My parents have a kumquat tree in their backyard and it recently has been declining in health. Worried the tree might be dying, my parents ask me if I had any ideas. So, I did some research on kumquat trees to find out. Here’s what I found.
Kumquat trees typically die from improper watering, nutrients, or climate. However, transplant shock, pests, and disease can also affect them. For best results, water only when the soil is dry, apply compost, and plant in USDA hardiness zones 9-11. Once the source of stress is reduced, the kumquat tree should recover.
So, while kumquat trees die for several reasons, can they be saved? Let’s take a closer look.
Can Dying Kumquat Trees Be Saved?
Dying kumquat trees can be revived if you first find the proper issue and apply a timely solution. The hard part is finding out which issue is affecting them. However, a good approach is to start with the possible issues based on the symptoms and try solutions starting from the least invasive to most invasive.
The reason why we want to start with the least invasive solution first is to minimize the stress your kumquat tree gets. For example, if we’ve narrowed down the possible issues to a lack of water or drainage, it’s much easier on the kumquat to adjust its watering than it is to spray it with chemicals or dig it up.
By approaching solutions in this way, it makes it easier for you to treat your kumquat tree, as you can work your way up from simple solutions to more complex ones.
How Do You Know if Your Kumquat Tree Is Dying?
It can be difficult to tell if your kumquat tree is dying or not, but generally, if it has any of the below symptoms, it’s likely declining in health.
| Kumquat Tree Symptom | Issue* |
|---|---|
| Wilting/Curling Leaves | Under-Watered, Heat Stress, Transplant Shock |
| Yellow Leaves | Under/Over-Watered, Transplant Shock, Lack or Excess Nutrients, Pests |
| Brown Leaves | Under-Watered, Heat/Frost Stress, Transplant Shock, Pests |
| Spotted Leaves or Fruit | Pests or Diseases |
| Dropping Leaves | Under/Over-Watered, Heat/Frost Stress, Transplant Shock, Lack or Excess Nutrients, Pests or Diseases |
| Dropping Fruit | Under/Over-Watered, Heat/Frost Stress, Transplant Shock, Lack or Excess Nutrients, Lack of Pollination, Pests or Diseases |
Keep in mind that these symptoms aren’t normally a cause for concern if they’re affecting less than 10-20% of the plant. For example, it’s fairly normal for 10-20% of your kumquat tree’s leaves to be yellow or brown. The same is true for some flower or fruit drop.
However, if you’re finding that more than 20% of the tree is affected, or you’re seeing other concerning signs such as pest or disease symptoms, then action is likely needed to save the tree.
How To Save a Dying Kumquat Tree
If you’ve already tried finding out which issue your kumquat tree has, and you’ve gotten stuck, there’s still hope.
Here are 3 steps you can use to save your kumquat tree, for just about any condition.
3 Quick Steps To Save a Dying Kumquat Tree
1. Identify the Possible Issues
The first step in reviving a dying kumquat tree is to identify the possible issues. After all, the process of elimination wouldn’t work if we didn’t know which options we were eliminating!
If you haven’t seen them yet, reference the below sections for the top 5 most common kumquat tree issues.
2. Isolate the Actual Issue
Once you’ve checked the specific symptoms your kumquat tree has, you can now cross off potential issues from your list.
Try to get it down to 1-3 potential issues that best match the symptoms your kumquat tree is exhibiting. This will give you the best chances to provide the right solution for it (you don’t want to spray the tree with neem oil if the problem is a watering issue).
If you’re still not sure about the issue your kumquat tree has, that’s okay! Call up your local nursery and get their opinion on what’s happening. You may need to talk to a few people to get their experience, but there’s a strong chance they’ve seen it before and can point you in the right direction (or even provide you with the solution!).
Additionally, you can contact your local professional orchard or cooperative extension service.
3. Test Solutions
Now that you have a narrowed-down list of the potential issues, it’s time to try the solutions one at a time.
Start with the least invasive and work your way up to the most invasive. For example, providing less water is much easier than going through the process of repotting the tree. Try to save that option for last.
Continue testing the treatments you believe are most likely to fix the issue. Hopefully, one of them sticks.
Worst case scenario, start from step 1 and make a new list of possible issues. There’s a chance you might have missed something or you notice something new the second time around.
Stay persistent! It’s easy to say, “Dumb plant, why don’t you want to live?”, but there’s always a reason why plants act the way they do. Keep the course and see if you can uncover it.
Now, to give you a head start on treating your kumquat tree, let’s look at the 5 most common reasons why kumquat trees die.
The Top 5 Reasons Why Kumquat Trees Die
1. Over or Under-Watering
Over and under-watering commonly leads to a dying kumquat tree, with under-watering being the most frequent cause. Too little water and kumquat tree will curl, brown, and drop. Too much water causes root rot and dropping leaves. Only water when the soil is dry and provide 2 inches of compost and mulch.
When kumquat trees are under-watered, their leaves curl to conserve moisture. If left for too long, the leaves will begin to dry further and brown. Occasionally, this leads to leaf drop, although some kumquat trees keep their brown leaves. Under-watering is common in hot and dry climates, where soil moisture can be evaporated in a matter of hours.
On the other hand, over-watered kumquat trees often cause stagnant water in the soil and root rot. This is especially common for soils with poor drainage. Once water-logging occurs, the kumquat tree becomes stressed until the roots can have a chance to dry out a bit and fight off the root rot mold. If left with root rot, the roots decay, leading to more brown leaves before killing the tree.
While there is a lot of information out there about how to water plants, the best rule is to only water when the soil is dry. This prevents both over and under-watering as you’re only watering when the plant needs it.
Also, providing 2 inches of each compost and mulch on top of the soil goes a long way to helping the soil hold more water and increase the water independence of the tree. It also encourages deeper roots that can access deeper water. However, this should only be done once the kumquat tree has well-draining soil as these practices can make poor drainage worse.
Here’s a bit more information about compost and mulch (and why they’re so beneficial for your kumquat tree).
Compost provides valuable nutrients to the soil and increases the soil’s richness and water retention. For example, every 1% increase in the soil’s richness can hold an additional 20,000 gallons of water per acre (source).
It also feeds beneficial soil life such as earthworms and mycorrhizal fungi—which provide even more nutrients and disease resistance for the tree.
Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.
Department of Biology, University of Fribourg, Switzerland
Mulch protects the soil (and the beneficial soil life) from drying out in the sun and wind. In hot and dry weather, mulch dramatically reduces evaporation and locks in moisture from the soil. In cold weather, mulch provides a layer of insulation for the tree and its roots. Some good mulches for kumquat trees are leaves, bark, pine needles, and straw.
So, to recap:
Once you have well-draining soil, only water kumquat trees when the first 2-4 inches of soil are dry. I check for this by pushing a finger into the soil. Then, apply 2 inches of each compost and mulch under the drip line of the plant.
If you need to test your soil’s drainage, you can dig a 1-foot by 1-foot hole near the kumquat tree and fill it with water. If the hole drains slower than 2 inches per hour, it has poor drainage.
Since it can be difficult to amend garden soil due to the volume of amendments needed, providing 2 inches of compost on top of the soil is the best method. The way you avoid digging up the tree (which potentially causes transplant shock).
However, it takes time to amend the soil as the compost and mulch break down and work their way into the soil.
Also, make sure to dig the hole outside of the tree’s canopy to avoid damaging the shallow roots.
For potted kumquat trees, you can test the soil’s drainage by seeing if the water runs out of the pot’s drainage holes. If the top of the soil is staying wet for days after watering, the tree likely needs to be repotted with fresh soil.
To see which potting soils I recommend for fruit trees, check out my post: The Top 3 Potting Soils for Fruit Trees (Tested).
2. Transplant Shock
If a kumquat tree was recently planted or repotted, and it’s starting to die, it’s likely due to transplant shock. Transplant shock occurs when the plant is exposed to a new environment and has to establish a new root system. Avoid transplanting unless necessary as it can take up to 1 year for recovery.
Like many plants, kumquat trees are vulnerable to transplant shock, which can take up to a year for them to recover from. To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the tree’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the tree’s trunk and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the tree in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the trunk as before
- Apply 2 inches of compost and 4 inches of mulch to the top of the soil
- Water generously and add more soil as needed
3. Lack of Nutrients
If you’re using chemical fertilizers, provide kumquat trees with a balanced NPK (nitrogen, phosphorus, and potassium), such as a 10-10-10. Alternatively, you can apply 2 inches of compost every 1-2 months. Unlike chemical fertilizers, compost has many other benefits such as improved water retention.
Too few or too many nutrients causes yellow and brown leaves on kumquat trees. With too few nutrients, kumquat trees can’t support their leaves’ requirements, which then start to discolor and die. Too many nutrients chemically burn the plant’s roots and lead to browning and dropping leaves. Ideally, provide quality fertilizer or compost.
For more information about which fertilizers you should use on kumquat trees, check out my recommended fertilizer page. You can also make your own homemade fertilizer or compost.
Keep in mind that soil pH is equally, if not more important than nutrients. Without a proper soil pH, the kumquat tree’s roots will be unable to absorb nutrients in the soil. This also leads to discoloring and dying leaves.
Generally, kumquat trees prefer a soil pH of 6.0-7.0.
You can measure soil pH with pH strips or a pH meter. I prefer using a pH meter since they’re easy to use and affordable. To see which pH meter I use and recommend, visit my recommended tools page.
4. Climate Stress
Kumquat trees are natively from the tropics, so they prefer warm, humid environments such as USDA hardiness zones 9-11. However, this is a generalization as there are a few cold-hardy varieties that can survive in some colder zones.
Climates that are too cold or those that are hot and dry quickly pose a problem for the tropical-loving kumquat trees. In dry areas such as California, Arizona, Nevada, and parts of Texas, kumquat trees lose moisture from their leaves and soil quickly.
Much like humans, plants breathe and release moisture when hot. For plants, this is called transpiration. When the climate is too hot and dry, the transpiration and root moisture can’t effectively keep up and cool the plant and its leaves. When this happens, the kumquat tree’s leaves curl, brown, and sometimes drop.
So, the hotter and drier the weather, the more energy the tree uses to transpire and survive, and the less energy it has to use to establish its root system and grow. This drain of resources can quickly stunt or kill the tree.
For best results, keep kumquat trees in a warm and humid environment if possible. If the sun is too hot, and the tips of the leaves are browning, provide shade or move potted kumquat trees indoors. When bringing potted kumquat trees indoors, take care to avoid the hot and dry air from the central heat.
I found out about the effects of central heat the hard way. We had a surprise snowstorm last year here in Austin, Texas, and I moved my potted Meyer lemon tree inside. However, it quickly started losing its leaves. After moving it into a cooler room, it quickly started growing new leaves (see the photo below).
Also, for kumquat trees in greenhouses or indoors, many kumquat tree owners highly advocated placing 1-2 humidifiers nearby to make their kumquat trees more comfortable. Along with placing near a sunny window, these conditions help mimic the tropical environment that kumquat trees prefer.
By the way, if you live in a drier climate, and you’d like more information about the best drought-tolerant fruit trees, check out my other post: 30 Best Drought-Tolerant Fruit and Nut Trees (Ranked).
5. Pests and Diseases
Pests and diseases such as aphids, mealybug, and leaf scab can cause kumquat trees to die. Most pests can be repelled with water, oils, or sprays, while diseases can be treated with organic sprays or fungicides. Some pests and diseases such as nematodes can be deterred with companion plants like marigolds.
While not as common as the other issues on this list, pests and diseases also lead to dying kumquat trees. Generally, you can tell if your kumquat tree has a disease by inspecting the leaves for any brown or yellow spots or deformities.
You can also typically tell if pests are infecting the tree if you see them gathering on the underside of the leaves (like aphids) or holes in the tree (like borers).
If you’d like more information on the common pests and diseases that kumquat trees get, check out this resource by Epic Gardening!
A Note on Insecticides and Herbicides
We recently had an issue with caterpillars eating our basil plants and we were about FED UP. Every time we’d plant basil plants, the caterpillars ate it.
Fortunately, we found an organic spray at our local nursery that’s made from fermented rum. The day after spraying, we’d find dead caterpillars on the soil.
If you’d like to find out more about this organic spray, you can find it here on Amazon.
So, what’s my point here?
Before using chemical sprays, weigh the pros and cons and consider trying organic or permaculture-based treatments first. Even though chemical sprays and fertilizers are an easy way out, like all easy and convenient things, there are usually long-term costs!
To give you a head start, Stefan Sobkowiak – The Permaculture Orchard has a great video on a safe, homemade, and most importantly—effective fungicide (hint: the secret ingredient is whey).
