

Each propagation method has its advantages and challenges, so choose the one that best suits your experience and desired outcome.

Pests and Diseases

Kumquat trees, like other citrus trees, can be susceptible to various pests and diseases. Here’s a list of some common issues to watch for:

Citrus leafminer: The larvae of this small moth feed on young leaves, creating meandering tunnels or mines. This can cause leaf distortion and reduced tree vigor. Prune off infested leaves and use pheromone traps to reduce adult populations.

Aphids: These small, soft-bodied insects feed on plant sap, causing leaf curling and distortion. They also excrete honeydew, which can lead to sooty mold. Spray the tree with water to dislodge aphids, or use insecticidal soap or neem oil.

Scales: These small, flat insects suck sap from the plant, leading to yellowing leaves and poor growth. They also excrete honeydew, which can result in sooty mold. Scrape off scales with a brush, or use horticultural oil to smother them.

Whiteflies: They are small, white, winged insects that feed on plant sap, causing leaves to become yellow and distorted. Like aphids, they excrete honeydew, which can lead to the growth of sooty mold. To control whiteflies, use yellow sticky traps to catch adult whiteflies. Spray your kumquat tree with water to dislodge the whiteflies. Apply insecticidal soap or horticultural oil, such as neem oil, to the affected areas.

Spider mites: These tiny pests feed on plant sap, leading to the stippling and yellowing of leaves. Severe infestations can cause leaf drop and reduced tree vigor. Use water sprays to dislodge mites or apply miticides if necessary.

Citrus canker: This bacterial disease causes raised, yellow lesions on leaves, stems, and fruit. In severe cases, it can lead to defoliation and fruit drop. Prune out infected branches and apply copper-based fungicides to prevent the spread.

Citrus greening (Huanglongbing): This serious bacterial disease is spread by the Asian citrus psyllid. It causes the yellowing of leaves, small, misshapen fruit, and tree decline. There is no cure for citrus greening, so prevention and control of the psyllid vector are crucial.

Root rot: Caused by soil-borne fungi, root rot occurs in poorly drained soils and can lead to yellowing leaves, reduced growth, and tree decline. Plant kumquats in well-draining soil and avoid overwatering to prevent root rot.

To keep your kumquat tree healthy and pest-free, practice good cultural care, including proper watering, fertilization, and pruning. Monitor your tree regularly for signs of pests or diseases, and address issues promptly to prevent severe damage.

Frequently Asked Questions

What is a kumquat taste like?

Kumquats have a unique sweet and tangy flavor. The peel is sweet, while the flesh inside is tart, and they can be eaten whole, including the peel. In fact, the peel is where most of the sweetness comes from, which creates a delightful contrast with the tart flesh.

Are you supposed to eat the peel of a kumquat?

To eat a kumquat, simply wash it thoroughly and pop it into your mouth. You can eat the entire fruit, including the peel and seeds, although some people may prefer to spit out the seeds. Alternatively, you can slice the kumquat and remove the seeds before eating it.

How many kumquats can you eat?

There isn’t a specific limit to how many kumquats you can eat, but as with any fruit, it’s best to consume them in moderation. Eating a handful of kumquats as a snack or incorporating them into a salad, dessert, or another dish should be perfectly fine. However, excessive consumption of any fruit can lead to digestive discomfort or an unbalanced diet. As with all foods, it’s essential to maintain variety and balance in your diet.