Kumquat Tree Care: How to Grow Kumquats

Kumquat tree, also known as Citrus japonica, is an easy-to-grow fruit tree. From all the citrus trees, this one is the most beautiful with dark-green, glossy leaves. It’s known for its bright orange fruits, which are deliciously tart and sweet.

These trees, native to eastern Asia, are small and beautiful. If you’re looking to grow them in your backyard or near a window, then keep reading. 

Quick Care

Citrus japonica harvest
Massive harvest of kumquat fruits from a small section of one tree.
Common Name(s)Kumquat, nagami kumquat
Scientific NameCitrus japonica
Germination Time2-4 weeks
Days to Harvest~90 days for fruits to form
LightFull sun
Water:Medium
SoilSandy loam slight clay
FertilizerFrequent
PestsCitrus pests, mealybug, aphids
DiseasesArmillaria root rot, anthracnose, citrus blast

Kumquat plants have thornless branches and extremely glossy leaves. They bear dainty white flowers that occur in clusters or individually inside the leaf axils. The plants can reach a height of up to 8 feet and grow 6 feet wide. They bear yellowish-orange fruits that are oval or round in shape. The fruits can be 1″ in diameter and have a sweet, pulpy skin and slightly acidic inner pulp. 

Despite being citrus trees, the flowering season of kumquats arrives much later. Kumquat tree flowers in late spring into early summer. It is an easy-to-care, cold-hardy plant that can tolerate temperatures as low as 18°F (-7°C). 

Kumquat Varieties

Botanically, many of the varieties of kumquats are classified as their own species, rather than a cultivar:

  • Nagami: The most popular variety, also known as oval kumquat.
  • Meiwa: Large round kumquat, a hybrid of ‘Nagami’ and ‘Marumi’.
  • Marumi: Round kumquat, a bit spicier in flavor than ‘Nagami’.
  • Hong Kong: A native version, often growing in hilly or mountain regions of China.

Whichever you choose, kumquat trees produce fruit that is are round, oval-shaped, and bell-shaped. Nagami kumquats, which are the most popular, have oblong, juicy fruits, which can be eaten whole or used to make marmalades. 

All the kumquat trees are self-pollinating, so you only need to grow one tree. The plants require moist soil, so they need ample water to prevent drying of roots. Kumquats can tolerate both frigid and hot temperatures.

Planting a Kumquat Tree

Growing a kumquat tree is very easy. Here’s a breakdown of when, where, and how to plant this attractive evergreen tree. 

When to Plant

You can successfully start a new kumquat plant by planting the seed in spring. Spring is the ideal time for kumquats as the temperature is pleasant with higher chances of rain and, of course, lots of sunshine. 

Where to Plant

Plant in a place where there’s full sun. Although they’re good with any type of soil, they mainly do well in seaside conditions. You can still plant them in your backyard or outside on your patio as long as they get well-drained soil. They also do well in pots or containers with suitable drainage holes. 

How to Plant

It’s better to purchase a kumquat tree from a local nursery. Kumquat can sprout from seed, but the plant is mostly weak. Choose a sunny spot and plant the tree in spring to ensure that the kumquat is well-established before winter arrives.

After choosing the spot, dig a hole at least 3-5 times wider than the root ball. Carefully place the tree into the hall and ensure that the soil is level with the ground. Tap down the soil for a smooth layer.

Since kumquats need regular hydration, water the plant thoroughly and don’t let the soil become dry. Mist often, at least a few times a week, until the tree establishes.

Add organic mulch to the surrounding area, about 2-3 inches, while keeping the mulch at least 10 inches from the trunk.

Ensure proper watering and soil conditions for about a month and then fertilize. You can use a high-quality citrus formula.

Kumquat Tree Care

Kumquat tree flush with fruit
A kumquat tree full of fruit I harvested from this past summer.

Kumquat tree, famously known as nagami kumquat, is relatively easy to grow. However, like other citrus trees, it can’t survive on neglect. When you’re planting the tree, it’s essential to treat it with a lot of care. The journey is extremely rewarding once the kumquat tree begins to bear delicious citrus fruit. Here’s a breakdown of how to nurture and look after it. 

Sun and Temperature

As aforementioned, kumquats are best grown in full sun. They need at least 6-7 hours of sunlight every day for healthy root development. If you’re growing them indoors, make sure to keep them near a window for maximum sunlight. Kumquats do well in USDA hardy zones 9 and 10 and can survive in temperatures as low as 18 degrees F (-7 degrees C). If temperatures drop lower, bring them inside.   

Watering

The key to growing any citrus fruit tree is proper watering. If you’re growing kumquats in pots, the soil needs to be moist but not wet. For this, you must ensure the container has suitable drainage holes. 

Kumquats need regular watering, especially when the plants are young. However, make sure not to overdo it. To check for hydration, stick your finger at least 3-4 inches in the soil; if you feel dampness, wait until the soil dries out a little to water again. However, if you see a sign of dryness, water the plants until it begins to run out from the bottom of the pot. You can also light mist to avoid excess water. 

Soil

Kumquat tree survives well in almost any soil pH. But when growing it, use high-quality potting soil to enrich them. You can also add a layer of gravel or pebbles for proper drainage. 

Fertilizing

Apart from the cold winter months, kumquat plants need regular fertilizer. In spring, feed the plant with an all-purpose, slow-release citrus fertilizer. As the plant grows, give it diluted liquid fertilizer, like fish emulsion or liquid kelp, regularly. Always water before and after the application to prevent leaves from burning.  

Pruning 

Kumquat tree doesn’t require much pruning except when you have to remove dead or wilting branches that may be sucking up the tree’s resources. If you want to shape the tree, make sure to do so before the flowering season in spring and after harvesting the fruit. 

Propagating Kumquat Trees

The trees aren’t generally grown from seeds. You can propagate them by grafting them onto the rootstocks of grapefruits and oranges. 

Repotting

When growing kumquat trees in containers repot every 2-3 years in containers that are at least a few inches bigger than the previous one. The ideal time for repotting is during the leaf-growing stage in spring. 

Harvesting and Storing

Here’s how you should harvest and store the fruit from kumquat trees. 

Harvesting

The harvesting time for most varieties begins from November through January, while for others, it’s from December to April. The fruit is ripe when it’s slightly soft and deep orange. Pick the fruit using scissors to avoid damaging the plant. You can also trim the fruit along with a small piece of the branch. 

Storing

Kumquat fruits don’t have a long shelf life because they have thin, delicate peels. If you want to store them for a week or so, keep them in fully covered paper bags or plastic bags at room temperature. However, it’s best to store the fruit in the fridge. 

Troubleshooting

Even when kumquat trees require lots of care, gardeners don’t face many growing problems.

The trees are susceptible to root rot diseases if the soil isn’t well-drained. The best way to avoid this is to ensure proper drainage and only water when needed. 

Pests

Kumquat trees are susceptible to mealybug infestations, citrus pests, and aphids. Keep the soil well-drained and avoid excess moisture and piling too much mulch around the tree. A good insecticidal soap or a robust horticultural oil will help combat the infestation.  

Diseases

Root rot, citrus blast, and anthracnose are other common diseases. If you see any sign of root rot, it’s best to remove the affected branch. To prevent citrus blast, protect the trees from strong winds and follow by cutting off any diseased twigs and dead branches. 

FAQs

Q. Where do kumquats grow in the USA? 

Kumquat trees are most often grown in Florida and California. 

Q. What are the benefits of eating kumquat fruits?

Kumquat fruits are incredibly high in vitamin C and fiber. Eating them can help strengthen the immune system and support weight loss.


The Green Thumbs Behind This Article:

Kevin Espiritu
Founder

Clarisa Teodoro
Researcher

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