Kumquat Tree Care: How to Grow Kumquats

Ed Wike
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Quick Care Guide

Kumquats are a very popular small tree suitable for container growing with a small flowering tree such as ornamental grasses. The citrus tree blooms in the early spring, producing small white flowers.

Kumquat care is a breeze because the tree produces its own fertilizer and pest control. The tiny fruit it produces are yummy! They are a real treat for even the most sophisticated palettes. Since the kumquat tree is a heavy bearer, frequent fruit harvesting is necessary. A branch-bending tree, the kumquat branches come down to within 3 feet of the ground.

The kumquat fruit is eaten either fresh or used in cooking. Those with a sweet tooth really enjoy this fruit. It is sweet and sour and has a tiny, easily bite-able peel.

Kumquat care is very simple. Watering is the only real requisite. Since the tree comes from a subtropical region, it is designed to tolerate dry conditions. A once-a-week application of water is fine. If you have no in-ground sprinkling system for your container shrub, you may want to water your plants every night.

Kumquat Varieties

Kumquats are small orange fruit that look like little orange kumquats. True kumquats (Fortunella spp.) are ribbed and rounded, and they sit on branches of their parent plant, mimicking a mini fruit tree. Ross, a type of kumquat, is more round than ribbed; however, like a traditional kumquat, it grows on branches and mimics a fruit tree.

Generally, kumquat trees can stand below 8 feet but they are typically wider than they are tall. This means that kumquat fruit trees can fit on smaller patios or decks. With your kumquat tree there are many options between dwarf and standard, such as a semi-dwarf Kumquat tree. Most kumquat varieties are small, but sometimes you can find a wider variety.

Kumquat trees are generally hardy from zones 7 to 11. For safety reasons, kumquat trees are not recommended for zones 3 through 4 or 6.

Care of Kumquat Trees: Placing the kumquat tree. Once you have rescued the plant from its store house, plant your kumquat tree in the ground. Place the kumquat tree in full sun or partial shade.

Planting a Kumquat Tree

Kumquat trees can grow 6 to 12 feet tall and can be maintained at approximately 3 feet tall. The kumquat is a tropical fruit tree and requires a bit of tender care for aplenty fruit success.

The Kumquat tree is prized for its piquant fleshy fruit, with a taste reminiscent of the orange. In Florida, they are even called "sweet oranges."

Kumquats are also easy to grow. A kumquat tree can take anywhere from four to eight years to produce fruit.

Kumquats are quite hardy trees, preferring humid subtropical environments, with temperatures between 10 and 25 degrees C. Most kumquat trees remain small and are mounded in shape.

They generally come in three colors: a yellow skinned kumquat tree, a red skinned kumquat tree, and a purple skinned kumquat tree. The taste of the fruit varies depending on its color, with the red and purple being sweeter than the yellow.

The growing conditions are less flexible, however. You will want to plant your kumquat tree in a place that has full sun exposure. They also do not thrive in warm temperatures all year round. So if you live in a climate that has cool winters, you may want to plant it in a container and bring it indoors during the cold months.

Kumquat Tree Care

Kumquats are never pruned to grow into a tree. They are grown in containers.

Kumquat trees are ideal for containers because of their moderate size.

There are only two main Kumquat Tree Care tips.

{1}. Provide Kumquats with the correct amount of water and nutrients.
{2}. Keep Kumquats out of direct sunlight.

When growing kumquat tree, the health of your tree is indicated by the appearance of the leaves. If the leaves start getting brown spots, your kumquat tree is not getting enough water. If the leaves get sticky and develop a powdery mildew, it is getting too much water.

The best way to provide the right amount of water to your Kumquat Tree is to water thoroughly and deeply, then allow excess water to drain out.

In the winter, the soil should be allowed to go slightly dry between watering. In the summer, watering on a more regular schedule will be needed, usually every two to four days.

The amount of nutrients your plant gets is indicated by the condition of the leaves. If they are a deep, rich green, the tree is getting enough nutrients. If the leaves are cracked or bleached out, there may not be enough nutrients.

Sun and Temperature

Kumquat can grow happily in many areas of the sun-belt. The trees tolerate heat, dryness and salinity and can be grown as far north as New York, Pennsylvania and even Michigan.

However, kumquat trees do not tolerate freezing cold. You must keep your kumquat tree above 20 degrees Fahrenheit for it to survive a cold winter.

In the frost-free areas, kumquat is almost always grown in pots and indoors.

Kumquat trees can grow happily in the temperatures in Florida, Texas or California area.

Temperature can affect growth. It grows best if you can keep the temperature between 65 and 85 degrees Fahrenheit. If the temperature is much higher or lower, the tree may not grow properly.

Kumquat have a chilling requirement and grow best in areas with cold winters. It should be planted in the spring and outdoor grown during the summer.

Watering

The kumquat is a small, evergreen tree that grows fruit in the form of small, oval, orange fruits. There are a variety of type of kumquats, which you can then grow in many different ways. But basically, kumquats need similar types of care that other trees require.

Their soil must be well drained and it is very important that the tree be given a regular supply of water. If the kumquats are grown in containers, then it is necessary to also water the drainage layers of the plant.

The kumquat is not a particularly demanding plant and will produce much fruit when given good sunshine, fertilizer, and water. The plant growth cycle is late spring to mid-summer, so water during this time period as much as possible. It is also a good idea to water at night, rather than in the middle of the day so that the leaves of the tree do not become scorched from the hot sun.

Soil

Kumquat trees like slightly acidic, well-drained soil. Mix 2 parts clay loam, 1 part peat moss, 1 part compost, and some sand into a planting area 12-inches deep. Add a handful of bone meal for earlier fruiting. The upper 3-inches of soil mix should be loose for good water drainage.

Fertilizing

When planting kumquat trees, you want to cherish and care for the plants while avoiding the use of synthetic fertilizers. Kumquats are particularly picky about what they eat, but they'll still reward you with delicious fruit. Under good conditions, kumquat trees can grow up to 6 to 8 feet tall and provide enough fruit for you and your family to snack on and share with friends. But to enjoy the fruits of your labor, you should fertilize properly for optimum health and yield.

If it seems odd that a kumquat tree needs food, it really makes sense when you consider the fruit it bears. The kumquat fruit is a true delicacy, and it's not just because of the delicious flavors. It also features a lovely bright orange skin that the tree preserves by protecting it from disease and insects. The kumquats’ outer skin is full of beneficial antioxidants. All this healthy goodness is the result of a tree that is well-nourished. And the kumquat tree is sensitive to the type and quality of fertilizers being used. Don’t give in to the temptation to use the same type of synthetic fertilizer (with high chemical contents) that you use in your vegetable garden. Instead, follow these simple guidelines to keep a kumquat tree happy and healthy:

Pruning

In the winter, the typically evergreen Japanese Kumquat loses its leaves. Usually this coincides with cold weather, when temperatures dip in the low 30s. However, if you’re growing a Kumquat in a greenhouse, you’re going to need to prune it and other citrus trees to control growth and size.

Remove branches to avoid over-crowding. Remove branches that are at a strong downward angle, so they don’t break off. Remove any branches too long, those that are too thin, or those that are growing inward. Trim a few inches above a larger branch so that it has a diameter at least 2 to 3 times that of the smaller branches.

Prune the lower portion of the branches to an outward-facing angle of at least 45 degrees. Make sure that you do this with your hand saw to avoid nicks and cuts.

The most important aspect of pruning is the angle of the branch that you cut off. You need to make it at a 45 degree angle from the trunk of the tree, to ensure that you have the proper shape of the tree.

Cut branches at a 45 degree angle from the trunk of the tree.

Propagating Kumquat Trees

In the U.S. kumquat trees are usually grown in containers. Freestanding Kumquat trees are considered a hazard so building codes disallow the construction of supports. In addition to being a fruit tree, the kumquat is also a very decorative plant. Because the flowers contain a delicate fragrance it is a favorite among home gardeners and hobbyists.

Now for all the care you can give this delicious beverage fruit in hopes of getting your own tasty and profitable harvest.

First, though, it needs a home so you can get it off to a good start. Kumquat trees do well in containers so long as it is around 3 to 4 feet in size. Choose a pot with excellent drainage holes. The Kumquat tree is a plant for indoor/outdoor use. When the weather cools off and the nights are cold put it out of doors.

When the weather warms up put it back on the patio or deck. It is best to get it in the ground when the tree is around four to five years old. The Kumquat tree is a tropical plant and needs lots of moisture. Kumquats are very drought sensitive so it needs constant moisture.

It needs regular feeding with an indoor plant food and should never be fertilized.

It does not like to be pruned, but if you have to, do it early in the year.

Repotting

Some kumquat varieties, particularly those with many smaller fruits, should be re-potted every few years. If the rootball starts to get overgrown and rootbound, the tree will need to be re-potted into a pot a size larger.

When you repot your kumquat, you'll want to carefully loosen the rootball without breaking the plant. Try to avoid tearing or cutting the roots.

Place the tree in the new pot, and fill in the sides and the bottom of the pot with new soil. You can also amend the soil if it is lacking nutrients your tree needs.

Water thoroughly, but don't overdo it. Keep your tree in a warm, dry place for about a month to help the tree get accustomed to the new soil and pot. Once it adjusts, keep it in a more humid environment, such as a greenhouse.

Harvesting and Storing

The most typical kumquat tree fruits are 2"-3" in diameter and round or almost round in shape. They have tart but very sweet, orange-like flesh inside. The orange pulp of kumquats ripens during the cold winter months. The fruits are said to have a cinnamon taste when the peel is eaten.

There are a number of different kumquat varieties that come in a number of different sizes, and some have a more rounded shape. The best place to buy kumquat trees is at local nurseries.

Kumquats are one of the easiest, most impressive fruits to grow. In fact, if you plant kumquats in the appropriate climate, you might not do anything else to cultivate your trees. A sunny location, especially in the southern half of the country, is what you want. The soil should be well drained and slightly acidic.

The best propagation methods involve planting cuttings directly into the ground, making grafts, or pickling seeds.

Once the plants have grown to the desired height or you have transplanted the kumquat tree to a larger pot, enjoy the fruit. You can eat them or preserve them in any number of ways.

One important thing to remember about the kumquat tree is that it does not bloom in the winter. Be sure to harvest fruit before the winter months to ensure a healthy tree.

Harvesting

Trees should first be pruned several years after being transplanted. Pruning should focus on thinning out low branches to improve air circulation and sunlight penetration. This makes air circulation around the kumquat tree more efficient. It will assist the delivery of nutrients to the roots and the removal of water vapor. It will also give you clear views of developing canker and fungal diseases that need to be treated.

Be protective while thinning out branches of a kumquat tree as they are brittle and can break when bent. If the tree is to be pruned in fall or winter, be careful that branches will not damage the home or any vehicles parked outside. The best time to do pruning is during kumquat tree spring growth period because the tree is most vigorous and has the energy to fight off diseases triggered from pruning. Prune the bonsai tree kumquat in the spring to encourage strong and sturdy branching.

Do regular kumquat tree inspection and maintenance every week during the growing season. Check the plant for insects and leaf spots. Wilting leaves may indicate water shortage conditions. Inspecting the root ball for fertilizing needs is important. In case of a viral disease, one can prune out the branches and destroy them to limit the spread.

Storing

Kumquats keep well when refrigerated.

There's a downside to this, though. The flesh of the kumquat is highly sensitive to temperature fluctuations. If you stock up on kumquats to have them on hand, bring the whole batch inside and place them in the refrigerator together. If you remove a few, store them separately. It’s a good idea to keep a whole bunch in the fridge and a few others on the counter, for quick snacks.

The kumquat will last longer stored whole and unwashed. Wash them just before you eat them.

Keep in mind that kumquats are sometimes treated with wax to improve the fruit’s appearance. If you’re storing whole kumquats, you may want to remove the thin layer of wax, which can make your mouth a bit sticky.

Troubleshooting

The first sign of trouble with a kumquat tree is the leaves start to turn yellow and fall off. Next, the tree foliage begins to dry up and the plant appears to wilt. The leaves may then appear wilted even after watering. As the red color fades from the leaves, a white fungus or mildew may grow on the bark or trunk. The bark may blister or peel.

The possible causes of kumquat tree dying are fungal diseases. Unlike poor growing conditions, diseases are not reversible. This doesn’t mean the tree lives and a different choice of plant will magically solve the issue. Fungus of some type is almost always in the soil and may become active. This can happen during one of Florida’s rainy seasons.

The best way to minimize fungal diseases is to change the environment around your kumquat tree to make it more difficult for the fungus to grow and infect the tree. These changes include reducing humidity, removing dead branches, and maintaining the soil conditions.

Growing Problems

Growing kumquat plants is easy, but they do need the right conditions to thrive. Generally, these trees do not like extreme cold, frost, or snow. It is best to plant them in the winter if they are being planted in climates where they will experience frost. Instead of growing in the ground, plant them in large containers, where they will be safe.

Another thing you need to consider is that kumquats like humid environments for growth. If you are planting them in gardens, it is best to make sure that the soil is moist. In gardens, you may not have a choice but to plant the kumquats in the ground, but you have a chance of growing them even if you do plant them in the ground.

While growing kumquats, it is helpful to provide them with adequate sunlight. Like growing any plants, you need to devote enough time to providing them with ample sunlight. When growing kumquats, sunlight is essential, and allows for blue fruits to develop.

When growing these, it is important to realize that they need lots of space to grow and spread. They will need plenty of room to grow upwards, but they also need much space around them to spread out. When young, they will need to be properly spaced, so that they can grow.

Pests

Depending on where you live, kumquats get eaten by pests. Pests include the kumquat psyllid. The psyllid is a one-inch long bug that sucks the juice out of kumquats. As a result, you develop puckering, then indentations, and then where the bug sits, you might have a hole.

The adults are light brown. The hatched, immature stage are red. The nymphs have a red head and are white. If you look closely, you might see them. The nymphs have a long skinny tail, but they look a bit like some other insects.

The damage from the psyllids is not all bad news for kumquats. The good news is that psyllids are actually a sign of a healthy tree, because the tree attracts them for the sweet juice. So, if your kumquat is attacked by psyllids it's a sign that your tree is in good health.

The life cycle of the psyllids can be one to two weeks. During that time, they can deposit 100 eggs so inspect the fruit carefully.

The damage the psyllid inflicts can be avoided by harvesting the fruit when it's ripe. You could also use sticky material to trap the psyllids.

Diseases

You can use an organic spray of milk or a white vinegar to control pests on you're kumquat tree.

In addition, keep the soil a bit more acidic with 5% dolomite lime spread throughout the root zone.

Remember a lot of fertilizer and irrigation for this tree during the hot summer months.

The kumquat borer is one of the most devastating wood borers.

It strikes trees in the northern half of the United States. The female bores a hole into the tree to deposit her eggs. This causes the larvae to hatch, and instead of boring out just on the outside, they bore into the pith. The larvae will feed on the pith of the tree until they are mature and then they bore out in search of a mate. There is no way to stop the female in early stages, so your best bet is to follow the instructions above for soil. Store the trees where the temperatures are cool and dry. Remove all the fruit at the end of the growing season if you have a known problem with borers.

On the other hand, if you want to minimize your pest problems, use a two- or three-year rotation to avoid re-infestation.

Frequently Asked Questions

One of the most common issues with kumquat trees is too much sun. Kumquat trees can't take full sun. Afternoon sun is fine, but the tree can scorch and lose its leaves and fruit if left to bake in the afternoon sun.

Another common problem is not enough water. Kumquat trees need to be watered on a regular basis, and the soil should always be slightly moist. They enjoy lots of water and can tolerate moderate drought, but should never be left to dry out completely.

Because kumquat trees bloom during spring and summer, it is normal to lose flowers and even some branches during this time of the year. They will sprout back in the fall, and if branches do not sprout back after the first leaf drop, feel free to cut them away. Just remember to remove any dead branches before they fall off the tree. You should also avoid shearing the branches. This is a fine line between maintaining shape and letting the tree grow naturally.

You can prune away new growth to encourage branches to grow out sideways, but you should avoid cutting back into the tree's main limbs with your hand pruners. It is also important to prune your kumquat tree appropriately. You should never prune the tree during the summer months. They also have a tendency to bloom less the first year.